Дисертації з теми "Multi-stimuli response"
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Peng, Tao. "Permeability of responsive polymer-grafted porous membranes, temperature, pH and multi-stimuli response." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 2000. http://www.collectionscanada.ca/obj/s4/f2/dsk1/tape4/PQDD_0020/NQ49832.pdf.
Katsumi, Shiho. "Multi-Stimuli Responsive β-Diketonate Derivatives, from Molecules to Self-Assemblies". Electronic Thesis or Diss., université Paris-Saclay, 2024. http://www.theses.fr/2024UPASF004.
Multi-responsive fluorescent molecules can adjust their fluorescence properties in response to external stimuli such as changes in temperature, pressure, and chemical environment. This adaptability could efficiently direct the development of sensors, displays, and imaging technologies, providing various applications in the future. Mechanofluorochromism (MFC) is a fascinating property in multi-responsive systems, where materials undergo fluorescent changes under mechanical stress like compression, shear force, and friction. Difluoroboron β-diketonate (DFB) compounds draw attention for unique photophysical traits, featuring not only MFC but also polymorphism and intense fluorescence in both solid and solution. This research aims to explore innovative methodologies for designing and synthesizing multi-responsive DFB materials and their precursor compounds. Emphasis is placed on investigating these materials' photophysical characteristics and responsiveness to diverse stimuli. Additionally, the underlying mechanisms of MFC are studied. To achieve these objectives, a comprehensive approach is employed, integrating fluorescence spectroscopy, various microscopic techniques, anisotropic experiments, theoretical calculations, and other relevant methodologies.In the first topic of this thesis, a novel multi-responsive and multicolor DFB is discussed. The synthesis of amino-methoxy-DFB (DFB-NH₂), involving the introduction of a primary amine into the phenyl ring through Curtius rearrangement, was undertaken. Thanks to the NH₂ group, the molecule exhibits intramolecular charge transfer (ICT) in solution and in the crystalline phase. A quinoid-like structure and a typical head-to-tail H-type dimer structure are observed in the crystal state. The single crystal with dark-red weak emission demonstrates a blue-shifted emission after mechanical smearing, which constitutes an original MFC behavior. The drop-casted sample on a paper sheet also demonstrates significant MFC. Additionally, characteristic acid-/base-responsivity is observed in the solution phase, polymer-dispersed films, and powder samples.In the second topic of this thesis, the multi-responsive system is delved into a C₃-symmetrical molecule. A novel C₃-symmetrical β-diketone compound, BTA-D3, and its monomeric counterpart, D, are successfully synthesized. Notably, Aggregation-induced emission (AIE) is observed in BTA-D3 contrary to D. Additionally, BTA-D3 displays polymorph-dependent fluorescence characteristics, forming 1D fibers with yellow emission in the THF/water system, while forming 2D sheets with blue emission. In addition, intramolecular energy transfer properties are demonstrated by BTA-D3, distinguishing it from D.In the third topic of this thesis, energy migration in gel, assembly formations, mechanical effects, and boron complexation of BTA-D3 were explored. Through these experiments, the gelation properties and fluorescence are characterized, revealing their dependence on molecular morphology. Anisotropy analysis in gel offers insights into energy migration within and between molecules, highlighting crucial structures for efficient self-assembly. The unique structure contributes to diverse stimuli-responsive properties, such as chiral induction by chiral solvents and MFC. Notably, boronation of BTA-D3 results in a highly luminescent molecule with a distinctive blue-shift in MFC. These findings contribute to an enriched comprehension of C₃-symmetrical molecules and offer insights into strategies for controlling molecular alignment to achieve diverse fluorescence coloration in molecular materials. The whole thesis seeks to provide practical guidelines and insights for developing new luminescent materials, contributing to advancements in the field with potential applications
Michal, Brian. "Multi-Functional Stimuli-Responsive Polymers." Case Western Reserve University School of Graduate Studies / OhioLINK, 2016. http://rave.ohiolink.edu/etdc/view?acc_num=case1459440396.
Kaufmann, Martin. "Lipid Bilayers Supported by Multi-Stimuli Responsive Polymers." Doctoral thesis, Saechsische Landesbibliothek- Staats- und Universitaetsbibliothek Dresden, 2013. http://nbn-resolving.de/urn:nbn:de:bsz:14-qucosa-106231.
Gernhardt, Marvin. "Multi-material microstructures with novel stimuli-responsive properties." Thesis, Queensland University of Technology, 2021. https://eprints.qut.edu.au/210195/1/Marvin_Gernhardt_Thesis.pdf.
Cresswell, Philip Thomas. "Multi-component stimuli-responsive polymer brushes grafted from flat surfaces." Thesis, University of Bristol, 2013. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.633147.
Cheng, Holden. "Auditory-nerve fiber responses to amplitude modulated tones and multi-tonal stimuli." Thesis, Massachusetts Institute of Technology, 2005. http://hdl.handle.net/1721.1/33844.
Includes bibliographical references (leaves 35-36).
In normal-hearing ears, sound waves are amplified within the cochlea and a small fraction of the sound energy travels backward out into the ear canal, producing sounds known as "otoacoustic emissions" (OAE) that can be measured with a sensitive microphone. One class of OAE, called "stimulus-frequency-otoacoustic-emissions" (SFOAEs), has been hypothesized to be produced by a process known as "coherent reflection filtering" (CRF). The CRF theory provides a prediction between the SFOAE group delay and the group delays of tone responses on the basilar membrane within the cochlea. Using single and multiple-tone stimuli, we collected data from the firing patterns of single auditory-nerve-fibers (ANFs) from which basilar-membrane tone-response group delays can be calculated for both high and low best-frequency (BF) positions along the basilar membrane. These calculated basilar-membrane group delays were compared to published SFOAE group delays. Our results suggest that group delays calculated from the tip, the lower-frequency tail, or the above-BF region of ANF tuning curves do not match the CRF theory prediction. In obtaining the data to the test the CRF theory, we used two methods for obtaining ANF group delays at frequencies above BF: a previously published method and a simpler new method based on the same principle.
(cont.) Surprisingly, the two methods produced different results. Control measurements suggest that the previously published method does not do what it was expected to do.
by Holden Cheng.
S.M.
Nagelberg, Sara(Sara Nicole). "Dynamic and stimuli-responsive multi-phase emulsion droplets for optical components." Thesis, Massachusetts Institute of Technology, 2020. https://hdl.handle.net/1721.1/127708.
Thesis: Ph. D., Massachusetts Institute of Technology, Department of Mechanical Engineering, 2020
Cataloged from student-submitted PDF of thesis.
Includes bibliographical references (pages 136-143).
Dynamic micro-optical components have revolutionized imaging, sensing, and display technologies. Multi-phase emulsions are micro-scale droplets formed from multiple immiscible material components suspended in a fluid medium. An interesting aspect of these droplets is that by tailoring the chemistry of the surrounding medium it is possible to control the droplet morphology or to render the droplets responsive to stimuli in the environment, including light, heat, specific molecules, or even bacteria. This thesis explores the optical characteristics of multi-phase droplets, including their refractive, emissive, and reflective properties. This work focuses predominantly on bi-phase droplets formed from two immiscible oils in water, which form double emulsions or Janus droplets. As tunable refractive components, these droplets form dynamic compound micro-lenses with adjustable focal length that is continuously variable from converging lenses to diverging lenses.
Macroscopically these refractive droplets can appear nearly transparent or strongly scattering, depending on their configurations. When a fluorescent dye is dispersed within the higher refractive index phase, a portion of the light emitted will undergo total internal reflection. This results in a strong morphology-dependent angular emission profile, which can be used in molecular sensing for chemicals or pathogens. In reflection, the droplets produce striking iridescent colors. This is due to the interference light being totally internally reflected at the internal interface along distinct optical paths, leading to color. These optical characteristics are analyzed both experimentally and theoretically. Finite Difference Time Domain simulations were used to model wave-optical effects and phenomena that could be treated using geometrical optics were calculated using a custom-built ray tracing algorithm.
Additionally, a theoretical model was developed to explain the iridescent colors, under a geometric approximation that takes into account interference effects. Experimentally the droplets were characterized using several different custom-built microscope setups. Beyond the optical characteristics, we used these setups to investigate the effects of thermal Marangoni flows within the droplets, which cause the droplets to re-orient towards a heat source. This work sets the foundation of understanding the refractive, reflective, and emissive properties of multi-phase droplets, which could form the basis of dynamically controllable or stimuli-responsive micro-scale optical components.
by Sara Nagelberg.
Ph. D.
Ph.D. Massachusetts Institute of Technology, Department of Mechanical Engineering
Snyder, Savannah R. "PROBING STRUCTURE-PROPERTY RELATIONSHIPS OF STIMULI-RESPONSIVE POLYMERS BY MULTI-DIMENSIONAL MASS SPECTROMETRY." University of Akron / OhioLINK, 2020. http://rave.ohiolink.edu/etdc/view?acc_num=akron1597353164970207.
Zhu, Yanan. "Conception, synthèse et caractérisation d'un nouveau matériau multi-stimuli-responsive à base de spiropyranne." Mémoire, Université de Sherbrooke, 2016. http://hdl.handle.net/11143/8802.
Osypova, Alina. "Design of multi-stimuli responsive films through layer-by-layer assembly for the control of protein adsorption." Thesis, Paris 6, 2015. http://www.theses.fr/2015PA066727.
Protein adsorption on a solid artificial surface is a fundamental phenomenon that determines the biological response of a living organism entering any implant material. Therefore, tailoring surfaces for controlled protein adsorption is at the heart of many of today's research fields including biotechnology and materials science. In this context, stimuli-responsive materials that are able to change their properties as a response to a small change in their physico-chemical environment are attracting a great interest as they allow the creation of surfaces with switchable properties for the control of protein adsorption. In this thesis, we report on the design and elaboration of multi stimuli-responsive thin films and nanotubes. For this purpose, we employed the robust and versatile layer-by-layer (LbL) assembly technique to incorporate block copolymers made of poly(acrylic acid) PAA and poly(N-isopropylacrylamide) PNIPAM with tunable and well-controlled block lengths. The combination of ellipsometry, quartz crystal microbalance with dissipation monitoring (QCM-D), surface plasmon resonance (SPR) and infrared data reveal the possibility to build up (PAH/PAA-b-PNIPAM)n multilayers. The stimuli-responsive properties of these LbL films were examined by monitoring the adsorption of proteins by means of QCM-D and fluorescence measurements, while varying (i) temperature, (ii) pH, (iii) ionic strength, or (iv) a combination of the above parameters. It appears that all these stimuli strongly influence the amount of adsorbed proteins. In short, these new PNIPAM block copolymer-based LbL coatings are easy to build on substrates of various nature and geometry (including nanoporous membranes)
Osypova, Alina. "Design of multi-stimuli responsive films through layer-by-layer assembly for the control of protein adsorption." Electronic Thesis or Diss., Paris 6, 2015. http://www.theses.fr/2015PA066727.
Protein adsorption on a solid artificial surface is a fundamental phenomenon that determines the biological response of a living organism entering any implant material. Therefore, tailoring surfaces for controlled protein adsorption is at the heart of many of today's research fields including biotechnology and materials science. In this context, stimuli-responsive materials that are able to change their properties as a response to a small change in their physico-chemical environment are attracting a great interest as they allow the creation of surfaces with switchable properties for the control of protein adsorption. In this thesis, we report on the design and elaboration of multi stimuli-responsive thin films and nanotubes. For this purpose, we employed the robust and versatile layer-by-layer (LbL) assembly technique to incorporate block copolymers made of poly(acrylic acid) PAA and poly(N-isopropylacrylamide) PNIPAM with tunable and well-controlled block lengths. The combination of ellipsometry, quartz crystal microbalance with dissipation monitoring (QCM-D), surface plasmon resonance (SPR) and infrared data reveal the possibility to build up (PAH/PAA-b-PNIPAM)n multilayers. The stimuli-responsive properties of these LbL films were examined by monitoring the adsorption of proteins by means of QCM-D and fluorescence measurements, while varying (i) temperature, (ii) pH, (iii) ionic strength, or (iv) a combination of the above parameters. It appears that all these stimuli strongly influence the amount of adsorbed proteins. In short, these new PNIPAM block copolymer-based LbL coatings are easy to build on substrates of various nature and geometry (including nanoporous membranes)
Kaufmann, Martin [Verfasser], Carsten [Akademischer Betreuer] Werner, Tilo [Akademischer Betreuer] Pompe, and Marcus [Akademischer Betreuer] Textor. "Lipid Bilayers Supported by Multi-Stimuli Responsive Polymers / Martin Kaufmann. Gutachter: Carsten Werner ; Marcus Textor. Betreuer: Carsten Werner ; Tilo Pompe." Dresden : Saechsische Landesbibliothek- Staats- und Universitaetsbibliothek Dresden, 2013. http://d-nb.info/1068444061/34.
Boularas, Mohamed. "Synthèse de microgels biocompatibles, hybrides et stimulables pour des applications cosmétiques." Thesis, Pau, 2015. http://www.theses.fr/2015PAUU3052/document.
Smart polymer materials can provide wide range of options to induce advanced functional features and relevant surface properties in one material. This all-in-one concept is of great interest for applications that require several simultaneous treatments such as cosmetic application. Herein, we aim to develop oligo(ethylene glycol)-based biocompatible multiresponsive microgels that could both interact on the skin as smart drug delivery system (DDS) while fulfilling advanced properties such as surface protection, mechanical and optical properties. Specifically, aqueous dispersed microgels responsive to pH, temperature and magnetic field were synthesized via multi-step strategy: 1. The synthesis and characterization of pH- and thermo-responsive oligo(ethylene glycol)-based microgels by precipitation polymerization, 2. The encapsulation of pre-formed magnetic nanoparticles via adsorption of the nanoparticles into the multiresponsive microgels. The effect of the microgel microstructure on their pH- and thermo-responsive properties were highlighted thanks to a rational investigation of the crosslink density and acid-functional units distribution within the microgels. Oligo(ethylene glycol)-based microgels with homogeneous distribution of both acid-functional unit and crosslinker allowed the synthesis of highly pH-and thermo-responsive microgels. The hybrid microgels prepared by straightforward encapsulation of pre-formed magnetic nanoparticles were characterized. The homogeneous microstructure of the initial stimuli-responsive biocompatible microgels plays a crucial role for the design of unique well-defined ethylene glycol-based thermoresponsive hybrid microgels. Thus, robust monodisperse thermoresponsive magnetic microgels were produced, exhibiting both a constant value of the swelling-to-collapse transition temperature and good colloidal stability whatever the NPs content. These smart microgels can spontaneously form a transparent film with perfect arrangement of the microgels by simple solvent evaporation process. The characterization of the optical and mechanoelectrical properties of the self-assembled microgel films were performed. We highlighted that the presence of anionic charges inside the microgels emphasizes the mechanoelectrical effect of the films
NARDI, MARTINA. "Synthesis and characterization of novel Methacrylates bearing A 2 (Hydroxymino) Aldehyde group and their copolymers." Doctoral thesis, 2018. http://hdl.handle.net/11573/1344974.
Kaufmann, Martin. "Lipid Bilayers Supported by Multi-Stimuli Responsive Polymers." Doctoral thesis, 2012. https://tud.qucosa.de/id/qucosa%3A26659.
Xiao, Chi-Chong, and 蕭智中. "Photoswitchable and multi chemical stimuli-responsive supramolecular polymer." Thesis, 2017. http://ndltd.ncl.edu.tw/handle/emr42d.
國立交通大學
材料科學與工程學系所
106
In this master thesis, we presented a novel photochromic metallosupramolecular polymer synthesis scheme and properties characterization. The supramolecular polymer self-assembled by metal-ligand coordination and host-guest interactions of pseudorotaxane. The supramolecular polymer was self-assembled by molar ratio = 2:1:1 mixing complex of terpyridine functionalized dibenzo-24-crown-8 (DB24C8) derivatives (5), Zinc ion (Zn2+) and diarylethene-containing ammonium salt (10). Thanks to fluorescence resonance energy transferred from terpyridine to DAE salt, the polymer solution exhibited appreciable emission change either with UV/Vis irradiation or multi-chemical stimulation. The metal-ligand coordination and host-guest interactions can be reversible in the presence of Zn2+/cyclen and base/acid, respectively. Investigations on chemical multi-stimuli response of supramolecular polymer were monitored by UV-Vis, photoluminescence and 1H NMR spectrum. The formation of linear polymer is also evidenced by 1H NMR spectrum and viscosity measurement. This new supramolecular polymer utilized DAE photochromic behavior which changed the metal-terpyridinylmacrocycle fluorescence from deep blue to skyblue, including intensity enhancement and wavelength shift. Meanwhile, we have developed facile photochromic switchable supramolecular polymer that have potential for further applications such as metal, light or pH sensors.
Jordão, Noémi Tamar do Carmo. "Multi Stimuli-responsive Organic Salts: From preparation to functional device application." Doctoral thesis, 2017. http://hdl.handle.net/10362/20453.
蔡孟珈. "Multi Stimuli-Responsive and Controllable Supramolecular polymers Containing Metal-Ligand and Host-Guest Interactions." Thesis, 2016. http://ndltd.ncl.edu.tw/handle/98017631581425928161.
國立交通大學
材料科學與工程學系所
104
A multi-stimuli responsive metallosupramolecular polymer network was constructed by the orthogonal assembly of metal-ligand interaction and conjugated terpyridine functionalized dibnzo-24-crown-8 (DB24C8) host and a tetraphenylethylene derivative as a guest with based aggregation-induced emission (AIE) property is fabricated successfully. Investigations on their AIE behaviors of metallosupramolecular polymer network their corresponding guests by using various glycerol fractions of DMSO and glycerol mixtures. Consecutively, quite different from usual supramolecular polymers constructed before, this novel supramolecular polymer of reversible fluorescence emission are realized by acid-base controllable and reversible supramolecular interactions. This strategy to design supramolecular polymers with switchable AIE property overcomes the common problem of aggregation-caused quenching (ACQ) in usual supramolecular polymers and provides a new concept to develop smart supramolecular polymeric materials.
Arumugaperumal, Reguram, and 艾瑞嵐. "Design and Synthesis of Ratiometric Sensors and Multi-Stimuli Responsive Fluorescence Molecular Switches with Novel BODIPY/Tetraphenylethene (TPE) Functionalized [2]Rotaxane and a Controllable Aggregation Induced Emission Behavior." Thesis, 2022. http://ndltd.ncl.edu.tw/handle/39660963103699833500.
國立交通大學
材料科學與工程學系所
105
The pivotal objective of this dissertation is to design and construct novel fluorescent switchable mechanically interlocked molecular architectures with symmetric stopper and to study their molecular shuttling process under acid-base stimuli control along with their controllable high contrast fluorescence and impressively selective detection of anionic guest species. In the introduction of this doctoral thesis we have described brief early synthetic attempts to create mechanically interlocked molecules (MIMs) such as rotaxanes and catenanes as well as several chemosensing mechanism and aggregation induced emission (AIE). Moreover novel templating methodologies to build MIMs and some latest examples of fluorescence MIMs based molecular shuttles under different control stimuli were also introduced. Indeed, acid-based stimuli can drive the molecular shuttling between the two stations accompanied by changing the AIE behavior of AIE-active mechanically interlocked molecule investigated. Fairly, underplayed chemo sensing mechanisms in these systems were presented. Meanwhile, we have developed facile ratiometric sequential detection of copper and pyrophosphate based on rhodamine appended derivatives in this doctoral thesis as well. In chapter two, a novel multifunctional mechanically interlocked switchable [2]rotaxane R4 containing two molecular stations and rotaxane arms terminated with boron-dipyrromethene (BODIPY) fluorophores and its derivatives were synthesized for the first time by CuAAC click reaction. The shuttling motion of macrocycle between the dibenzylammonium and triazolium recognition sites and the distance dependent photoinduced electron transfer process of R4 is demonstrated by utilizing external chemical stimuli (acid/base). Interestingly, the reversible self-assembly process of R4 was recognized by the acid–base molecular switch strategy. Notably, two symmetrical triazolium groups acted as molecular stations, H2PO4– receptors, and H-bonded donors. Both [2]rotaxane R4 and thread R2 demonstrated excellent optical responses and high selectivity toward H2PO4– ion. The specific motion and guest–host interactions of mechanically interlocked machines (MIMs) were also further explored by quantum mechanical calculations. The thread R2 also demonstrated to enable the detection of H2PO4– in RAW 264.7 cells successfully. In chapter three, a novel near IR fluorescent switchable [2]rotaxane NIR4 composed of two different molecular stations and rotaxane arms terminated with near IR boron-dipyrromethene (BODIPY) fluorophores and its derivatives were synthesized for the first time by CuAAC click chemistry. The molecular shuttling motion could be addressed by the fluorescence signal transduction via distance dependent photo-induced electron transfer process of [2]rotaxane NIR4 triggered by external chemical stimuli (acid/base). The construction and efficient synthesis of [2]rotaxane NIR4 with high level of structural complexity designed always more challenging task of selective anion sensing. Conspicuously, the key to design involved encoding the flexible arms of [2]rotaxane NIR4 triazolium moiety acted as molecular stations and H-bonded donors, which exhibits impressive selectivity and sensitivity toward complementary anionic gust species. The specific mechanical molecular motion of [2]rotaxane NIR4, host-guest interactions of NIR2 and mechanically interlocked molecules (MIMs) were also further explored by quantum mechanical calculations. Importantly, the host of NIR2 and [2]rotaxane NIR4 could be applied for the vivo imaging and clarify the distribution of H2PO4- at subcellular levels. In chapter four, a novel AIE-active switchable [2]rotaxane TR2 incorporating two different molecular stations and rotaxane arms terminated with AIE-active TPE fluorophores and its derivatives were synthesized for the first time by click chemistry. The shuttling behavior of macrocycle component between the two molecular stations can be driven by external acid-base stimuli in solution, accompanied by NMR spectral changes. Investigation of their AIE fluorescence behavior changes showed that these analogous rotaxane are controlled by the molecular motion of the macrocycle component in the presence of external acid-base stimuli. The anion-templated construction of [2]rotaxane TR2 with high level of structural complexity designed always more challenging task. Evidently, the key to design involved encoding the flexible arms of both triazolium motif, is described which exhibit impressive selectivity and sensitivity toward complementary anionic gust species. The specific mechanical molecular motion and host-guest interactions of mechanically interlocked machines (MIMs) were also further explored by quantum mechanical calculations. Importantly, the AIE- active behaviors of [2]rotaxanes TR1, TR2 and TR3 were further investigated to study their potential bio-imaging application and specifically [2]rotaxane TR2 could be applied in vivo imaging with H2PO4- at subcellular levels. In chapter five, two rhodamine hydrazine derivatives Rh1 and Rh2 with catechol and ether functionalities have been synthesized and utilized towards sequential colorimetric detections of Cu(II) and pyrophosphate (PPi) ions in CH3CN–H2O (v/v = 9 : 1, 5 mM Tris–HCl, pH 7.4) semi-aqueous medium. Notably, Rh1 and Rh2 are the first example of colorimetric rhodamine-based probes for the sequential detections of Cu2+ ion and PPi anion. Based on the significant colorimetric responses (from colorless to pink) of Rh1 and Rh2 to Cu2+ ions, the detection limits were estimated as low as 1.22 × 10−8 M and 8.0 × 10−7 M, respectively, which signified the utilities of designed probes towards facile detections of Cu2+ ions. Furthermore, upon the successive addition of PPi ion to Rh1–Cu2+ and Rh2–Cu2+complexes, it has been altered and restored to its origin of Rh1 and Rh2 via re-coordination of PPi to Cu2+ ion, which was confirmed by color changes from pink to colorless. Moreover, computational DFT calculations provided more insights into HOMO–LUMO structures of rhodamine derivatives and their copper complexes. Additionally, the solid state strip-based colorimetric detections of Cu2+ ion were supplemented as a real time application. Thus in conclusion, novel fluorescence mechanically interlocked molecules designed to act as molecular switches have proceeded apace. Delightfully, the molecular shuttling to achieve by the addition of acid-base and studied on AIE behavior indicate that the molecular motion of macrocycle component could induce change the aggregation state of the AIE-active mechanically interlocked molecule. The remarkable stimulated responses towards dihydrogen phosphate (H2PO4-) were discussed. Furthermore, sequential detection of copper and pyrophosphate via ratiometric sensor based on rhodamine derivatives were presented in detail.
Ταπεινός, Χρήστος. "Σύνθεση και χαρακτηρισμός τροποποιημένων πολυλειτουργικών νανοπεριεκτών". Thesis, 2013. http://hdl.handle.net/10889/7889.
The aim of this thesis is the synthesis, characterization and biological evaluation of modified multifunctional nanoparticles (MMNs) as drug delivery systems (DDS, with immediate effect in the treatment of breast and prostate cancer. The term nanoparticles (NPs) refer to the particles which are in the nanometer scale and range in size, from about 1nm to and 100 nm. The term multifunctional refers to the properties of these nanostructures and more particularly to the way that change their properties when external factors such as temperature, pH, redox environment and alternating magnetic field are applied. For the preparation of polymeric nanoparticles, different types of polymerizations were used such as, emulsion polymerization, seed polymerization, atom transfer radical polymerization, dispersion polymerization and polymerization through distillation-precipitation process. The different sensitivities were added via copolymerization of different monomers which exhibit the aforementioned properties. Some of the monomers used like, N-(-2-HydroxyPropyl) Methacrylamide (HPMA), which is sensitive to temperature changes and N,N'-(disulfanediylbis(ethane-2,1-diyl))bis(2-methylacrylamide) (Disulfide) which is sensitive to changes in the redox environment, were synthesized in the laboratory, while the rest, were commercially available. The primary monomer, used in the polymerizations, was Methyl Methacrylate (MMA) which is non-toxic and in through to its polymerization creates spherical structures of certain size (nanospheres). By using the specific monomer, copolymers, which are sensitive to temperature, pH and redox environment or a combination of these factors, were synthesized. The synthesized polymeric nanospheres-nanocontainers, are either hollow inside, or form core-shell structures, where the shell contains the monomers with the desired sensitivity. The cavity which is created inside the nanospheres, in some cases, is intended to entrap pharmaceutical substances. The drug molecules used in this thesis, either within or tethered to the surface of the nanospheres are, Doxorubicin (DOX) and Daunorubicin (DNR). The induction of the magnetic properties in nanocontainers was performed by the synthesis of magnetic nanoparticles (MNPs), prepared on their surface. The use of an alternating magnetic field increases the temperature locally resulting on one hand to facilitate local release of the entrapped drug, and on the other hand, because of the high temperatures developed locally, to lead the tumor cell to apoptosis (programmed cell death). For the characterization of nanoparticles a variety of techniques were used. For the morphological characterization, Scanning Electron Microscopy (SEM) and Transmission Electron Microscopy (TEM) were used while for the structural characterization, Fourier Transform Infrared Spectroscopy (FT-IR), Raman Spectroscopy, Nuclear Magnetic Resonance (NMR) and X-ray diffraction Spectroscopy were used. Magnetic properties were studied by Vibrating Sample Magnetometry (VSM). The Dynamic Light Scattering technique (DLS) was also used in order to get information about the properties and behavior of nanoparticles in solution and Ultra Violet-Visible Spectroscopy (UV-VIS), gave information about Loading and Release of the drugs used in nanocontainers. Hyperthermia measurements were carried out by using an external alternating magnetic field.
Kanaan, Akel Ferreira. "Ionic liquid based functionalized materials for the development of multi-responsive electroactive hydrogels." Doctoral thesis, 2021. http://hdl.handle.net/10316/95400.
The main objective of the present thesis was the development and characterization of novel electroactive ionic liquid-based polycationic hydrogels. These materials were obtained by the functionalization of natural-origin and/or synthetic polymers with an ionic liquid-based vinyl monomer (functionalized at the cation) by two different approaches, namely by the formation of semi-interpenetrating polymer networks (s-IPNs) and by copolymerization with a non-charged comonomer. Through this doctoral work, three different multi-responsive systems were developed targeting a broad range of applications, such as, drug delivery devices, bioseparators, soft actuators, tissue engineering scaffolds, iontophoretic patches and wound dressings. The first approach was employed to obtain multi-responsive s-IPNs hybrid structures based on natural polymers (starch and chitosan) and homopolymers/copolymers of poly(1-butyl-3-vinylimidazolium chloride) (poly(BVImCl) and poly(2-hydroxyethyl methacrylate-co-1-butyl-3-vinylimidazolium chloride) (poly(HEMA-co-BVImCl)). In the case of the starch-based s-IPNs, results demonstrated that the sorption/release capacity of these hydrogels towards L-tryptophan (used as a model biomolecule) could be adjusted depending on the intensity of the applied DC voltage and/or sorption/release medium. It was also confirmed that the process employed to dry the hydrogels (oven and freeze-drying) has a major influence on the conductivity of the materials and that freeze-drying induced higher conductivity values. Furthermore, biological tests demonstrated that the prepared s-IPNs were able to guarantee fibroblasts viability. These newly obtained hybrid materials demonstrated to have potential to be employed for bio-separation processes and for the sustained delivery of specific charged-biomolecules. In the case of the chitosan-based s-IPNs it was demonstrated that the prepared hybrid hydrogels presented enhanced mechanical properties, water swelling capacities (at different pH and ionic strengths) and sorption capacities towards charged molecules when compared to pristine chitosan. Obtained s-IPN hydrogels also demonstrated to have modulated lidocaine hydrochloride permeation/delivery profiles at low current densities (0.56 mA/cm2) and as a function of their charge density. Moreover, biological tests showed that the prepared s-IPN hydrogels were non-hemolytic and presented potential hemostatic capability. These “smart” s-IPNs presented advantageous properties for the design of topical iontophoretic patches and/or hemostatic agents. The second approach was employed to obtain multi-responsive electro-actuating hydrogels based on poly(HEMA-co-BVImCl) copolymers. Studies were performed to evaluate the influence of surface properties on the actuating behavior of the hydrogels in different aqueous media, with different pH and ionic strength values. The different surface properties were obtained by simply employing different mold subtracts, with different hydrophobicities (namely Teflon® and glass) during the copolymer free radical polymerization in aqueous media. Obtained results demonstrated that hydrogels synthesized on Teflon® molds presented the highest electro-actuation capacity in aqueous media, with equivalent bending motion on both directions according to the polarization applied. Moreover, it was also noticed that hydrogels surface charge density and water swelling capacity could be modulated depending on the type of mold utilized during polymerization. Resulting soft stimuli-responsive materials can be regarded as “smart” platforms for the design of soft actuators and cell culture scaffolds for biomedical applications. Overall, this PhD thesis allows concluding that the functionalization of natural and/or synthetic polymers with ILs represents a viable and efficient strategy for the development of multi-responsive electroactive materials for applications in biomedicine, (bio)separation and electrochemistry.
O objetivo principal desta tese foi o desenvolvimento e caracterização de novos hidrogéis eletroativos policatiónicos à base de líquidos iónicos. Esses materiais foram obtidos pela funcionalização de polímeros de origem natural e/ou sintéticos com um monómero vinílico à base de líquidos iónico (funcionalizados no catião) por meio de duas diferentes abordagens, nomeadamente redes poliméricas semi-interpenetradas (s-IPNs) e copolimerização com um comonómero não carregado. Durante a realização do trabalho, foram desenvolvidos três sistemas multi-responsívos diferentes visando uma vasta gama de aplicações, por exemplo, dispositivos para a entrega de fármacos, bioseparadores, atuadores soft, scaffolds para engenharia de tecidos, pensos para iontoforese e para tratamento de feridas. A primeira abordagem consistiu na obtenção de s-IPNs híbridos multi-responsívos à base de polímeros naturais (amido e quitosano) e homopolímeros/copolímeros de poli(cloreto de 1-butil-3-vinilimidazólio) (poli(BVImCl) e poli(metacrilato de 2-hidroxietila-co-cloreto de 1-butil-3-vinilimidazólio) (poli(HEMA-co-BVImCl)). No caso dos hidrogéis s-IPNs à base de amido, os resultados demonstraram que a capacidade de sorção/entrega de L-triptofano, usado como biomolécula modelo, poderia ser otimizada consoante a diferença de potencial aplicada e/ou o tipo de meio utilizado na sorção/libertação. O processo de secagem utilizado nos hidrogéis (secagem em estufa e liofilização), provou ter uma influência significativa na condutividade dos materiais estudados, sendo que os foram sujeitos ao processo de liofilização apresentaram valores superiores de condutividade. Concomitantemente, a viabilidade de fibroblastos na presença dos s-IPNs foi comprovada com recurso a testes biológicos. Desta forma, os materiais híbridos e inovadores desenvolvidos nesta abordagem demonstraram potencial para serem utlizados em processos de biosseparação e para entrega contínua de biomoléculas carregadas específicas. No caso dos s-IPNs à base de quitosano, foi demonstrado que os hidrogéis híbridos desenvolvidos apresentaram melhores propriedades mecânicas, capacidades de entumecimento em água (em diferentes condições de pH e força iónica) e capacidades de sorção para moléculas carregadas, quando comparados com o quitosano puro. Os s-IPNs exibiram perfis modulares de permeação/entrega de lidocaína, a baixas intensidades de corrente (0.56 mA/cm2), em função da respetiva densidade de cargas. Além disso, após testes biológicos, os hidrogéis s-IPN provaram ser não-hemolíticos e hemostáticos. Estes s-IPNs “inteligentes” apresentaram propriedades vantajosas para a preparação de pensos tópicos para iontoforese e/ou pensos hemostáticos. A segunda abordagem estudada foi baseada na obtenção de copolímeros electroactuators híbridos multi-responsívos à base de hidrogéis de poli(HEMA-co-BVImCl). A influência das propriedades de superfícies no comportamento de atuação dos hidrogéis em diferentes meios aquosos (com diferentes valores de pH e força iónica), foi avaliada. Diferentes propriedades de superfície foram obtidas pela simples utilização de diferentes moldes com hidrofobicidade distintas, nomeadamente Teflon® e vidro, durante a copolimerização por polimerização radicalar livre, em meio aquoso. Os resultados demonstraram que os hidrogéis preparados em moldes de Teflon® apresentaram superior capacidade de eletroatuação em meio aquoso, com atuação mecânica equivalente em ambas direções, de acordo com a polaridade aplicada. Para além disso, foi também verificado que a densidade de carga na superfície dos hidrogéis e a capacidade de entumecimento em água pode ser modulada de acordo com o tipo de molde utilizado durante a polimerização. Os materiais responsivos a estímulos podem ser equiparados a plataformas “inteligentes” para a produção de atuadores soft e scaffolds para cultura celular em aplicações biomédicas. Em suma, a presente tese de doutoramento permitiu concluir que a funcionalização de polímeros naturais e/ou sintéticos, com ILs, representa uma estratégia viável e eficiente para o desenvolvimento de materiais eletroativos multi-responsívos para aplicações na biomedicina, biosseparação e eletroquímica.