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Hassanpouryousefi, Sina. "Modeling Electrospun Fibrous Materials." VCU Scholars Compass, 2019. https://scholarscompass.vcu.edu/etd/6109.
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Electrospinning has been the focus of countless studies for the past decades for applications, including but not limited to, filtration, tissue engineering, and catalysis. Electrospinning is a one-step process for producing nano- and/or micro-fibrous materials with diameters ranging typically from 50 to 5000 nm. The simulation algorithm presented here is based on a novel mass-spring-damper (MSD) approach devised to incorporate the mechanical properties of the fibers in predicting the formation and morphology of the electrospun fibers as they travel from the needle toward the collector, and as they deposit on the substrate. This work is the first to develop a physics-based (in contrast to the previously-developed geometry-based) computational model to generate 3-D virtual geometries that realistically resemble the microstructure of an electrospun fibrous material with embedded particles, and to report on the filtration performance of the resulting composite media.
In addition, this work presents a detailed analysis on the effects of electrospinning conditions on the microstructural properties (i.e. fiber diameter, thickness, and porosity) of polystyrene and polycaprolactone fibrous materials. For instance, it was observed that porosity of a PS electrospun material increases with increasing the needle-to-collector distance, or reducing the concentration of PS solution. The computational tool developed in this work allows one to study the effects of electrospinning parameters such as voltage, needle-to-collector distance (NCD), or polymer concentration, on thickness and porosity of the resulting fibrous materials. Using our MSD formulations, a new approach is also developed to model formation and growth of dust-cakes comprised of non-overlapping non-spherical particles, for the first time. This new simulation approach can be used to study the morphology of a dust-cake and how it impacts, for instance, the filtration efficiency of a dust-loaded filter, among many other applications.
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Tsai, Chen-Chih. "Electrospun fibrous materials wetting properties /." Connect to this title online, 2009. http://etd.lib.clemson.edu/documents/1263409825/.
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Veleirinho, Maria Beatriz da Rocha. "Electrospun fibrous mats for skin and abdominal wall repair." Doctoral thesis, Universidade de Aveiro, 2012. http://hdl.handle.net/10773/9331.
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Doutoramento em QuímicaEsta tese centra-se no desenvolvimento de materiais biodegradáveis e nãodegradáveis produzidos por eletrofiação com aplicação na área biomédica. O poli(3-hidroxibutirato-co-3-hidroxivalerato) (PHBV), um poliéster biodegradável, foi selecionado como base dos materiais biodegradáveis, enquanto o poli(tereftalato de etileno) (PET), um polímero sintético, estável e biocompatível, foi selecionado para a produção das matrizes não degradáveis. Adicionou-se quitosana aos sistemas com o objetivo de melhorar o processo de eletrofiação e as propriedades morfológicas, físico-químicas e biológicas dos materiais resultantes. A composição química, bem como as características morfológicas e físicoquímicas dos materiais em estudo, foram manipuladas de modo a otimizar a sua performance como suportes celulares para engenharia de tecidos. Foram realizados estudos in vitro com cultura de fibroblastos L929 para avaliar o comportamento das células, i.e. viabilidade, adesão, proliferação e morte, quando cultivadas nas matrizes produzidas por eletrofiação. Adicionalmente foram realizados ensaios in vivo para investigar o potencial dos materiais em estudo na regeneração cutânea e como tela abdominal. Os principais resultados encontrados incluem: o desenvolvimento de novas matrizes híbridas (PHBV/quitosana) adequadas ao crescimento de fibroblastos e ao tratamento de lesões de pele; o desenvolvimento de um sistema de eletrofiação com duas seringas para a incorporação de compostos bioativos; diversas estratégias para manipulação das características morfológicas dos materiais de PHBV/quitosana e PET/quitosana produzidos por eletrofiação; uma melhoria do conhecimento das interações fibroblastos-suporte polimérico; a verificação de uma resposta inflamatória desencadeada pelos materiais nãodegradáveis quando utilizados no tratamento de defeitos da parede abdominal, o que sugere a necessidade de novos estudos para avaliar a segurança do uso de biomateriais produzidos por eletrofiação.
This thesis focuses on the development of biodegradable and non-degradable electrospun materials with application in the biomedical field. Poly(3- hydroxybutyrate-co-3-hydroxyvalerate) (PHBV), a natural biodegradable polyester, was selected as the basis of the biodegradable materials while polyethylene terephthalate (PET), a biocompatible stable synthetic polyester, was selected for the production of the non-degradable ones. Chitosan was added to both systems in order to enhance electrospinnability as well as morphological, physico-chemical, and biological features of the biomaterials. The chemical composition, morphological and some physico-chemical characteristics of these materials were manipulated toward an optimized biological performance as scaffolds for tissue engineering. In vitro cell culture studies were performed with L929 fibroblasts in order to study the cell behavior, i.e. viability, adhesion, proliferation and death, when cultured on the electrospun materials. Furthermore, in vivo assays were conducted in order to investigate the potential of the materials under study for skin and abdominal wall repair. The main achievements of this thesis include: the development of new PHBV/chitosan hybrid mats suitable for fibroblasts growth and with a good performance when used as a scaffold for skin repair; the development of a dual syringe electrospinning system for incorporation of bioactive compounds; several strategies to manipulate the morphological characteristics of electrospun materials of both PHBV/chitosan and PET/chitosan blends; an improvement of the knowledge of cell-scaffolds interactions; the detection of an important inflammatory response elicited by the non-degradable electrospun materials when used as prosthetic meshes for abdominal defect repair, suggesting the need of further studies on the safety of nanosized electrospun biomaterials.
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Zhang, Xing. "Electrospun tri-layer micro/nano-fibrous scaffold for vascular tissue engineering." Birmingham, Ala. : University of Alabama at Birmingham, 2008. https://www.mhsl.uab.edu/dt/2010r/zhang.pdf.
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Wang, Xiaokun. "Fabrication of electrospun fibrous meshes and 3D porous titanium scaffolds for tissue engineering." Diss., Georgia Institute of Technology, 2012. http://hdl.handle.net/1853/51724.
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Tissue engineering is a multidisciplinary field that is rapidly emerging as a promising approach for tissue repair and regeneration. In this approach, scaffolds which allow cells to invade the construct and guide the cells grow into specific tissue play a pivotal role. Electrospinning has gained popularity recently as a simple and versatile method to produce fibrous structures with nano- to microscale dimensions. These electrospun fibers have been extensively applied to create nanofiber scaffolds for tissue engineering applications. Specifically for bone and cartilage tissue engineering, polymeric materials have some attractive properties such as the biodegradability. Ceramic scaffolds and implant coatings, such as hydroxyapatite and silica-based bioglass have also been considered as bone graft substitutes for bone repair because of their bioactivity and, in some cases, tunable resorbability. Besides tissue engineering scaffolds, for clinical application, especially for load-bearing artificial implants, metallic materials such as titanium are the most commonly used material. Osseointegration between bone and implants is very essential for implant success. To achieve better osseointegration between bone and the implant surface, three dimensional porous structures can provide enhanced fixation with bone by allowing tissue to grow into the pores. In this study, pre-3D electrospun polymer and ceramic scaffolds with peptide conjugation and 3D titanium scaffolds with different surface morphology were fabricated to testify the osteoblast and mensechymal stem cell attachment and differentiation. The overall goal of this thesis is to determine if the peptide functionalization of polymeric scaffolds and physical parameters of ceramic and metallic scaffold can promote osteoblast maturation and mesenchymal stem cell differentiation in vitro to achieve an optimal scaffold design for greater osseointegration. The results of the studies showed with functionalization of MSC- specific peptide, polymer scaffolds behaved with higher biocompatibility and MSC affinity. For the ceramic and metallic scaffolds, microstructures and nanostructures can synergistically promote osteoblast maturation and 3D micro-environment with micro-roughness is a promising design for osteoblast maturation and MSC differentiation in vitro compared to 2D surfaces.
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Liu, Li [Verfasser], and Seema [Akademischer Betreuer] Agarwal. "Investigation of electrospun nano-fibrous polymeric actuators： Fabrication and Properties / Li Liu ; Betreuer: Seema Agarwal." Bayreuth : Universität Bayreuth, 2018. http://d-nb.info/1164077163/34.
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Kang, Jiachen, and 康家晨. "Formation and evaluation of electrospun bicomponent fibrous scaffolds for tissue engineering and drug delivery applications." Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 2010. http://hub.hku.hk/bib/B45705525.
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Vacanti, Nathaniel (Nathaniel Martin). "Investigation of electrospun fibrous scaffolds, locally delivered anti-inflammatory drugs, and neural stem cells for promoting nerve regeneration." Thesis, Massachusetts Institute of Technology, 2010. http://hdl.handle.net/1721.1/59884.
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Thesis (S.M.)--Massachusetts Institute of Technology, Dept. of Chemical Engineering, 2010.Cataloged from PDF version of thesis.
Includes bibliographical references (p. 79-82).
The organization and intricacy of the central and peripheral nervous systems pose special criteria for the selection of a suitable scaffold to aid in regeneration. The scaffold must have sufficient mechanical strength while providing an intricate network of passageways for axons, Schwann cells, oligodendrocytes, and other neuroglia to populate. If neural regeneration is to occur, these intricate passageways must not be impeded by macrophages, neutrophils, or other inflammatory cells. Therefore it is imperative that the scaffold does not illicit a severe immune response. Biodegradable electrospun fibers are an appealing material for tissue engineering scaffolds, as they strongly resemble the morphology of extracellular matrix. In this study, electrospun fibers composed of poly(L-lactic acid) (PLLA) and polycaprolactone (PCL) were prepared with and without the steroid anti-inflammatory drug, dexamethasone, encapsulated. Histological analysis of harvested subcutaneous implants demonstrated the PLLA fibers encapsulating dexamethasone (PLLA/dex fibers) evoked a much less severe immune response than any other fiber. These findings were supported by in vitro drug release data showing a controlled release of dexamethasone from the PLLA/dex fibers and a burst release from the PCL/dex fibers. The ability of the PLLA/dex fibers to evade an immune response provides a very powerful tool for fabricating tissue engineering scaffolds, especially when the stringent demands of a neural tissue engineering scaffold are considered. Structural support and contact guidance are crucial for promoting peripheral nerve regeneration. A method to fabricate peripheral nerve guide conduits with luminal, axially aligned, electrospun fibers is described and implemented in this study. The method includes the functionalization of the fibers with the axonal outgrowth promoting protein, laminin, to further enhance regeneration. The implantation of stem cells at the. site of a spinal cord or peripheral nerve lesion has been shown to promote nerve regeneration. Preliminary work to isolate and culture pluripotent, adult neural stem cells for seeding on the above mentioned scaffold is also described here.
by Nathaniel Vacanti.
S.M.
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Yeoh, Sang Ju. "Electrospun cellulose fibres from kraft pulp." Thesis, University of British Columbia, 2009. http://hdl.handle.net/2429/12930.
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Cellulose, the most abundant biomass extractable from wood, was generated in fibre form from kraft pulp by electrospinning, a fibre-producing process using electrostatic forces. Kraft pulping is the most dominant pulping technique in North America. Kraft pulp fibres (diam. 30μm) have a tensile strength of 700MPa and elastic modulus of 20GPa. In comparison, individual cellulose nanofibrils (diam. 5nm) have a tensile strength of 10GPa and elastic modulus of 150GPa. The strength displayed by cellulose nanofibrils suggests that the smaller fibre diameter could lead to a lower probability of including smaller flaw sizes in the fibre. Electrospinning has been successfully demonstrated as a one-step process to produce cellulose fibres directly from kraft pulp, thereby showing great potential for reducing cost and making the fibre-producing process more environmental friendly. Based on SEM and XRD, the electrospun fibres have a fibrillation-free, nano-filament structure with a seemingly cellulose I crystal structure, indicating significant potential for making crystalline cellulose fibres directly from kraft pulp. Contact angle measurements show that the electrospun fibres appear more hydrophobic than kraft pulp. The mechanical properties of the electrospun fibres have a large variation, suggesting the need for further process optimization. The ability to produce cellulose fibres directly from kraft pulp with improved moisture resistance and mechanical properties could potentially result in the development of more high value-added products for the Canadian pulp and paper industry, and perhaps even globally.
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Wang, Wei. "Thermo-mechanical properties of electrospun polymer fibres." Thesis, Queen Mary, University of London, 2008. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.509670.
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Kurban, Z. "Electrospun nanostructured composite fibres for hydrogen storage applications." Thesis, University College London (University of London), 2011. http://discovery.ucl.ac.uk/1333231/.
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The urgent realisation of the low carbon economy requires the development of cheap, safe and lightweight hydrogen storage, both for commercialisation of hydrogen fuel cell vehicles, and for the use of hydrogen as a reservoir of energy from intermittent renewable energy sources. The primary motivation of this PhD project was to investigate (co)electrospinning, a cheap and scalable fibre production technique, for nanostructuring potential solid state hydrogen storage materials. Solid state storage of hydrogen is being extensively investigated worldwide. However, many of the candidate materials are still not able to meet the practical requirements for mobile applications. The principal drawbacks are that these materials either have low capacity for hydrogen storage (physisorption systems), even at cryogenic temperatures, or high release temperatures with slow release rates (chemisorption systems). Because kinetic and thermodynamic properties can be improved by nanoscale processing, nanoengineering of selected materials has emerged as one of the most effective ways of overcoming their associated performance barriers. In this thesis I present two successful approaches to nanostructuring using electrospinning: firstly, by encapsulating chemical hydrides in polymeric nanofibres, as demonstrated by the development of co-axial ammonia borane-encapsulated polystyrene (AB-PS) fibres, and secondly, by post-processing of single-phase electrospun PAN fibres, resulting in the synthesis of potassium-intercalated graphitic nanofibres (K-GNFs). The results show that the micro and nano-structure imparted through electrospinning, can have the effect of reducing dehydrogenation temperatures in AB-PS fibres (from 110 to ~85 °C) and improving the (de)hydrogenation rates by an order of magnitude in both composite fibres (from ~50 to <5 mins in K-GNFs and from ~150 minutes to as low as 15 minutes in AB-PS fibres). The details of co-axial electrospinning as a novel approach to nanoengineering chemical hydrogen storage materials and as a way of possibly overcoming issues regarding reversibility, stability and clean hydrogen release from many of these materials is discussed. The solution selection method I have developed for use in the synthesis of co-axial composite fibres can be applied as an efficient solution selection formula for multi-phase electrospinning in general.
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Aladdad, Afnan. "Dynamic patterned electrospun fibres for 3D cell culture." Thesis, University of Nottingham, 2016. http://eprints.nottingham.ac.uk/33895/.
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Current culture methods to generate large quantities of cells destined for tissue engineering and regenerative medicine commonly use enzymatic digestion. However, this method is not desirable for subsequent cell transfer to the body due to the destruction of important cell-surface proteins and the risk of enzymatic contamination [1]. Therefore, research has led to the development of thermo-responsive surfaces for the continued culture of mammalian cells, with passaging achieved via a drop in the culture temperature. Recognising that the three-dimensional (3D) culture environment influences the cell phenotype, our aim was to generate a thermo-responsive 3D fibre-based scaffold, using electrospinning, to create an enzyme-free 3D culture surface for mammalian cell expansion that would be suitable for cells destined for the clinic. Thermo-responsive poly (poly (ethylene glycol) methacrylate), poly (PEGMA188), with lower critical solution temperature (LCST) of 26°C has been proposed for use within this thesis. It was used in combination with poly (lactic-co-glycolic acid) (PLGA) and poly (ethylene terephthalate) (PET) polymers in order to create 3D thermo-responsive non-woven electrospun fibrous scaffolds, on which different cell types could be cultured and passaged. Poly (PEGMA188) was prepared by free radical polymerization, and then incorporated with PLGA and PET polymers via four different methods: (i) surface adsorption, (ii) NaOH surface treatment, (iii) surface entrapment and (iv) blend-electrospinning. Blend-electrospinning was chosen over the other methods as it produced nano-PET and micro-PLGA bead-less fibres with responsive behaviour. The biocompatibility was assessed via the adhesion and proliferation of different mammalian cell types, including (i) red fluorescent protein (RFP)-expressing 3T3 fibroblasts, (ii) green fluorescent protein (GFP)-expressing primary immortalized human mesenchymal stem cells (ihMSCs), (iii) human colon adenocarcinoma cells (Caco2) and (iv) primary human corneal stromal stem cells (hCSSCs). The cell viability (Alamar Blue assay) was determined to measure the difference in cell populations adherent to the scaffolds while changing the culture temperature. These thermo-responsive scaffolds were able to support cell adhesion and proliferation at 37°C (hydrophobic surface). Furthermore, it was possible to detach the cells from the scaffolds by decreasing the temperature to 17°C (hydrophilic surface). Irrespective of the concentration of poly (PEGMA188) used, all scaffolds exhibited thermo-responsive proprieties; the cells were viable and proliferated in a similar manner to those cultured on control surfaces (PLGA or PET scaffolds). Finally, the effects of the thermo-responsive polymer and 3D culture environment on the hCSSC phenotype were assessed by quantitative reverse transcription-polymerase chain reaction (RT-qPCR) and immunocytochemistry. The application of 3D environments can promote the reversion of activated corneal stromal cells’ ‘fibroblastic phenotype’ to a desirable quiescent keratocyte phenotype. Therefore, seven thermal and enzymatic passages on responsive 3D scaffolds and 2D TCPS, respectively, were performed. Cell culture on the 3D scaffolds promoted the quiescent keratocyte phenotype, with the increased expression of the keratocyte markers, CD34 and ALDH, and decreased expression of the myofibroblast marker, ACTA2, when compared with cells cultured on the 2D culture flasks. In this thesis, the preparation and application of first generation, biocompatible thermo-responsive fibrous scaffolds are described. The combination of ease of preparation, positive cell response and the expansion of a desirable cell phenotype make the thermo-responsive fibres promising as a new class of materials for application in cell culture. The materials developed and studied in this thesis are believed to represent a significant contribution to the fields of biomaterials and tissue engineering.
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Katsogiannis, Konstantinos A. G. "Single step production of nanoporous electrospun poly(ε-caprolactone) fibres." Thesis, Loughborough University, 2016. https://dspace.lboro.ac.uk/2134/22929.
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Nanoporous polymer fibres are currently attracting increasing interest due to their unique characteristics. Increased specific surface area, improved mechanical properties and improved cellular growth are amongst the advantages that set porous fibres as ideal candidates in applications like catalysis, separation and tissue engineering. This work explores the single step production of porous poly(ε-caprolactone) (PCL) fibres through combinative electrospinning and Non-solvent Induced Phase Separation (NIPS) technique. Theoretical models, based on three different contact models (Hertzian, DMT, JKR), correlating the fibrous network specific surface area to material properties (density, surface tension, Young s modulus, Poisson s ratio) and network physical properties (density) and geometrical characteristics (fibre radius, fibre aspect ratio, network thickness) were developed in order to calculate the surface area increase caused by pore induction. Experimental results proved that a specific surface area increase of up to 56% could be achieved, compared to networks composed of smooth surfaced fibres. The good solvent effect on electrospun fibre surface morphology and size was examined through experimental investigation of four different good solvent (chloroform, dichloromethane, tetrahydrofuran and formic acid) based solutions at various good/poor solvent ratios. Chloroform was proven to be the most suitable solvent for good /poor solvent ratios varying from 75-90% v/v, whereas alternative mechanisms leading to different fibre morphologies were identified, interpreted and discussed. Evaporation rate of the good solvent was identified as the key parameter of the process. Second order polynomial equations, derived from the experimental data, correlating the feed solution physical parameters (viscosity, conductivity, surface tension) to the fibre average diameter produced were developed and validated. Response surface methodology was implemented for the design and conduction of electrospinning experiments on a 12.5 % w/v Chloroform/DMSO solution 90/10 % v/v in order to determine the individual process parameters (spinning distance, applied voltage, solution flow rate) effect in fibre surface morphology and size. The increase in any of these parameters results in increase of both the fibre size and the tendency for pore generation, whereas applied voltage was the parameter with the strongest effect. Findings from this thesis expand the knowledge about both phenomena occurring during the production process and end product properties, and can be used for the production of controlled morphology and size porous poly(ε-caprolactone) (PCL) fibres.
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Tung, Wing-tai, and 董永泰. "Preparation of electrospun chitosan fibres for Schwann cell-guided axonal growth." Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 2014. http://hdl.handle.net/10722/208170.
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Schwann cell-seeded guidance channels have been exploited to bridge and guide axonal re-growth across gaps in lesioned nerves. Mis-orientation of Schwann cells in the channels can however distort axonal growth within the lesion. We therefore propose to orient the growth of Schwann cells on aligned nanofibers such that axonal growth can be guided along the designated direction towards the target. Chitosan was the choice scaffold material given its biocompatibility and the tunable susceptibility to biodegradation. To be suitable for electrospinning, chitosan was dissolved in trifluoroacetic acid/methylene chloride solution. By replacing the grounded plate collector of the conventional electrospinning setup with parallel collector plates placed 1.6 cm apart, the positively charged chitosan fibersbecame alternately attracted to the parallel plates and ended up uniaxially aligned as fiber suspension across the plates. Stability of the chitosan fibers in aqueous, physiological environment was achieved with the use of sodium carbonate to neutralize residual acidity in the chitosan fiber preparation. Schwann cells seeded onto these stabilized aligned chitosan nanofibers aligned uniaxially with the chitosan nanofibers. In addition, by seeding dissociated cells of dorsal root ganglia (DRG, E14/15 rats) onto the uniaxially aligned nanofibers, both neurons and Schwann cells were aligned with uniaxial arrangement of nanofibers, and the Schwann cells showed myelination ofthe axons. A model of the chitosan nerve conduit was constructed with a core nanofiberbundle, and seeding of Schwann cells. Thesein vitro results provide proof-of-principle for pursuing improvement in post-traumatic recovery from nerve injury with use of uniaxially aligned chitosan nanofibers in Schwann cell-seeded nerve guidance channels.published_or_final_version
Biochemistry
Master
Master of Philosophy
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Akanbi, Muftau Jide. "Design and engineering of electrospun fibres for oil spill clean-up." Thesis, University College London (University of London), 2018. http://discovery.ucl.ac.uk/10052906/.
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The superior oil sorption performance of electrospun polystyrene (PS)/PS-based fibres has rendered its use more competitive than the commercial melt blown polypropylene (PP) fibres. However, on a microscale level, the oil - sorbent interaction and its effect on the sorption behaviour is yet to be fully understood; considering PP polymer is known to have a lower surface energy than polystyrene. Furthermore, the commercialisation of electrospun PS sorbent has been hindered due to the poor mechanical strength of the fibre mats particularly after oil sorption. Therefore, the aim of this thesis is to (1) enhance the understanding of the oil sorption behaviour of electrospun PS fibres (single filament level) and (2) to explore ways to effectively enhance the mechanical properties of the PS fibre mat. The oil adherence potential of filaments of electrospun PS and subsequent comparison with filaments of the commercial melt blown PP sorbent was quantitatively evaluated using drop-on-fibre micro-sorption technique. This was preceded by a systematic optimisation of the electrospinning process, 20%w/w concentration of PS dissolved in DMF/THF (4:1) gave fibres with the best morphology for the micro-sorption test. Further experiments showed single filaments of electrospun PS to exhibit the strongest affinity to the two oils tested, with a mean adhesive energy of 18.0 x 10-13J and 26.2 x 10-13J for sunflower and motor oil respectively. This represents values 3 – 6 times higher than those recorded for single filaments of the PP counterparts. The superior oil adsorptivity of PS fibre was attributed to its chemical structure i.e. the presence of aromatic phenyl group in its structure. For the second aim of this thesis, a single step electrospinning method of blending PS and thermoplastic polyurethane PU polymers in different weight ratio of PSPU polymer blend was explored, using either a Flat Collector (FC) or a Drum Collector (DC) system. This was done in order to enhance the mechanical properties of PS fibres. The method is a simple, cost-effective engineering approach and exhibits great potential. The ultimate tensile strength (UTS) and elongation at UTS were seen to rise with increased PU content. Samples of PSPU ratio 6:4 fabricated using a DC system (PSPU_DC 6:4) and those fabricated using the FC system (PSPU_FC 6:4) recorded a 600% and 1000% increase in tensile strength respectively, in comparison to the pure PS mat. The oil sorption and retention capacities was seen to be dependent on several variables including the fibre collection system. Post treatment of the fibre mat using heat treatment around the polymer glass transition temperature (110oC) was seen to induce inter-fibre bonds, with the amount of bonds seen to rise with increase in treatment temperature. This causes a simultaneous increase in tensile strength. The work presented in this thesis has pioneered some key aspects that will take electrospinning of polymer fibres further. In terms of characterization, it is the first to quantitatively evaluate the oil adsorptivity of filaments of electrospun PS and melt blown polypropylene sorbents. This creates fundamental insight into the sorption mechanism at a micro-scale level to aid the design of future and improved electrospun sorbents. Also, the electrospinning of PS and PU presented in this thesis, is the first time polymer blend of both polymers is being electrospun for any application, with detailed characterisation of the bi-component fibres presented.
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Fischer, Sara Nicole. "Electrospun Nanofiber Scaffolds as a Model of the Lung Microenvironment in Pulmonary Fibrosis." The Ohio State University, 2011. http://rave.ohiolink.edu/etdc/view?acc_num=osu1313117096.
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Fotticchia, Andrea. "Design and development of anisotropic laminate scaffolds of electrospun polycaprolactone for annulus fibrosus tissue engineering applications." Thesis, Loughborough University, 2016. https://dspace.lboro.ac.uk/2134/21407.
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In several cases, current therapies available to treat a large number of musculoskeletal system diseases are unsatisfactory as they provide only temporary or partial restoration of the damaged or degenerated site. In an attempt to maintain a high standard of life quality and minimise the economic losses due to the treatments of these frequently occurring ailments and subsequent lost working days, alternative therapies are being explored. Contrary to the current treatments, tissue engineering aims to regenerate the impaired tissue rather than repair and alleviate the symptoms; thus offering a definitive solution. The annulus fibrosus (AF) of the intervertebral disc (IVD) is a musculoskeletal system component frequently subjected to degeneration and rupture, characterised by predominance of anisotropically arranged collagen fibres. In the present thesis, electrospinning technology is used to fabricate polycaprolactone (PCL) scaffolds intended to replicate the anisotropic structure of the AF.
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Mohan, Saeed. "A small angle neutron scattering study of polymer chain trajectories in electrospun fibres." Thesis, University of Reading, 2011. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.577778.
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The electrospinning technique transforms a polymer solution of sufficient concentration from a sub-millimetre sized droplet to a fibre ranging in diameter from tens of micrometers to tens of nanometres by application of a sufficiently strong electric field. A polymer jet is extruded from the droplet and a solid fibre is deposited onto a grounded collector. During this transition a large scale transformation occurs and the solvent is rapidly removed from the polymer jet. The purpose in this investigation is to develop a model of how the polymer chain conformation is altered from the solution state to that of the fibre by the electrospinning process using the technique of small angle neutron scattering (SANS). Using SANS in conjunction with isotopically labelled samples the polymer chain conformation in high dielectric constant solvents was measured at the high concentrations, associated with electrospinning. It was determined that for the concentrations used in electrospinning in this work, the solutions were all in the semi-dilute state, meaning that the polymer chain was in a swollen conformation and its dimensions were greater than those in the bulk state. The chain conformation in the polymer fibres was also measured with the aid of SANS and was determined to exhibit chain dimensions comparable to that measured in the solution. The level of extension inherent to the electrospinning process was measured by collection of aligned fibres. It was determined that the chains extend ~5% parallel to the fibre axis. A relatively small extension compared to the large macroscopic transformation of the fibre. The level of extension was further increased to ~20% through mechanical deformation by use of a rotating collector. The polymers relaxation rate, the solvent evaporation rate and any formation of a polymer skin play a significant role in determining the level of molecular anisotropy in the fibres.
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Meltz, Freda-Jean. "Amphiphilic electrospun fibres of poly(methacrylic acid)-graft-poly(dimethylsiloxane) copolymers as a means to controlling electrospun fibre morphology and obtaining nanofibre hydrogels." Thesis, Stellenbosch : Stellenbosch University, 2014. http://hdl.handle.net/10019.1/86620.
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Thesis (MSc)--Stellenbosch University, 2014.ENGLISH ABSTRACT: Novel poly(methacrylic acid)-graft-poly(dimethylsiloxane) copolymers were synthesised by conventional free radical reactions using a poly(dimethylsiloxane) macromonomer. The polymers were electrospun to investigate how the fibre morphology can be modified by manipulating the electrospinning solution parameters, and to determine the possibility of using the polymers as new materials for the production of polymer nanofibre hydrogels. The electrospinning solution parameters were varied by electrospinning the highly amphiphilic copolymers in solvents with variable solvent qualities. Scanning Electron Microscopy (SEM) and Field Emission Scanning Electron Microscopy (FE–SEM) was used to investigate the fibre morphology. Internal morphology was studied using a freeze fracture technique prior to FE-SEM imaging. It is revealed that the polymers in this study does not form any fine structure or pores even when self-assembled structures are present in the solution. Attempts were made to visualise any self-assembled structures of films produced from dilute solutions using TEM. Further studies included investigating the fibres properties, primarily with regards to their rate and extent of moisture and water uptake. The fibres showed hydrogel behaviour and the PDMS content were found to have an impact on the hydrogel stability. Post electrospinning crosslinking of the nanofibres was also explored.
AFRIKAANSE OPSOMMING: Unieke ent-kopolimere wat bestaan uit poli(metielakrielsuur) (PMAS) en poli(dimetielsiloksaan) (PDMS) is gesintetiseer deur middel van 'n “ent-deur” vryeradikaalkopolimerisasie. 'n PDMS makromonomeer is vir hierdie doel gebruik. Die polimere is geëlektrospin om vesels te vorm. Die doel was om die invloed van verkillende strukture in oplossing op die veselmorfologie te bepaal. Die moontlikheid om hierdie nanovesels as gels te gebruik is ook ondersoek. Die amfifiliese kopolimere is geëlektrospin uit die oplossing waarin dit wisselende oplosbaarheid toon. Skandeer elektron mikroskopie (SEM) is gebruik om die morfologie te ondersoek. Die interne morfologie van die vesels is ondersoek deur die vesels te vries en in die gevriesde toestand te breek. Die studie het getoon dat geen strukture op, of binne, die vesels vorm nie, selfs al moes daar assosiasie tussen segmente van die polimere gewees het. Hierdie tipe assosiasies sou strukture in die oplossing tot gevolg gehad het. 'n Poging is aangewend om die strukture in oplossing te visualiseer deur transmissie elektron mikroskopie (TEM) van dun films te ondersoek. Films is vanaf verdunde oplossings gevorm. Ander studies het ingesluit om die eienskappe van die vesels te ondersoek, met die fokus op hoeveel en hoe vinnig die vesels waterdamp en water kon absorbeer. Die vesels het soos 'n gel reageer. Hierdie gedrag is beïnvloed deur die hoeveelheid PDMS wat 'n definitiewe invloed op die stabiliteit van die gel gehad het. Kruisverbindings van die vesels, nadat dit geëlektrospin is, is ook ondersoek.
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Zhang, Xi. "Polymer composites incorporating engineered electrospun fibres : flexible design and novel properties for biomedical applications." Thesis, Queen Mary, University of London, 2017. http://qmro.qmul.ac.uk/xmlui/handle/123456789/30904.
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Due to their unique structure and flexible choice of materials, electrospun degradable and biocompatible polymer fibres are considered to be extremely suitable for biomedical applications such as tissue engineering and drug delivery, either on their own or integrated within composites. Conventional electrospun fibre composites are typically based on non-woven mats and therefore limited to simple-curved geometries (films, membranes, etc.). For aqueous composites such as hydrogels, the hydrophobicity of the materials sometimes prohibits fibres to be easily integrated or distributed in these composites. In this thesis, a review on the topic is firstly presented in Chapter 2, introducing and discussing engineering of electrospun fibre as well as their biomedical applications. In Chapter 3, electrospun polylactide (PLA) fibres reinforced poly(trimethylene carbonate) (PTMC) composites are prepared. The composites are loaded with both continuous and short PLA fibres, achieving significant mechanical enhancement and offering opportunities to produce composites conveniently using liquid formulations. Chapter 4 presents the development of shape memory polymer composites based on a combination of PLA fibres and a PTMC matrix. By loading different amounts of short fibres with different aspect ratios or by using plasticisers, the shape memory behaviour is modulated; and composites of more complex geometries are produced. In Chapter 5, PTMC-PLA fibre composites are made into drug release system. Dexamethasone-loaded PLA fibres are integrated into a PTMC matrix, showing sustained drug release and stimulating stem cell osteogenic differentiation. This concept gives promise to loading various drugs into photo-crosslinked structures without denaturation. In Chapter 6, electrospun PLA fibres are functionalized by amphiphilic block copolymer polylactide-block-poly[2-(dimethylamino)ethyl methacrylate] (PLA-b-PDMAEMA) for the development of carboxymethylcellulose composites hydrogels. Functionalization of PLA fibres not only allows for easy integration and dispersion into the hydrogel, but also enhances the interfacial bonding between fibre and hydrogel. In the last chapter (Chapter 7), some conclusions are drawn and future works are discussed.
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Sun, Wenjun. "Fabrication and characterization of electrospun alumina nanofibre reinforced polycarbonate composites." Thesis, Queen Mary, University of London, 2017. http://qmro.qmul.ac.uk/xmlui/handle/123456789/25980.
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Fibres with ultra-high tensile strength have attracted unprecedented attention due to the rapidly increasing demand for strong fibre reinforced composites in various fields. However, despite a theoretical strength as high as around 46 GPa, current commercial alumina fibres only reach strength value of around 3.3 GPa because of the defects between the grains. Electrospinning provides a method to produce ceramic nanofibres with diameters reduced to nano-scale with effectively enhanced strength. Different calcination procedures were applied to study the morphology and crystal structure growth of alumina. Tested with a custom-built AFM-SEM system, the tensile strength of single crystal α-alumina nanofibres were found to have little dependence on diameter variations, with an average value of 11.4±1.1 GPa. While the strength of polycrystalline γ-alumina nanofibres were controlled by defects, showing a diameter dependent mechanism. Apart from the intrinsic properties of the fibre and matrix, the interface between them also plays an important role in determining composite mechanical properties. Collected by a rotating drum during electrospinning, aligned fibres were used to reinforce polycarbonate matrix for fabricating composite. The composite mechanical properties were successfully improved after surface modification with silane coupling agent. With a fibre volume fraction of around 7.5%, the composite strength doubled and the Young's modulus increased by a factor of 4 when compared with the pure polycarbonate. Apart from surface modification, the fibre/matrix interface can also be affected by transcrystallinity. Transcrystalline layers were formed in the alumina reinforced polycarbonate composites after annealing. Significant enhancement of the Young's modulus of the crystallized polycarbonate by a factor of 3 compared to the amorphous phase was measured directly using AFM based nanoindentation. Optimization of the Young's modulus is suggested as a balance between extending the annealing time to grow the transcrystalline layer and reducing the processing time to suppress void development in the PC matrix.
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Natesan, Pooja Vardhini. "Fabrication and characterization of polycaprolactone/graphene oxide electrospun scaffolds for tissue engineering applications." Master's thesis, Universidade de Aveiro, 2016. http://hdl.handle.net/10773/17129.
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Mestrado em Engenharia MecânicaA recente evolução científica no campo da engenharia de tecidos (TE) criou oportunidades únicas para fabricar tecidos de substituição de órgãos artificiais em laboratório a partir de combinações de matrizes extracelulares (andaimes), células e moléculas biologicamente ativas. adicionalmente, a formulação de compósitos poliméricos reforçados com cargas nanométricas como o óxido de grafeno (GO) mostrou ser possível uma grande melhoria de várias propriedades destes compósitos em relação aos polímeros simples. No presente estudo, matrizes fibrosas de policaprolactona (PCL) e de PCL-GO foram preparadas através de eletrofiação sob diferentes condições. Foi analisado o efeito de vários parâmetros de electrofiação tais como, peso molecular do polímero, solventes, concentração, caudal, tensão e distância de trabalho, sobre a morfologia das fibras eletrofiado. A incorporação de GO nas fibras de PCL alterou a morfologia, química de superfície e as propriedades mecânicas das fibras de PCL compósitos, o que foi comprovado por meio de várias técnicas de caracterização. As matrizes fibrosas de PCL-GO com a concentração de GO de 0,1% em peso demonstraram ser a combinação mais interessante para estudos futuros em TE.
Scientific advancements in the field of tissue engineering (TE) have created unique opportunities to fabricate artificial tissue or organ replacement components in the laboratory from combinations of engineered extracellular matrices (scaffolds), cells and biologically active molecules. Polymer composites reinforced with nanosized graphene oxide (GO) fillers have shown large improvement of various properties over the pristine polymers. In the present study, polycaprolactone (PCL) and PCL-GO fibres were prepared through electrospinning under different conditions. The effect of several electrospinning parameters (polymer molecular weight, solvent system, concentration, flow rate, voltage and working distance) on the morphology of the electrospun fibres was investigated. The GO nanosheets were successfully incorporated into the PCL fibres and the changes in the morphology, surface chemistry and mechanical properties were analyzed through various characterization techniques. The PCL-GO electrospun fibres with GO concentration of 0.1 wt% was found to be the most attractive combination which can be utilized for future TE applications.
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Li, Qiang. "Growth of carbon nanotubes on electrospun cellulose fibres for high performance supercapacitors and carbon fibre composites." Thesis, University of Exeter, 2018. http://hdl.handle.net/10871/34360.
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The production of cellulose derived hybrid carbon nanofibre (CNF)/carbon nanotubes (CNTs) electrodes for the fabrication of supercapacitors and carbon fibre composites was investigated. The CNTs were grown via a floating catalyst chemical vapor deposition (CVD) method on the top surface of electrospun cellulose derived CNFs. These CNF and CNF/CNTs samples were then used as electrodes to produce liquid electrolyte-based supercapacitors. The growth of CNTs leads to an improvement of electrochemical performance compared to the plain CNFs. This improvement is due to the grown CNTs enlarging the reactive sites through enhanced surface area and porosity, and thereby increasing the conductivity of the system. CNTs have been also grown onto CNFs containing ferrocene and SiC particles. Composites were fabricated by combining the fibres and CNTs grown fibres with model polymers. The stress transfer properties of these materials have been estimated using an in situ Raman spectroscopic method by observing the shift of the Raman band during the tensile deformation of model polymer composites. Using this method, the elastic modulus of CNF/SiC/CNTs fibres has been estimated to be 208 ± 26 GPa. No shifts in the peak positions of bands relating to the carbon structure were obtained for in situ Raman spectroscopic studies of the CNF/CNTs fibres made from the ferrocene embedded fibres. This was thought to be due to the low yield of CNTs on the surface of the fibres. Furthermore, CNF/CNTs electrode-based structural supercapacitors, combining a solid electrolyte with the carbonized fibres, have been produced. These CNF/CNTs electrodes have a better capacitive performance than the plain CNF electrodes. There was a decrease in this performance with increased curing time of the resin, from 2 to 24 h, due to a lack of charge carrier mobility in the latter samples. A Raman spectroscopic study of the deformation of the carbon structures showed that the G-band shift towards a lower wavenumber position for the CNF and CNF/CNTs samples processed at a carbonization temperature of 2000 °C. Moduli of these fibres were estimated to be ~145 GPa and ~271 GPa, respectively, suggesting the growth of CNTs not only enhances the capacitive performance but also the mechanical properties of the structural supercapacitors. No Raman bend shift was found for the CNFs and CNF/CNTs samples processed below a carbonization temperature of 2000 °C, e.g. 900 °C and 1500 °C. This is because the graphitic structures are not well developed at carbonization temperatures below 1500 °C.
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Enz, Eva [Verfasser], J. P. F. [Akademischer Betreuer] Lagerwall, M. [Akademischer Betreuer] Steinhart, and A. [Akademischer Betreuer] Blume. "Electrospun polymer : liquid crystal composite fibres / Eva Enz. Betreuer: J. P. F. Lagerwall ; M. Steinhart ; A. Blume." Halle, Saale : Universitäts- und Landesbibliothek Sachsen-Anhalt, 2013. http://d-nb.info/1033789976/34.
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Belanger, Kayla Ann. "A functionalizable nerve graft design based on an organized electrospun silk fibroin nanofiber biomaterial for peripheral nerve regeneration." Thesis, Compiègne, 2017. http://www.theses.fr/2017COMP2410/document.
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Une lésion au niveau d’un nerf périphérique peut provoquer la perte de fonction sensorielle et motrice, et dans le cas de neurotmésis, la régénération spontanée ne se produira pas. De plus, si l’espace entre les deux segments de nerf est trop important, une suture directe n’est pas possible et l’implantation d’une greffe est nécessaire afin de créer une liaison entre les deux segments de nerf. L’autogreffe de nerf est le « gold standard » pour des procédés de réparation nerveuse : une portion d’un nerf sein (qui est considéré comme un nerf moins important) est prise du même patient et implantée au site de la lésion. Cependant, il existe plusieurs désavantages avec ce procédé comme une deuxième chirurgie, la perte de fonction au site du don, la possibilité de développer un neurome sur ce même site, ainsi qu’un taux de réussite de 50% dans les cas où l’espace entre les deux segments de nerf est très important. Il reste donc, un besoin de trouver un procédé alternatif afin d’augmenter le taux de réussite et d’éliminer les désavantages de l’autogreffe. L’objectif de cette étude est d’avancer vers une solution alternative de l’autogreffon en utilisant des biomatériaux. Cette thèse se divise en trois parties. La première se focalise sur le développement d’un modèle de guide nerveux basé sur des nanofibres de fibroïne de soie. Ce matériau est composé d’une organisation complexe qui inclut deux surfaces de nanofibres alignées avec une couche de nanofibres aléatoires à l’intérieur afin d’améliorer des propriétés mécaniques du matériau sans la perte d’orientation des fibres pour la régénération nerveuse. Le matériau est ensuite manipulé pour fabriquer un tube, multi-canaux avec une « enveloppe » supplémentaire afin de faciliter le procédé d’implantation chirurgicale. Ce guide nerveux a été soumis pour l’obtention d’un brevet européen le 12 juillet 2017 et cela est le sujet d’un deuxième article qui a été soumis pour publication. La deuxième partie de cette étude explore des possibilités d’une fonctionnalisation du matériau afin d’améliorer son efficacité pour la régénération nerveuse. Cette étude explore la fonctionnalisation de la fibroïne de soie avec une deuxième protéine, plusieurs facteurs de croissance, et des nanoparticules. Chacune de ces fonctionnalisations donne une possibilité d’ajouter des propriétés favorables à la fibroïne de soie, un matériau naturel et biocompatible. La troisième partie de cette étude examine l’efficacité d’un guide nerveux composé de la fibroïne de soie fonctionnalisée avec des facteurs de croissance pour la régénération nerveuse périphérique en comparaison avec un guide nerveux composé de la fibroïne de soie sans aucune fonctionnalisation et une suture direct (qui simule une autogreffe). Trois techniques d’évaluation différentes de la régénération nerveuse ont été réalisées afin d’obtenir une analyse plus complète. Il y a de nombreux mécanismes impliqués dans la régénération nerveuse, il est donc nécessaire d’étudier différents paramètres pour analyser l’efficacité de régénération. Les résultats d’analyses histologiques, d’électromyographie, et de capture de mouvement, ont été considérées ensemble afin d’arriver à une conclusion sur la réussite d’une régénération nerveuse pendant cette étude. Pour conclure cette étude, les guides nerveux fonctionnalisés avec une combinaison de facteurs de croissance démontrent une meilleure régénération nerveuse et une récupération de fonction supérieureInjury to a peripheral nerve can cause loss of sensory and motor function, and if the injury is very severe where the nerve undergoes neurotmesis, unassisted nerve regeneration may not occur. In this case, where the gap between nerve segments is too large to carry out a direct end to end suture, a graft is sutured to bridge the gap between sectioned nerve segments. The autologous nerve graft, where a portion of a less important nerve from the same patient is removed and grafted between nerve segments, continues to be the gold standard procedure for nerve repair. However, there are several drawbacks of this technique including a second surgical procedure, loss of function at the donor site, possibility of developing a painful neuroma at the donor site, and the 50% success rate of autografts used in large gaps. There is therefore a need for a tissue engineered nerve graft that can replace the autograft, and this study aims to advance toward an effective autograft alternative. This PhD is presented as a three part study consisting first of the development of a novel nerve guidance conduit based on a tri-layered silk fibroin nanofiber material comprised of a complex organization including two aligned fiber surfaces and a randomly deposited fiber interior to improve the mechanical properties of the material while not compromising the guidance capabilities of aligned nanofibers for nerve regeneration. The material is then used to fabricate a multi-channeled tube with an additional “jacket layer” in order to facilitate surgical implantation. This NGC has been submitted to be patented on July 12, 2017 and is the subject of the second article submitted for review for publication. The second part of this study explores the different possibilities of the functionalization of the material in order to improve the effectiveness for nerve regeneration. This study explores functionalizing the silk fibroin with a second protein, several growth factors, and nanoparticles that all have potential to add favorable properties to the natural biocompatible silk fibroin material. The final part of this study tests the effectiveness of growth factor-embedded silk fibroin NGCs for peripheral nerve regeneration in comparison with non-functionalized silk fibroin devices and a direct suture to simulate results obtained with an autograft. Three different techniques for the evaluation of nerve regeneration were used in order to produce a more comprehensive analysis. As there are many mechanisms involved in nerve regeneration, only one or two analysis techniques cannot paint a complete picture of the success of nerve regeneration. Therefore, histological analyses, electromyography analyses, and motion capture analyses were carried out and considered together in order to make a conclusion on the level of nerve regeneration success during this study. The conclusions from this study were that a NGC functionalized with a combination of growth factors appeared to exhibit the most successful nerve regeneration and functional recovery
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Bayley, Gareth Michael. "Novel electrospun fibres of amphiphilic organic-inorganic graft copolymers of poly(acrylonitrile)-graftpoly( dimethylsiloxane) for silicone composite reinforcement." Thesis, Stellenbosch : Stellenbosch University, 2011. http://hdl.handle.net/10019.1/17875.
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Thesis (PhD)--Stellenbosch University, 2011.ENGLISH ABSTRACT: Novel silicone nanocomposites were prepared using poly(acrylonitrile) (PAN) based reinforcing fibres as well as multi-walled carbon nanotubes (MWCNTs). Compatibility of the fibre fillers with the silicone matrix required the synthesis of novel amphiphilic, organic–inorganic graft copolymers of PAN and poly(dimethylsiloxane) (PAN-g-PDMS). These fibre precursor materials were synthesised via the “grafting through” technique using conventional free radical copolymerisation. The PDMS macromonomer content in the feed was varied from 5 wt% to 25 wt% and the molecular weights of the macromonomer were 1000 g.mol-1 and 5000 g.mol-1. The solvent medium of the precipitation reaction was optimised at a volume ratio of 98% benzene to 2% dimethylformamide (DMF). Successful incorporation of PDMS yielded graft copolymer blend materials of PAN-g-PDMS, blended with PAN homopolymer and unreacted PDMS macromonomer. A gradient elution profile was developed to track the successful removal of the PDMS macromonomer via hexane extraction. The gradient profile showed that as the PDMS content in the feed increased, the number of graft molecules in the blend increased relative to the number of PAN homopolymer molecules. The crystallisability of the PAN segments was shown to decrease as the PDMS content increased. The synthesised polymer was used as precursor material for the electrospinning of fibre fillers. The electrospinning of the precursor material was successfully achieved using 100% DMF as electrospinning solution medium. The amphiphilic nature of the precursor material in DMF resulted in self-assembled aggregate structures in the electrospinning solution. An increasing PDMS content was shown to affect the aggregation of the precursor material, and resulted in an increase in the solution viscosity. The “gel-like” solutions limited the achievable fibre morphological control when altering conventional electrospinning parameters such as voltage, tip-to-collector distance, and solution concentrations. The rapid evaporation and stretching of the solution during electrospinning, combined with the phase segregated amphiphilic molecules in solution and the crystallisation of the PAN segments resulted in (non-equilibrium morphology) fully porous fibres. The crystallinity was shown to decrease after electrospinning of the fibre precursor materials. Successful incorporation of surface oxidised MWCNTs into the electrospun fibres was achieved. The content of nanotubes was varied from 2 wt% to 32 wt%. The MWCNTs reduced the mean fibre diameters by acting as cross-linkers between the PAN segments and increasing the solution conductivity. The nanotubes dispersed well throughout the porous structure of the fibres and aligned in the direction of the fibre axis. Fabrication of silicone composites containing nonwoven and aligned fibre mats (with 8 wt% MWCNTs in the fibres, and without) was successfully achieved. The compatibilisation of the PDMS surface segregated domains allowed excellent dispersion and interaction of the PAN based fibre fillers with the silicone matrix. Mechanical analysis showed improved properties as the PDMS content in the fibre increased. The highest PDMS content fibres did, however, exhibit decreased properties. This was ascribed to increased PDMS (soft and weak) content, decreased crystallinity and increased fibre diameter (lower interfacial area). Dramatic improvements in strength, stiffness, strain and toughness were achieved. The most significant result was an increase in strain of 470%. The mechanical results correlated with results of SEM analysis of the fracture surfaces. The dramatic improvements in properties were a result of the fibre strength and ductility, as well as the mechanism of composite failure.
AFRIKAANSE OPSOMMING: Nuwe silikonnanosamestellings is berei deur gebruik te maak van poli(akrilonitriel) (PAN) gebaseerde versterkende vesels wat multi-ommuurde koolstof nanobuisies bevat het. Versoenbaarheid van die vesels met die silikonmatriks het die sintese van nuwe amfifiliese, organies–anorganiese ent-kopolimere van PAN en poli(dimetielsiloksaan) (PAN-g-PDMS) benodig. Die vesel voorlopermateriaal is deur middel van ‘n “ent-deur” vryeradikaalkopolimerisasie gesintetiseer. Die inhoud van die PDMS makromonomeer in die reaksie het gewissel vanaf 5% tot 25%. Die gebruik van twee verskillende molekulêre massas makromonomere is bestudeer (1000 en 5000 g.mol-1). Die optimale oplosmiddelmengsel vir die neerslagreaksie was 'n volume verhouding van 98% benseen tot 2% dimetielformamied (DMF). Suksesvolle insluiting van PDMS het versnitmateriale van PAN-g-PDMS kopolimere gemeng met PAN homopolimere en ongereageerde PDMS makromonomere gelewer. 'n Gradiënteluering- chromatografiese profiel is ontwikkel om die suksesvolle verwydering van die PDMS makromonomere via heksaanekstraksie te bepaal. Die gradiëntprofiel het aangetoon dat indien die PDMS inhoud in die reagense verhoog is, die aantal entmolekules relatief tot PAN homopolimeermolekules ook verhoog het. 'n Toename in PDMS inhoud het egter 'n afname in kristallisasie van die PAN segmente tot gevolg gehad. Die gesintetiseerde polimeer is gebruik as die beginmateriaal vir die elektrospin van veselvullers. Die elektrospin van die beginmateriaal was suksesvol wanneer 100% DMF as elektrospinoplosmiddel gebruik is. Die amfifiliese aard van die beginmateriaal in DMF lei tot outokonstruksie van aggregaatstrukture in die elektrospinoplossing. Toenemende PDMS inhoud beïnvloed die outokonstruksie van die molekules in oplossing en het gelei tot 'n toename in die oplossings se viskositeit. Die "gelagtige" oplossings beperk die haalbare vesel se morfologiese beheerbaarheid wanneer konvensionele elektrospin parameters soos elektriese spanning, punt-tot-versamelaar afstand, en oplossingkonsentrasies gewysig word. Die vinnige verdamping en strek van die oplossing tydens elektrospin, gekombineer met die fase-geskeide amfifiliese molekules in oplossing en die kristallisasie van die PAN segmente, het gelei tot (nie-ewewig morfologie) volledige poreuse vesels. Die kristalliniteit van die veselbeginmaterial het afgeneem nadat elektrospin toegepas is. Die insluiting van die oppervlak-geoksideerde multi-ommuurde koolstof nanobuisies in die elektrogespinde vesels was suksesvol. Die inhoud van die nanobuisies het gewissel van 2 wt% tot 32 wt%. Die MWCNTs het die gemiddelde veseldeursnit verminder deur op te tree as kruisbinders tussen die PAN segmente van die molekules. Die nanobuisies was goed versprei deur die poreuse struktuur van die vesels en dit was gerig in die rigting van die vesel-as. Bereiding van die silikonsamestellings bestaande uit nie-geweefde en gerigte veseloppervlakke (met en sonder 8 wt% multi-ommuurde koolstof nanobuisies in die vesel) was suksesvol. Die versoenbaarheid tussen die oppervlak van die PDMS-geskeide gebiede en die silikonmatriks laat uitstekende verspreiding en interaksie van die PAN-gebaseerde veselvullers met die silikonmatriks toe. Meganiese analise het aangetoon dat die fisiese eienskappe verbeter het namate die PDMS inhoud in die vesel vermeerder het. Die vesels met die hoogste PDMS inhoud het egter verswakte eienskappe getoon. Dit is toegeskryf aan ‘n verhoogde PDMS inhoud (sag en swak), ‘n afname in kristalliniteit en ‘n verhoogde veseldeursnit (laer grensoppervlakke). Dramatiese verbeterings in sterkte, styfheid, verlengbaarheid, vervorming en taaiheid is bereik. Die mees betekenisvolle gevolg was 'n toename in die verrekking van 470%. Die meganiese resultate is gekorreleer met SEM ontleding van die brekingsoppervlakke. Die veselkrag en vervormbaarheid, sowel as die meganisme van die splyting van die samestellings, het tot die dramatiese verbeterings in die meganiese eienskappe gelei.
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Gehring, Markus Verfasser], Rüdiger-A. [Akademischer Betreuer] [Eichel, Dirk Uwe [Akademischer Betreuer] Sauer, and Joachim [Akademischer Betreuer] Mayer. "Electrospun fibres as efficient cathodes for metal-air batteries / Markus Gehring ; Rüdiger-A. Eichel, Dirk Uwe Sauer, Joachim Mayer." Aachen : Universitätsbibliothek der RWTH Aachen, 2020. http://d-nb.info/122621858X/34.
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Both, Engel Adriana. "Development and optimization of electrospun carbon fiber electrodes designed for enzymatic or hybrid biofuel cells applications." Thesis, Montpellier, Ecole nationale supérieure de chimie, 2015. http://www.theses.fr/2015ENCM0022/document.
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Ce manuscrit de thèse présente la synthèse et l’optimisation d’un nouveau matériau d’électrode adapté aux biopiles enzymatiques et hybrides qui sont des systèmes capables de convertir de l’énergie chimique en énergie électrique en utilisant des catalyseurs enzymatiques. Ce matériau est constitué de nanofibres de carbone fabriquées par la technique d’electrospinning à partir d’une solution de polyacrylonitrile, suivi de traitements thermiques appropriés. Les propriétés structurales et électriques des nanofibres de carbone les rendent très intéressantes en tant que matériaux d’électrode tridimensionnels pour développer des systèmes de conversion d’énergie. Dans ce travail, afin d’améliorer ces propriétés, les nanofibres de carbone ont été synthétisées en les modifiant soit avec des nanotubes de carbone, soit in situ avec des particules d’or. D’autre part, l’influence de l’organisation spatiale des fibres a été étudiée avec la synthèse de fibres alignées et non alignées. La morphologie et la structure des fibres ont été caractérisées puis ces fibres ont été utilisées en tant que matériaux d’électrode modifiés par des enzymes oxydoréductases pour la réduction électrocatalytique de l’oxygène à la cathode. Des enzymes ont été encapsulées dans des matrices de Nafion, polypyrrole ou chitosan pour réaliser soit du transfert médiaté, soit du transfert direct. Pour la première fois, ces matériaux d’électrode ont été utilisés pour construire des biopiles enzymatiques et hybrides utilisant comme combustible soit de l’éthanol ou du glucose. Les résultats obtenus dans ce travail ont démontré les perspectives prometteuses des matériaux 3D à surface spécifique élevée pour améliorer les performances électriques des biopiles par rapport à des matériaux densesThis thesis manuscript presents the synthesis and optimization of a new electrode material suitable for enzymatic and hybrid biofuel cells, which are systems capable of converting chemical energy into electrical energy by using enzymatic catalysts. This material is composed of carbon nanofibers fabricated by the electrospinning of a polyacrylonitrile solution, followed by appropriate thermal treatments. Carbon nanofibers structural and electrical properties make them very suitable for application as tridimensional electrode materials for the development of energy conversion systems. In this work, aiming to improve these properties, carbon nanofibers were synthesized and modified either with carbon nanotubes, or in situ with gold particles. In a different strategy, the influence of the fibers spatial organization was studied through the synthesis of aligned and randomly organized fibers. Fibers structure and morphology were characterized, and then the fibers were employed as electrode materials modified with oxidoreductase enzymes for the reduction of oxygen at the cathode compartment. Enzymes were entrapped in matrixes composed of Nafion, polypyrrole or chitosan in order to realize either mediated or direct electron transfer. For the first time, these electrode materials were employed for the construction of enzymatic or hybrid biofuel cells, with ethanol or glucose as fuels. The results obtained in this work were able to demonstrate the promising perspectives of 3D materials with high specific surface to enhance the performance of biofuel cells, if compared to dense materials
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Maghdouri-White, Yas. "Mammary Epithelial Cells Cultured onto Non-Woven Nanofiber Electrospun Silk-Based Biomaterials to Engineer Breast Tissue Models." VCU Scholars Compass, 2014. http://scholarscompass.vcu.edu/etd/3358.
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Breast cancer is one of the most common types of cancer affecting women in the world today. To better understand breast cancer initiation and progression modeling biological tissue under physiological conditions is essential. Indeed, breast cancer involves complex interactions between mammary epithelial cells and the stroma, both extracellular matrix (ECM) and cells including adipocytes (fat tissue) and fibroblasts (connective tissue). Therefore, the engineering of in vitro three-dimensional (3D) systems of breast tissues allows a deeper understanding of the complex cell-cell and cell-ECM interactions involved during breast tissue development and cancer initiation and progression. Furthermore, such 3D systems may provide a viable alternative to investigate new drug or drug regimen and to model and monitor concurrent cellular processes during tumor growth and invasion. The development of suitable 3D in vitro models relies on the ability to mimic the microenvironment, the structure, and the functions of the breast tissue. Different approaches to develop a novel 3D breast model have been investigated. Most models use gel scaffolds, including Matrigel® and collagen to generate breast tissue-like structures. However, the physicochemical, mechanical, and geometrical properties of these scaffolds only partially meet the mechanical, physical, and chemical parameters of the breast tissue matrix. In the present studies, we investigated the overall hypothesis that electrospun SF-derived scaffolds promote mammary cell growth and the formation of mammary-like structures depending on the composition and/or coating of the scaffolds with ECM proteins. Through an extensive literature search (1) the importance of 3D modeling of tissues and organs in vivo, (2) 3D modeling of the mammary tissue and currently available models, (3) the properties and applications of SF in tissue modeling and regeneration were reviewed (Chapter 1). Our studies provide evidence of the effects of various concentrations (Chapter 2) of SF along with different electrospinning techniques (Chapter 3) on the structure of electrospun scaffolds and whether those scaffolds provide suitable microenvironments for mammary epithelial cells as determined by MCF10A cell attachment, viability, and structure formation. Further, we investigated the effects of the key ECM proteins collagen I (Chapter 4) and laminin (Chapter 5) used to blend or coat, respectively, SF scaffolds on the attachment, viability and structure formation of mammary epithelial cells. Our studies first highlight the mechanical and physical properties of the different SF-derived scaffolds through various SF concentrations and electrospinning techniques. Second, the biocompatibility of these SF electrospun scaffolds was defined based on MCF10A cell survival and adhesion. Third, our data indicate that scaffolds derived from blended and/or coated SF with collagen I also promoted human mammary cell survival and adhesion. Lastly, our observations suggest that on laminin-coated SF scaffolds MCF10A mammary cells, in the presence of lactogenic hormones, differentiated forming acinus-like structures. Overall, these studies provide evidence that SF electrospun scaffolds closely mimic the structure of the ECM fibers and allow many advantages such as; physical and chemical modification of the microenvironment by varying electrospinning parameters and addition of various proteins, hormones, and growth factors, respectively. Further, coating these SF scaffolds with essential ECM proteins, in particular laminin, promote cell-ECM interactions necessary for cell differentiation and formation of growth-arrested structures, through providing cell integrin binding sites and appropriate chemical cues.
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Gotti, Carlo. "Development and mechanical characterization of a biostable Nylon6.6 electrospun nanofibrous multiscale device for tendon and ligament replacement and simulation." Master's thesis, Alma Mater Studiorum - Università di Bologna, 2018. http://amslaurea.unibo.it/15708/.
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This thesis aims to investigate electrospun structures by means their production process and morpho-mechanical characterization. Considering the results obtained, the electrospun devices developed, will be useful for tendon and ligament tissue applications.
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Samanta, Archana. "Multifunctional electrospun fibrous scaffolds of pickering-high internal phase emulsions." Thesis, 2017. http://localhost:8080/xmlui/handle/12345678/7466.
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Chen, I.-Ting, and 陳奕廷. "The Study of Melting Electrospun Fibrous Membrane for Air Filtration." Thesis, 2016. http://ndltd.ncl.edu.tw/handle/26mfk3.
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碩士國立臺灣科技大學
材料科學與工程系
104
In this study, Polylactic acid (PLA)-based membranes were manufactured by the technique of melting electrospinning to explore the effect of filtration efficiency for different basis weight of fiber membrane, and applied to air filtration. The fiber diameter range of PLA fiber membranes approached 7.48 μm to 14.71 μm as the applied voltage reached corresponding optimum parameter. The porosity, pore size distribution, surface potential, and filtration efficiency were tested for fiber membranes. On the other hand, combining melting type electrospinning and solution type electrospinning to micro-nano electrospinning fiber membranes to explore the effect of filtration efficiency. The results show that, porosity was 92 %, pore size was 90 μm, surface potential was 2 kV after stabilization, filtration efficiency was 70 %, and pressure drop was 0.2 mmH2O for melting electrospinning fiber membranes. For micro-nano electrospinning fiber membranes, pore size was 11 μm, filtration efficiency was 96 %, and pressure drop was 6.5 mmH2O.
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Pereira, Andreia Leal. "Fibrous scaffolds from PCL/Chitosan blends for tissue engineering." Master's thesis, 2018. http://hdl.handle.net/10773/25806.
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The development of artificial structures (scaffolds), that mimic the extracellular matrix as closely as possible, and that aid in the regeneration of living tissues, has been one of the main areas of study in tissue engineering. Two-dimensional nanofibrous can be obtained by electrospinning, but three-dimensional structures are very difficult to obtain directly by electrospinning. Because of that, a group of researchers recently developed a technique called Thermally Induced Self-Agglomeration (TISA) that allows transforming two-dimensional electrospun membranes into three-dimensional structures. The objective of this work was to produce and characterize electrospun membranes of PCL/chitosan blends, to then convert them into 3D structures by TISA, followed by freeze drying. The obtained products were nanofibrous 3D scaffolds with increasing amounts of chitosan (10, 15 and 20%), highly porous (>90%) and with interconnected pores of different sizes. Compression modulus indicated compatibility for cartilage tissue engineering. The results demonstrated that the obtained scaffolds presented high similarity both in morphology and properties to the natural extracellular matrix. Therefore, its application in tissue engineering should be very promisingO desenvolvimento de estruturas artificiais (scaffolds), que imitem, o mais perfeitamente possível, a matriz extracelular, e que auxiliem na regeneração dos tecidos vivos, tem sido uma das principais áreas de intervenção em engenharia de tecidos. Arquiteturas nanofibrosas bidimensiomais podem ser obtidas por electrofiação (electrospinning), enquanto que estruturas tridimensionais são muito difíceis de obter diretamente pelo mesmo método. Posto isto, um grupo de investigadores, recentemente desenvolveu uma técnica chamada Thermally Induced Self-Agglomeration (TISA) que permite transformar membranas bidimensionais obtidas por electrofiação em estruturas tridimensionais. Este trabalho teve como objetivo, produzir e caracterizar, membranas por electrofiação de uma mistura de PCL/quitosano, para a seguir convertê-las em estruturas 3D por TISA, seguida de liofilização. Os produtos obtidos foram scaffolds 3D nanofibrosos com crescentes quantidades de quitosano (10, 15 e 20%), altamente porosos (>90%) com poros interconectados de variados tamanhos. Módulos de compressão indicaram compatibilidade para engenharia de tecidos da cartilagem. Os resultados mostraram que os scaffolds apresentavam alta similaridade tanto na morfologia como nas suas propriedades com a matriz extracelular natural e que por isso, a sua aplicação em engenharia de tecidos deverá ser bastante promissora
Mestrado em Materiais e Dispositivos Biomédicos
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Wu, Hsin-Ping, and 吳馨蘋. "A Study of Electrospun PLA Nano-fibrous Membrane Applied in HEPA Filter." Thesis, 2014. http://ndltd.ncl.edu.tw/handle/z9zceq.
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碩士國立臺灣科技大學
材料科學與工程系
102
In this study, the Polylactic acid (PLA)-based membranes were manufactured by the technique of electrospinning. The BET characteristics of the nano-fibrous membranes had ultra-high surface area of fine and uniform pores. PLA is refined from a corn, which has great environmental characteristics and can be decomposed in the nature. With the above those characteristics, the PLA-based membranes are applied in the high efficiency particulate air (HEPA) filter. However, due to the lower strength of nano-fibrous membrane, the spunbond nonwoven was devised as a reinforcement material and combined the nano-fibrous membrane. It is a multi-layers filter material named Spunbond-Electronspun-Spunbond (SES) composite membrane. The fiber diameter range of the PLA-based membranes approached 658nm~954nm as their spinning dope concentrations and flow rates reached their corresponding optimum values. To understand tensile properties, porosity, pore size, filtration efficiency and SEM morphology analysis of PLA-based membranes were performed in this study. Experimental results show that, as the PLA concentration and roller speed decreases, the fiber diameter and strength tensile increases. The tensile strength value is 1.66 kgf of PLA-based membranes prepared using the optimum spinning dope concentration of 8wt%. Furthermore, even better filtration efficiency can be obtained for PLA-based membranes with optimum spinning dope concentration and even higher roller speeds. When the roller speed is increased, the pore size is increased, and when the PLA concentration and roller speed decreases. The results infer that by controlling the experimental parameters will expect to obtain the best performance of SES, which can remove 99.97% of airborne particles 0.05 micrometers (μm) and 100.00% of airborne particles 0.2 micrometers (μm).
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Wu, Meng-Che, and 吳孟哲. "Real-time and indicator-free detection of aqueous nitric oxide with electrospun fibrous membrane." Thesis, 2009. http://ndltd.ncl.edu.tw/handle/90514160813415564052.
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碩士國立交通大學
物理研究所
97
Nitric oxide (NO) is a free radical playing important roles in the human body. NO relaxes the smooth muscle in the walls of the arterioles, regulates the blood pressure, and inhibits the aggregation of platelets.1–4 It also serves as a signaling molecule in the nervous system.5 Direct and real-time detection of NO outside the cell helps to unveil how NO relates to certain physiological function. Since the beginning of 20 century, electrospinning had been developed Electrospinning is a process, which produces superfine fibers. Electrospinning is able to produce continuous fibres from the submicron diameter down to the nanometre diameter. A sensing fibrous membrane prepared by electrospinning is demonstrated for real-time and indicator-free detection of nitric oxide (NO) in aqueous solution. The fibers with diameters of 550 nm are composed of NO probe 11,16-Bisphenyl-6,6,21,21-tetramethyl-m-benzi-6,21-porphodimetheno-chloro-Zinc(II) and host polymer polyacrylonitrile. The high surface area of the sensing fibrous membrane gives rapid response in 6 seconds and high sensitivity, and NO concentration detection limit is estimated to be 10−9 M. The sensing fibrous membrane also shows good reversibility, selectivity, and stability in various pH values.
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Huang, Li-Ping, and 黃莉萍. "Fabrication and characterization of electrospun alginate/polycaprolactone composite fibrous scaffolds for skin wound dressing." Thesis, 2011. http://ndltd.ncl.edu.tw/handle/56255565115189721980.
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碩士中原大學
化學工程研究所
99
The three-dimensional structure of the electrospun scaffolds which can mimic the physical structure of the extracellar matrix (ECM), and it could support the environment for cell growth. Nature polymer-sodium alginate (SA) and synthetic polymer-polycaprolactone (PCL) with excellent biodegradability and biocompatibility were widely used as a biomimetic artificial scaffold in tissue engineering. In this study, we induced two types of polymer which were fabricated the SA/PCL composite fibers by electrospinning. The composite fibrous scaffold could not only support the cell growth, but also have the ability to accelerate the wound healing. Besides, SA fiber could absorb the exudates of wound, and keep a moist interface on the wound surface, hemostatic properties etc. At first, we fabricated PCL and alginate fiber without bead by electrospinning. The effect of spinning conditions on the electrospinning fiber morphology were investigated, the spinning conditions including the cosolvent composition, molecular weight, concentration, polymer blending ratio, applied voltage and working distance. And the uniformity of fibers was improved with controlling the feed flow rate. Then the composite fibers were crosslinking to keep the structure integrity in an aqueous medium. The alginate/PCL composite fibers were characterized through tensile test and water uptake ability. The cellular biocompatibility and hemostatic property of the composite scaffold were evalutated by the in vitro cell culture and the clotting time test, respectively. The results showed that the bead-free structure on alginate and PCL fibers were successfully fabricated under the optimal spinning conditions, and the uniformity of fibers were also improved with controlling the feed flow rate. The average fiber diameter of the alginate and the PCL fiber is 0.39±0.07 m and 1.38±0.19 m, respectively. Then the composite scaffold was successfully crosslinking through Ca2+ ions, and the fibrous structure will stability in the aqueous medium. The results of tensile test were indicated that it was no significant difference between the PCL fibers and SA/PCL composite fibers. The ultimate tensile stress and tensile strain are ~1.7 MPa, 300% for both PCL and SA/PCL composite fibers, respectively. Inversely, the water uptake capacity of SA/PCL composite fibers was remarkably higher than PCL fibers which could facilitate the wound-healing by absorbing the exudates of wounds. When seeding the human fibrosarcoma cells (HT1080) on the scaffolds, in vitro MTT assay results indicated the electrospun scaffolds have excellent biocompatibility and without cytotoxicity. In addition, the clotting time test with whole blood showed that SA/PCL composite fibers have the good coagulant property compared with PCL fibers, PCL film and TCPS as control. The cytocompatibility and blood compatibility analyses proved the SA/PCL composite fibers have the great potential to develop a novel biomaterial on wound dressing applications.
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Jinasena, Isuru Indrajith Kosala. "Electrospun nano-mat strengthened aramid fibre hybrid composites : improved mechanical properties by continuous nanofibres." Thesis, 2016. http://hdl.handle.net/10539/22603.
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Department of Mechanical, Industrial and Aeronautical Engineering
MSc (Mechanical Engineering)Aramid fibre reinforced epoxy composites were hybridised by the addition of electrospun PAN (polyacrylonitrile) and ECNF (electrospun carbon nanofibre) doped PAN nanomats. One of the major concerns in polymer composites is the effect of the interlaminar properties on the overall mechanical properties of the composite. Electrospun carbon nanofibres were used as doping agents within PAN nanofibres, and coated in between aramid epoxy laminates to improve the interlaminar properties. PAN nanomats and ECNF doped PAN nanomats were created by the use electrospinning on the surface of aramid fibre sheets. Multiscale hybrid aramid reinforced composites were then fabricated. Mechanical characterization was carried out to determine the effect of PAN and CNF doped PAN nanofibre mats on aramid fibre reinforced epoxy. It was found that PAN reinforced nanomats had improved the mechanical properties and more specifically, when doped by ECNFs, the volume fraction of ECNFs played a vital role. An addition of 1% vol. CNF doped 0.1% vol. PAN reinforcement within a 30% vol. aramid fibre composite (control composite), improved the tensile strength and elastic modulus by 17.3% and 730% respectively. The 0.5% vol. PAN reinforced AFC (aramid fibre composite) specimens revealed a major increase in the flexural strength by 9.67% and 12.1%, when doped by both 0.5% vol. ECNFs and 1% vol. ECNFs respectively. The 0.5% vol. CNF doped reinforcement increased the impact energy by over 40%, for both the 0.1% vol. and 0.2 % vol. PAN reinforced aramid hybrid specimens. The 0.5% vol. CNF doped 0.5% vol. PAN had increased by 30% when compared to a non-doped sample. Morphological studies indicated interlaminar shearing between plies was affected by CNF agglomerations. This was discovered when determining the impact properties of the multiscale doped hybrid composites. Electrospun nanofibres however, assisted in improving the interlaminar regions within aramid epoxy by mechanical locking within the epoxy, and creating an adhesive bond using Van der Waals forces and electrostatic charges between nanofibre and macro fibre. Hybridising aramid epoxy with the use of nanofibres assisted in improving various mechanical properties. Impact degradation was one disadvantage of hybridising using CNF doped PAN nanofibre reinforcements.
MT2017
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Wang, Sheng Chuan, and 王生銓. "Clearance of Uremic Toxins from Simulated Serum Using Electrospun and Electrosprayed Cellulose Triacetate Fibrous Membrane." Thesis, 2019. http://ndltd.ncl.edu.tw/cgi-bin/gs32/gsweb.cgi/login?o=dnclcdr&s=id=%22107CGU05063030%22.&searchmode=basic.
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Yang, Shao-Pei, and 楊劭珮. "Evaluations of electrospun γ-PGA fibrous mats combined with β-tricalcium phosphate powder for bone regeneration." Thesis, 2015. http://ndltd.ncl.edu.tw/handle/eyf789.
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Chang, Liang-Yu, and 張良宇. "Grafting polymerized N-isopropylacrylamide into electrospun polycarbonate fine-fibrous membrane as a matrix for cells culture." Thesis, 2008. http://ndltd.ncl.edu.tw/handle/36693589790348591782.
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碩士臺北醫學大學
生物醫學材料研究所
96
In this study, the electrospinning technique was utilized, and polycarbonate was used to fabricate fine-fibrous membrane. We also prepared membranes with different features by controlling factors (different concentration in solute, feeding rate, changes in voltage).To investigate more strong and more highly porosity PC membrane, the PC membrane was treated by plasma to change the property of the surface . After the modification, poly(N-isopropylacrylamide)PIPAAm grafted in PC membrane for used in cell culture. The structure and morphology of electrospun membranes were investigated by scanning electron microscope (SEM), pore size measuring, and contact angle detector. NIH 3T3 was cultured on the modified membrane to observe the cell morphology, attachment, and proliferation. The 12.5%(wt/V) PC solution contain a mixture solvent of Dichloromethane, Methanol, Acetone, 1-4’dioxane(80:10:2:8) and the feeding rate keeps in 0.08ml/min. The solution was electrospun into non-woven fiber mesh with fiber diameter ranging from 1.1 to 2,5μm and pore size was measured 3~8μm. PNIPAAm was immobilized onto PC non-woven surface. This composites material was considered to replace the PET membrane in trans-well insert. While going to cell culture with this composites material, we can get cells called “cell sheet engineering” not like usual cell suspension. The cell cultured by this new technology will proceed detachment without any enzyme and own ECM(extra cellular matrix) to keep their 3D scaffold while growing up.
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Chen, Sheng-Han, and 陳聖翰. "Study on the structure of electrospun chitosan/ poly(DL-lactide) composite fibrous scaffold for human fibrosarcoma cells (HT1080) attachment and proliferation." Thesis, 2010. http://ndltd.ncl.edu.tw/handle/29700187425549394987.
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碩士中原大學
化學工程研究所
98
In this study, the effect of morphology design of chitosan/ poly(DL-lactide) electrospun composite fibrous scaffold on the attachment and proliferation of human fibrosarcoma cells (HT1080)were investigated. The bead-free and the most uniformity of PDLLA fibers could be fabricate through adjusting spinning parameters, e.g. under the condition of polymer concentration: 15wt%, working distance: 30 cm and needle diameter: 0.16 mm. Otherwise, the degradation test of chitosan spunning solution were also investigated. The result showed that the viscosity of chitosan solution decrease with increasing the degradation time. After 10 days of degradation, the spinnability and morphology of chitosan fibers were dramatically improved. The better alignment of chitosan fibers were collected successfully at 1000 rpm of rotating-drum collector. MTT assay results indicated the 3D structure of chitosan/ PDLLA composite fibrous scaffold could promote the ability of human fibrosarcoma cells proliferation compare with the 2D structure of PDLLA film and cover slip. When the collecting amount of chitosan aligned fibers increased to 12.66 g/cm2, the growth of cells were guided and elongated by the aligned chitosan fibers. And the 3D conforcal images showed that the cell growth could infiltration to the inside of fibrous scaffold, it’s consistent with the structure design of chitosan/PDLLA composite fibrous scaffold. According to the principle of tissue engineering, chitosan/PDLLA composite fibrous scaffold could have excellent potential for tissue regeneration and wound healing applications in the future.
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Casanova, Marta Alexandra Rodrigues. "Surface biofunctionalization of polycaprolactone fibrous meshes for skeletal and neural tissue advanced therapies." Doctoral thesis, 2020. http://hdl.handle.net/1822/76802.
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Tese de Doutoramento em Engenharia de Tecidos, Medicina Regenerativa e Células EstaminaisDamage of the skeletal and neural tissues has a significant impact over the quality-of-life of patients and high socio-economical costs. Current treatment options are not effective in long term, due to the suboptimal integration with the host tissue and limited bioactivity of implantable biomaterials. The immobilization of biomolecules at the surface of biomedical devices has attracted increasing interest, allowing for their local bioavailability avoiding systemic side effects and longer half-life. Envisioning the development of advanced therapies, the electrospun nanofibrous meshes (NFMs) were used as a substrate due to their fibrous structure mimic the extracellular matrix (ECM) of many tissues, allowing cell-cell and cell-biomaterial interactions. For that, the surface of polycaprolactone NFMs was activated and functionalized with amine groups allow for covalent immobilization of defined antibodies, with the capacity to selectively bind autologous biomolecules. Different biofunctional substrates with chondrogenic inductive properties were developed through the surface biofunctionalization of NFM with endogenous human fibronectin, extracellular vesicles or the combination of endogenous Transforming Growth Factor-133 and Insulin-like Growth Factor-I. All these biofunctional substrates successfully induced the chondrogenic differentiation of human bone marrow-derived mesenchymal stem cells (hBM-MSCs) under basal culture conditions. Blood-derived Nerve Growth Factor bound to the surface of NFMs remains bioactive, being an effective inducer of the neurogenic differentiation of a relevant cell line. Additionally, we developed a biofunctional system able to mimic the vasculature of bone tissue, comprising Bone Morphogenetic Protein 2 and Vascular Endothelial Growth Factor in a parallel pattern design. This biofunctional system enabled a spatially defined osteogenic and angiogenic differentiation of hBM-MSCs. The surface biofunctionalization of biomaterial substrates enables developing biofunctional systems envisioning patient-specific devices promoting skeletal and neural tissue regeneration that can maximize and extend the local efficacy and minimize the side effects of the use of biologic based therapies in patients.
A deterioração dos tecidos esquelético a neural têm um impacto significativo na qualidade de vida dos pacientes e um elevado custo socioeconómico. Os tratamentos atualmente disponíveis não são eficazes a longo termo, devido à inadequada integração com o tecido hospedeiro e à baixa bioatividade dos biomateriais implantados. A imobilização de biomoléculas constitui uma estratégia alternativa, permitindo a biodisponibilidade local das biomoléculas evitando efeitos colaterais sistêmicos. Ambicionando desenvolver terapias avançadas, malhas fibrosas produzidas por "electrospinning" (NFMs) foram usadas como substratos poliméricos devido à sua estrutura fibrosa similar a matriz extracelular (ECM) de muitos tecidos, promovendo as interações célula-célula e célula-biomaterial. Para isso, NFMs de policaprolactona foram ativadas e funcionalizadas com grupos amina, permitindo a imobilização covalente de anticorpos pré-definidos, com capacidade de ligar seletivamente biomoléculas autólogas. Foram desenvolvidos diferentes substratos biofuncionais, com propriedades indutoras de diferenciação condrogénica, mediante ligação de fibronectina humana, vesículas extracelulares ou a combinação do fator de transformação do crescimento beta 3 com o fator de crescimento semelhante à insulina tipo I. Todos estes substratos biofuncionalizados foram capazes de induzir a diferenciação condrogénica de células estaminais mesenquimais derivadas de medula óssea humana (hBM-MSCs) sendo cultivadas em condições basais. O fator de crescimento nervoso ligado à superfície das NFMs permanece bioativo, sendo um indutor eficaz da diferenciação neurogénica de uma linha celular relevante. Numa outra abordagem, foi desenvolvido um sistema biofuncional capaz de mimetizar a vasculatura de um tecido ósseo, ligando paralelamente a proteína morfogenética óssea 2 e o fator de crescimento do endotélio vascular sobre uma mesma NFM. Este sistema biofuncional permitiu a diferenciação osteogénica e angiogénica de hBM-MSCs espacialmente definida. Concluindo, a bioftmcionalização de substratos produzidos por "electrospinning" permite o desenvolvimento de dispositivos biomédicos personalizados, capazes de promover a regeneração do tecido esquelético e neural, maximizando a eficácia local e minimizando os efeitos colaterais do uso de terapias biológicas em pacientes.
To the financial support of the Portuguese Fotmdatron for Science and Technology to maize possible this PhD by awarded me with a PhD scholarship (PD/BD/113797/2015) under the Doctoral Program on Advanced Therapies for Health (FSE/POCK/PD/169/2013). The experimental work was funded by the projects SPARTAN (PTDC/CTM-BIO/4388/2014) and FRONthera (NORTE-01-0145-FEDER-0000232).
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Lin, Cheng Jie, and 林承潔. "A study of the effect of molecular-scale topography of collagen and gelatin electrospun fibrous on thephenotype and proliferation of MG63 osteoblast-like cells." Thesis, 2009. http://ndltd.ncl.edu.tw/handle/11377207996360313668.
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碩士長庚大學
生化與生醫工程研究所
98
Recently, electrospinning is one of the popular techniques to manufacture nanofibrous scaffolds for tissue engineering. It has been known that fluorinated alcohols such as 1, 1, 1, 3, 3, 3– hexafluoroisopropanol (HFIP) is a good solvent for polypeptide biopolymers such as collagen, gelatin et al. Unfortunately, most of the studies of electrospinning of pure collagen or hybrid collagen with other polymers out of fluoroalcohols showed the structure of collagen matrix is similar gelatin matrix on molecular-scale. Therefore, in the present work, we evaluate the effect of molecular-scale topography of electrospun collagen and gelatin nanofibril matrix on the morphology, proliferation and differentiation of MG-63 osteoblast-like cells. The results shown that the cells attached to the collagen matrix primarily showed with more extending pseudopodium rather than on the gelatin matrix. Moreover, the MG63 cells showed a higher proliferation rate on the collagen matrix than on gelatin matrix. Further, reverse transcription polymerase chain reaction (RT-PCR) analysis showed different osteogenic gene expression of osteocalcin, ostepontin and type I collagen between cells differentiated on collagen and gelatin electrospun nanofibers. In addition, the MG63 cells showed higher expression of OCN cultured on the electrospun collagen matrix than on electrospun gelatin matrix at day 7. Together the results indicate that even though the fluorinated alcohols disrupted the unique structure of collagen molecules, but there is still different performance of MG63 cells on the electrospun collagen and electrospun gelatin matrix.
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Girão, André Francisco Oliveira. "Selective functionalization of electrospun fibres." Master's thesis, 2013. http://hdl.handle.net/10451/10724.
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Tese de mestrado integrado em Engenharia Biomédica e Biofísica, apresentada à Universidade de Lisboa, através da Faculdade de Ciências, 2013A engenharia de tecidos é uma área multidisciplinar da engenharia biomédica que articula conceitos da química, física, engenharia e medicina com o objetivo de recuperar ou substituir uma função perdida de determinado órgão ou tecido. Um dos principais desafios desta área da biotecnologia é a criação de matrizes tridimensionais biocompatíveis e biodegradáveis que sejam capazes de garantir um suporte físico e bioquímico adequado à regeneração celular. Assim, as características mecânicas, químicas e biológicas destas matrizes devem ser adaptadas ao ambiente celular que se pretende reproduzir, dando origem quer à resposta celular específica das células cultivadas na matriz, quer à otimização da resposta fisiológica do próprio organismo. Com efeito, dependendo da função a que se destina, as matrizes usadas em engenharia de tecidos variam tanto no biomaterial que lhes dá origem como na técnica de fabricação utilizada. As vantagens dos polímeros face aos outros materiais tais como biocompatibilidade, biodegradação, alta porosidade e boas propriedades mecânicas, tornam-nos no tipo de material mais utilizado na construção de matrizes tridimensionais. É o caso do copolímero PolyActive, já aprovado pela Food and Drug Administration (FDA) e utilizado em múltiplas aplicações em engenharia de tecidos, com especial destaque para a regeneração óssea. A versatilidade deste polímero está estreitamente relacionada com o rácio dos segmentos químicos que o constituem, um segmento hidrofílico de Politereftalato de etileno (PEOT) e outro hidrofóbico de Poli(tereftalato de butileno) (PBT), que ao ser modificado permite o controlo das propriedades mecânicas e químicas do material. Por outro lado, a eletrofiação é uma técnica de fabricação que tem crescido em termos de popularidade pois permite o fabrico de matrizes fibrosas capazes de simular detalhadamente a topografia das fibras de colagénio que compõem a matriz extracelular natural. Tendo tudo isto em conta, neste estudo foram construídas matrizes tridimensionais de PolyActive por eletrofiação capazes de modular e guiar a resposta celular a partir de recursos topográficos e bioquímicos. A topografia das matrizes foi controlada com a introdução de elétrodos capazes de influenciar o campo elétrico e, assim, alinhar as fibras de PolyActive durante o processo de eletrofiação, que ocorreu num ambiente controlado para garantir a reprodução das propriedades das fibras. Já a incorporação de biomoléculas na superfície das fibras foi conseguida a partir da investigação de duas estratégias distintas. Numa das abordagens, matrizes fibrosas de dois tipos de PolyActive (1000PEOT70PBT30 e 300PEOT55PBT45) foram expostas a irradiação ultravioleta (UV) com o objetivo de introduzir grupos químicos na superfície das fibras capazes de aumentar a adesão de biomoléculas. As diferenças entre superfícies tratadas e não tratadas com UV foram analisadas com recurso às técnicas de espetroscopia de infravermelho médio com transformada de Fourier acoplada ao acessório de reflexão total atenuada (ATR-FTIR) e de fotoeletrões excitados por raios X (XPS). Os resultados mostram que os grupos funcionais resultantes da interação da superfície das fibras com o UV dependem do rácio PEOT/PBT e do conteúdo de Polietilenoglicol (PEG) presente no copolímero. Assim, as fibras de 1000PEOT70PBT30 (PA 1000) apresentaram um grande número de grupos carboxilo e hidroxilo na sua superfície devido à degradação do segmento de PEOT e da sua grande cadeia polimérica de PEG após 40 minutos de exposição à radiação UV. Por sua vez, a matriz fibrosa de 300PEOT55PBT45 (PA 300), quando sujeita ao mesmo período de irradiação UV, originou p-benzoquinonas na superfície das suas fibras devido ao alto teor cristalino da sua estrutura. Em ambos os casos, o tratamento UV aumentou as áreas de adesão das proteínas oriundas do meio de cultura celular e por conseguinte a adesão celular tornou-se também mais eficiente. Porém, a resposta celular é dependente não só das características das matrizes, mas também da linha celular utilizada. Por exemplo, as células Schwann de rato mostraram não só preferência pelas áreas ativadas pelo UV, mas também se mostraram sensíveis a pequenas alterações do alinhamento das fibras resultantes das diferenças entre os dois copolímeros. Foi também utilizada uma máscara de níquel para controlar espacialmente a introdução de novos grupos químicos nas superfícies das matrizes fibrosas de PA 300 e PA 1000. A segunda estratégia apresentada consistiu na eletrofiação de fibras de PA 300 com grupos químicos incorporados para uma funcionalização posterior. Basicamente, uma solução polimérica composta por PA 300 e PEG com determinados grupos funcionais numa proporção 4:1 foi sujeita ao processo de eletrofiação, originando fibras de PA 300 com os grupos funcionais do PEG na sua superfície. Esta abordagem inovadora e inédita possibilitou a seleção dos grupos funcionais localizados na superfície das matrizes fibrosas e consequentemente o controlo do tipo de biomoléculas que vão aderir às fibras. Neste estudo foram utilizados dois tipos de PEG funcionalizado: PEG com terminais alcinos ((bis)PEG-Alkyne), que possibilitam a cicloadição azida-alcino com biomoléculas que tenham a função azida; e PEG com grupos terminais de N-hidroxisuccinimida ((bis)PEG-SVA), que facilitam a ligação com proteínas. As superfícies das matrizes de PA 300 + (bis)PEG-SVA e de PA 300 + (bis)PEG-Alkyne foram analisadas recorrendo às técnicas de ATR-FTIR e XPS. No primeiro caso, os resultados provaram a existência de N-hidroxisuccinimida na superfície das fibras, que depois foi confirmada com recurso a microscopia de fluorescência; relativamente às matrizes de PA 300 + (bis)PEG-Alkyne, apesar das técnicas de espectrometria não produzirem resultados conclusivos, foi possível confirmar a presença de alcinos na superfície das fibras a partir das imagens de microscopia de fluorescência. O sucesso da segunda abordagem permite abrir as portas ao aparecimento de novas metodologias de design e fabricação de matrizes biofuncionais, já que torna possível a simulação e controlo do ambiente bioquímico que influencia as respostas celulares de uma forma simples e eficiente.
The principal objective of a new generation of tissue engineering scaffolds is to reproduce the spatial and biochemical microenvironmental characteristics of the natural extracellular matrix (ECM) with the purpose of modulating the cell response and consequently enhance tissue repair. There is an enormous variety of scaffolding approaches that highly depend on the biomaterial selection, on the fabrication technique used and on the specific function of the scaffold. In this study, bioactive electrospun scaffolds made of PolyActive (Poly(ethylene oxide terephthalate) / Poly(buylene terephthalate) (PEOT/PBT)) copolymer, capable of combining a spatially organized structure with bioactive factors, was developed. The design and fabrication strategies used to create the scaffolds allow the tailoring of the scaffold’s function by manipulating the introduction of specific chemical groups on its surface for further selective immobilization of complex biomolecules, resulting in the desired cell response. In one approach, the surface of both 300PEOT55PBT45 (PA 300) and 1000PEOT70PBT30 (PA 1000) electrospun fibres were modified via UV exposure, resulting in the introduction of specific functional groups able to improve the protein adsorption process and consequently increase the available areas for cell attachment. A spatial definition of protein adsorption was accomplished by exposing the fibres via patterned mask. An alternative strategy consisted of electrospinning PA 300 fibres with incorporated chemical groups for later functionalization. Alkyne and NHS-esters functional groups were successfully incorporated on the surface of the electrospun fibres via the introduction of specific PEG linkers ((bis)PEG-alkyne and (bis)PEG-SVA) in the electrospinning blend solution. This innovative methodology can be adopted for multiple tissue engineering applications since specific chemical groups can be introduced onto the surface of electrospun fibres, leading to a meticulous selection of the biochemical elements that will be adsorbed and consequently to a detailed control of the cell behaviour.
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Fang, Yu-lin, and 方育林. "Electrospun of silk fibroin/chitosan immersed Shikonins for wound dressing." Thesis, 2013. http://ndltd.ncl.edu.tw/handle/93486835407915308193.
Full textAbstract:
碩士國立臺灣科技大學
材料科學與工程系
101
In the study, silk fibroin (SF) and chitosan (CS) mat was prepared by electrospinning technique, followed by immersing in shikonin solution to evaluate the feasibility of these mats for wound dressing. SF/CS nanofibers provided a better level of equilibrium water content (EWC) and water vapor transmission rate (WVTR). Antioxidant activity of shikonin-loaded SF/CS mats was measured by the DPPH assay. Cytotoxicity of shikonin-loaded SF/CS mat was evaluated using L929 and A375-S2 fibroblasts through the MTT assay. The antibacterial activity of shikonin-loaded SF/CS mat was evaluated against E coli and S. aureus. Through characterization of physical properties, stability testing, and biocompatibility, the shikonin-loaded SF/CS mat exhibited potential for wound dressing applications.
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Paredes, Carolina Teixeira. "Biocompatible silk fibroin electrospun matrices for in vitro cell culture." Master's thesis, 2018. http://hdl.handle.net/10348/8442.
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Skin is the largest organ of the human body, being crucial on its protection from foreign objects and microorganisms thus playing an important role for the homeostasis of the organism. It is composed by three layers, epidermis, dermis and hypodermis that together form the outmost layer of the body. Once this layer is damaged, human life could be at risk. The lack of viable donors leads to the urgency of developing skin substitutes. One of the strategies proposed by Tissue Engineering for the treatment of skin lesions is the development of skin substitutes made by natural or synthetic polymer or even a blend of both. Silk fibroin is a natural polymer with good biocompatibility and profiles already explored in the literature. Scaffolds based on this natural polymer have attracted great attention on the last decades due to its characteristics for tissue engineering (TE) applications. In the present work, silk fibroin based scaffolds were obtained through electrospinning processing technique, using silk fibroin solutions with a concentration of 12% (w/v) and formic acid as spinning solvent. Silk fibroin electrospun matrices were further treated with methanol at different concentrations and incubation times (50% (v/v), 75% (v/v), 100% (v/v) with a time length of 10 and 60 minutes each). The physico-chemical properties of silk fibroin were investigated, as well as human fibroblast cellular behavior (cytotoxicity and adhesion assays). The results demonstrated that the electrospun membranes treated with different methanol concentrations present β-sheet conformation, high water vapor transmission rate, similar to the control group, which is regarded as a crucial parameter for wound dressing. Cytotoxicity of the silk fibroin electrospun meshes was evaluated using hDNFs showing normal metabolic activity. We were able to successfully produce silk fibroin electrospun matrices that demonstrated no cytotoxic effect and presented suitable characteristics for the use in the context of skin regeneration.A pele é o maior órgão humano, crucial na proteção do corpo humano de objetos prejudiciais e microrganismos. Figurando como principal responsável pela homeostasia do organismo, é composto por três camadas, epiderme, derme e hipoderme, as quais em conjunto formam o revestimento mais externo do corpo. Quando danificada a vida humana pode estar em risco. A falta de dadores viáveis leva à necessidade de desenvolver substitutos para a pele. Neste contexto, a Engenharia de Tecidos, surge como uma tecnologia promissora para o tratamento de lesões a nível cutâneo através do desenvolvimento de substitutos produzidos a partir de polímeros naturas, sintéticos ou uma mistura dos dois. Fibroína de seda é um polímero natural, que apresenta elevada biocompatibilidade e biodegradabilidade. Scaffolds com base neste polímero natural, têm atraído considerável atenção nas últimas décadas devido às suas características para aplicações em Engenharia de Tecidos. No presente trabalho, scaffolds à base de fibroína de seda foram obtidos através do método de electrofiação. Com este objectivo, foram utilizadas soluções de fibroína de seda com uma concentração de 12% (w/v) em ácido fórmico. Matrizes de fibroína de seda, obtidas através do método de electrofiação, foram posteriormente tratadas com metanol em diferentes concentrações (50% (v/v), 75% (v/v),100% (v/v)) durante 10 e 60 minutos. As propriedades físico-químicas da fibroína de seda foram estudadas e o seu comportamento celular investigado através de ensaios de cito-toxicidade e de adesão celular. Os resultados demonstraram que, após o tratamento com metanol, as membranas apresentavam conformação β-folheada, taxas de transmissão de vapor de água elevadas, semelhantes ao grupo de controlo, figurando como um parâmetro fundamental no tratamento de feridas. A cito-toxicidade das membranas de fibroína de seda foi avaliada através da utilização de hDNFs, apresentando boa atividade metabólica. Conseguiu-se produzir, de forma bem sucedida, matrizes de fibroína de seda através do método de electrofiação, que não demonstraram efeitos cito-tóxicos e apresentavam características apropriadas para o uso no contexto de regeneração da pele.
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Zhang, Jun Tang, and 張均堂. "Fabrication and Characterization of Electrospun Silk Fibroin/Nylon 6 Nanofibrous Mats." Thesis, 2013. http://ndltd.ncl.edu.tw/handle/11678127005313781203.
Full textAbstract:
碩士中華科技大學
健康科技研究所
101
Silk fibroin (SF) and nylon 6 nanofibrous mats were fabricated via electrospinning process. Solutions of 10% w/v SF with 12% w/v nylon-6 were blended in different weight ratios and electrospun into nanofibers. The resulting mat was further rearranged from random coil to -sheet structure of SF through acetone-treating. The morphology, structure and mechanical properties of the obtained electrospun fibrous mats were characterized using scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FTIR), thermogravimetric analysis (TGA) and tensile testing, respectively. Infrared spectra showed that the β‐sheet structure of the silk fibroin increased after acetone treatment. SEM images showed that the morphology and diameter of the SF/nylon 6 nanofibrous mats were mainly affected by the weight ratios of the blend solutions. The results indicated that with increasing the amount of nylon 6 (from 0 % to ∼100%), the average diameter was increase from 480 nm to 600 nm and the tensile strength increased from 0.3 MPa to 6.3 MPa. Moreover, the equilibrium water content and water vapor transmission rate of the SF/nylon 6 nanofibrous mats were improved in compared with the nylon 6 increasing in the blend solutions. The attachment and proliferation properties of L929 fibroblast cells on the SF/nylon 6 nanofibers were analyzed by the MTT assays. Cytotoxicity tests of the SF/nylon 6 nanofibers showed that the fibers were non-toxic to L929 fibroblast cells. Therefore these results proposed that the SF/nylon 6 nanofibers may be used for biomedical materials such as wound dressing.
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Yeganegi, Masoud. "Characterization of a Biodegradable Electrospun Polyurethane Nanofiber Scaffold Suitable for Annulus Fibrosus Tissue Engineering." Thesis, 2009. http://hdl.handle.net/1807/19004.
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The current study characterizes the mechanical and biodegradation properties of a polycarbonate polyurethane (PU) electrospun nanofiber scaffold intended for use in the growth of a tissue engineered annulus fibrosus (AF) intervertebral disc component. Both the tensile strength and initial modulus of aligned scaffolds were higher than those of random scaffolds and remained unaffected during a 4 week biodegradation study, suggesting a surface-mediated degradation mechanism. The resulting degradation products were non-toxic. Confined compressive mechanical force of 1kPa, was applied at 1Hz to in vitro bovine AF tissue grown on the scaffolds to investigate the influence of mechanical force on AF tissue production, which was found to decrease significantly at 72 hours relative to 24 hours, independent of any effects from mechanical forces. Overall, the consistent rate of PU degradation, along with mechanical properties comparable to those of native AF tissue, and the absence of cytotoxic effects, make this polymer suitable for further investigation for use in tissue-engineering the AF.
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Hsu, Chi-Chuan, and 徐其全. "Preparation and characterization of electrospun silk fibroin/TiO2 naofibers for biomedical applications." Thesis, 2010. http://ndltd.ncl.edu.tw/handle/81814696601350593607.
Full textAbstract:
碩士國立臺灣科技大學
高分子系
98
Using electrospinning to fabricate silk fibroin (SF) nanofiber film was investigated, thus blending different weight ratio of TiO2 with SF solution fabricates SF/TiO2 hybrid nanofibers with optimizative parameters. In this study, we investigated the preparation of nanofibers, and the physical properties, biocompatibility after blending with TiO2 nanoparticle. Scanning electron microscope (SEM) revealed that the SF nanofibers was formed with average diameters 386±73 nm when the concentration of SF was up to 10 %(w/v). The SF/TiO2 nanofibers film was also successfully prepared. FTIR identified the conversion of the random coil (Silk I) conformation of SF into β-sheet (Silk II) by treating with acetone. The maximum photocatalytic decomposition of methylene blue solution was nearly achieved to 50% after 24 hours. Compared with pure SF film, the thermal stability and surface roughness was improved by the blending with TiO2 nanoparticle. The SF/TiO2 nanofibers film provided a better level of equilibrium water content (EWC) and water vapor transmission rate (WVTR) than TegasorbTM (Hydrocolloid dressing). Complete blood count (CBC) and cytotoxicity showed no significantly difference. The SF/TiO2 nanofibers film was found to promote the adhesion, growth and spreading of L929 fibroblasts cells according to a three dimensional network of the nanofibrous structure, and exhibited antibacterial activities against Escherichia coli. In conclusion, the novel nanocomposite mats may be a good candidate as wound dressing for tissue engineering applications.
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Panda, Niladri nath. "Development of electrospun nanofibrous silk fibroin based scaffolds for bone tissue engineering." Thesis, 2014. http://ethesis.nitrkl.ac.in/6573/1/Thesis_Niladri_Nath_Panda.pdf.
Full textAbstract:
The present research focuses on the development of a novel silk fibroin based 3D artificial nanofibrous structure for its usage as a scaffold in bone tissue engineering. Silk fibroin (SF) was extracted from eri and tasar silk cocoons by degumming method and a spinnable SF blend was developed by selection of an optimal binary solvent system i.e. chloroform and formic acid (60:40 w/v). Randomly oriented nanofibrous scaffolds were developed from SF blend by electrospinning. The morphological characteristics of the developed scaffolds were studied by SEM, TEM and AFM. The structural and thermal properties were investigated by XRD, FT-IR, TGA, DSC and TM-DSC. The scaffolds were also characterized for surface property (% water uptake and contact angle measurement) and mechanical property. In vitro cell culture study confirmed the excellent cell supportive property of the scaffold in terms of cell attachment, cell proliferation and cellular metabolic activity using hMSCs derived from umbilical cord blood. The scaffold possessed good osteogenic property as confirmed by ALP, biomineralization, osteocalcein and RUN X 2 expression. All these results suggest that the developed SF blend derived from eri and tasar can be used as a base polymeric scaffold material for tissue engineering application including bone tissue regeneration. Surface property and osteogenic differentiation ability of the nanofibrous SF blend scaffold were further improved by the deposition of nanohydroxyapatite (nHAp) over the surface of the scaffold by surface precipitation method and thus, SF/nHAp composite scaffold was developed. Similar to SF blend scaffold, the composite scaffold was also characterized for surface, mechanical and biological property and the results were compared with that obtained with pure SF blend scaffold. It was demonstrated that the developed composite scaffold showed improved surface property and osteogenic differentiation ability as compared to SF blend as well as the widely used SF scaffold derived from Bombyx mori. Hence, it can be concluded that the developed SF/nHAp nanostructure is a promising scaffold in bone tissue engineering application.