Dissertations / Theses on the topic 'Nanomaterials - Biomedical Applications'

The field of nanotechnology is growing vastly, both as a field of research and in commercial applications. This rapid growth calls for synthesis methods which can produce high quality nanomaterials, while being scalable. This thesis describes an investigation into the use of a continuous hydrothermal reactor for the synthesis of nanomaterials, with potential use in three different biomedical applications – bone scaffolds, fluorescent biomarkers, and MRI contrast agents. The first chapter of this thesis provides an overview of nanotechnology: the advantages of nanoscale, the commercial industries which can benefit, and the predominant methods currently used to produce nanomaterials. Some advantages and drawbacks of each synthesis route are given, concluding with a description of the Nozzle reactor – the patented technology used for nanomaterial synthesis in this Thesis. Chapter 2 then focusses on the characterisation techniques used in this thesis, detailing the principles of how data is obtained, as well as highlighting the limitations of each method. With the background information in place, chapters 3, 4 and 5 describe more specific nanomaterials and how they can be applied to each of the aforementioned biomedical fields. These chapters provide the technical details of how various nanomaterials can be synthesised using the Nozzle reactor, and the structural data (crystallinity, particle size) obtained from these samples. Furthermore, the functional properties of these nanomaterials are tested and the results, along with a discussion of any trends, are presented. Finally, this thesis concludes with a summary of the results described and emphasises the key areas where further work can be conducted.

Trimetallic nitride endohedral fullerenes (TNT-EMF) have been recognized for their multifunctional capabilities in biomedical applications. Functionalized gadolinium-loaded fullerenes attracted much attention as a potential new nanoplatform for next-generation magnetic resonance imaging (MRI) contrast agents, given their inherent higher 1H relaxivity than most commercial contrast agents. The fullerene cage is an extraordinarily stable species which makes it extremely unlikely to break and release the toxic Gd metal ions into the bioenvironment. In addition, radiolabeled metals could be encapsulated in this robust carbon cage to deliver therapeutic irradiation. In this dissertation, we aim to develop a series of functionalized TNT-EMFs for MRI detection of various pathological conditions, such as brain cancer, chronic osteomyelitis, and gastrointestinal (GI) tract. As a general introduction, Chapter 1 briefly introduces recent progress in developing metallofullerenes for next-generation biomedical applications. Of special interest are MRI contrast agents. Other potential biomedical applications, toxicity, stability and biodistribution of metallofullerenes are also discussed. Finally, the challenges and future outlook of using fullerene in biomedical and diagnosis applications are summarized at the end of this chapter. The large carbon surface area is ideally suited for multiple exo-functionalization approaches to modify the hydrophobic fullerene cage for a more hydrophilic bio-environment. Additionally, peptides and other agents are readily covalently attached to this nanoprobe for targeting applications. Chapter 2 presents the functionalized metallofullerenes conjugated with interleukin-13 peptide exhibits enhanced targeting of U-251 glioblastoma multiforme (GBM) cell lines and can be effectively delivered intravenously in an orthotopic GBM mouse model. Chapter 3 shows, with the specific targeting moiety, the functionalized metallofullerenes can be applied as a non-invasive imaging approach to detect and differentiate chronic post-traumatic osteomyelitis from aseptic inflammation. Fullerene is a powerful antioxidant due to delocalization of the π-electrons over the carbon cage, which can readily react with free radicals and subsequently delivers a cascade of downstream possessions in numerous biomedical applications. Chapter 4 investigates the antioxidative and anti-inflammatory properties of functionalized Gd3N@C80. This nanoplatform would hold great promise as a novel class of theranostic agent in combating oxidative stress and resolving inflammation, given their inherent MRI applications. In chapter 5, Gd3N@C80 is modified with polyethylene glycol (PEG) for working as MRI contrast agents for GI tract. The high molecular weight can prevent any appreciable absorption through the skin or mucosal tissue, and offer considerable advantages for localized agents in the GI tract. Besides the excellent contrast capability, the PEGylated-Gd3N@C80 exhibits outstanding radical scavenging ability, which can potentially eliminate the reactive oxygen species in GI tract. The biodistribution result suggests this nanoplatform can be worked as the potential contrast agent for GI tract at least for 6 hours. A novel amphiphilic Gd3N@C80 derivative is discussed in Chapter 6. It has been noticed for a long time the functionalization Gd3N@C80 contrast agents have higher relaxivity at lower concentrations. The explanation for the concentration dependency is not fully understood. In this work, the amphiphilic Gd3N@C80 derivative is used as the model to investigate the relationship between the relaxivity and concentration of the Gd-based fullerenes. Click chemistry has been extensively used in functionalization due to the high efficiency and technical simplicity of the reaction. Appendix A describes a new type of Sc3N@C80 derivative conducted by employing the click reaction. The structure of Sc3N@C80-alkynyl and Sc3N@C80- alkynyl-benzyl azide are characterized by NMR, MALDI-TOF, UV-Vis, and HPLC. The high yield of the click reaction can provide access to various derivatives which have great potential for application in medical and materials science. The functionalization and characterizations of Ho3N@C80 derivatives are reported in Appendix B. The contrast ability of Ho3N@C80 is directly compared with Gd3N@C80. The Ho-based fullerenes can be performed as the radiotherapeutic agents; the leaching study is performed to test the stability of carbon cage after irradiation. Appendix C briefly shows a new method to develop Gd3N@C80 based targeting platform, which can be used as the probe for chronic post-traumatic osteomyelitis.
PHD

Els amiloides presenten una estructura fibril·lar molt ordenada. Molts d’aquests conjunts de proteïnes apareixen associats a malalties humanes. No obstant això, es pot aprofitar la naturalesa controlable, estable, ajustable i robusta de les fibres amiloides per crear nanomaterials amb una àmplia gamma d’aplicacions. Els prions funcionals constitueixen una classe particular d’amiloides. Aquestes proteïnes transmissibles presenten una arquitectura modular, amb un domini prió desordenat responsable del assemblatge i d’un o més dominis globulars que proporcionen l’activitat. És important destacar que la proteïna globular original es pot substituir per qualsevol proteïna d’interès, sense comprometre el potencial de fibril·lació. Aquestes fusions genètiques formen fibres en les quals el domini global roman plegat, formant nanoestructures funcionals. Tot i això, en molts casos, els impediments estèrics poden restringir l’activitat d’aquestes fibres. Aquesta limitació es pot solucionar disseccionant els dominis priònics en seqüències més curtes que mantenen les seves propietats d’auto-assemblatge alhora que permeten un millor accés a la proteïna en estat fibril·lar. En aquesta tesi doctoral, vam aprofitar el “soft amyloid core” (SAC) del prió de llevat Sup35p com una unitat de muntatge modular, que recapitula la propensió a l’agregació del domini priònic complet. Vam fusionar el SAC amb diferents proteïnes globulars d’interès que difereixen en la conformació i la mida, creant un mètode genètic general i senzill per generar nanofibres dotades de les funcionalitats desitjades. El modelatge computacional ens va permetre conèixer la relació entre la mida dels dominis globulars i la longitud del enllaç que els connecta al SAC, proporcionant les bases per al disseny de nanomaterials amb diferents propietats mesoscòpiques, ja siguin nanofibres o nanopartícules. Sobre aquesta base, hem dissenyat i produït, per primera vegada, nanopartícules amiloides esfèriques altament actives, no tòxiques, de mida definida, i s’han produït nanoestructures bifuncionals amb aplicació en el subministrament específic de fàrmacs. Les lliçons apreses en aquests exercicis van donar lloc a la construcció d’una nanofibrilla similar a un anticòs biespecífic amb potencial per la immunoteràpia. En resum, els nanomaterials funcionals de tipus priònic descrits aquí aprofiten l’enfocament de la fusió genètica per crear un nou conjunt d’estructures amb aplicacions en biomedicina i biotecnologia.
Los amiloides muestran una estructura fibrilar altamente ordenada. Muchos de estos ensamblajes aparecen asociados a enfermedades humanas. No obstante, la naturaleza controlable, estable, modulable y robusta de las fibras amiloides se puede emplear para construir nanomateriales notables con una amplia gama de aplicaciones. Los priones funcionales constituyen una clase particular de amiloides. Estas proteínas transmisibles exhiben una arquitectura modular, con un dominio priónico desordenado responsable del ensamblaje y uno o más dominios globulares que dan cuenta de la actividad. Cabe destacar que la proteína globular original se puede reemplazar con cualquier proteína de interés sin comprometer el potencial de fibrilación. Estas fusiones genéticas forman fibrillas en las que el dominio globular permanece plegado, lo que genera nanoestructuras funcionales. Sin embargo, en muchos casos, el impedimento estérico restringe la actividad de estas fibrillas. Esta limitación puede resolverse diseccionando los dominios de priones en secuencias más cortas que mantengan sus propiedades de autoensamblado mientras permiten un mejor acceso a la proteína en el estado fibrilar. En esta tesis doctoral, exploramos el "soft amyloid core" (SAC) del prion de levadura Sup35p como una unidad modular de autoensamblaje, que recapitula la propensión a la agregación del dominio priónico completo. Fusionamos el SAC con diferentes proteínas globulares de interés que difieren en conformación y tamaños, creando un enfoque genético general y directo para generar nanofibrillas dotadas de las funcionalidades deseadas. El modelado computacional nos permitió obtener información sobre la relación entre el tamaño de los dominios globulares y la longitud del conector que los une con el SAC, proporcionando la base para el diseño de nanomateriales con diferentes propiedades mesoscópicas, ya sean nanofibrillas o nanopartículas. Sobre esta base, diseñamos y producimos, por primera vez, nanopartículas amiloides esféricas, altamente activas, no tóxicas, de tamaño definido, y diseñamos nanoestructuras bifuncionales con aplicación en la administración dirigida de fármacos. Las lecciones aprendidas en estos ejercicios permitieron la construcción de una nanofibrilla similar a un anticuerpo biespecífico con potencial para su uso en inmunoterapia. En resumen, los nanomateriales funcionales similares a los priones descritos aquí aprovechan la metodología de fusión genética para generar un nuevo conjunto de estructuras con aplicación en biomedicina y biotecnología.
Amyloids display a highly ordered fibrillar structure. Many of these assemblies appear associated with human disease. However, the controllable, stable, tunable, and robust nature of amyloid fibrils can be exploited to build up remarkable nanomaterials with a wide range of applications. Functional prions constitute a particular class of amyloids. These transmissible proteins exhibit a modular architecture, with a disordered prion domain responsible for the assembly and one or more globular domains that account for the activity. Importantly, the original globular protein can be replaced with any protein of interest, without compromising the fibrillation potential. These genetic fusions form fibrils in which the globular domain remains folded, rendering functional nanostructures. However, in many cases, steric hindrance restricts the activity of these fibrils. This limitation can be solved by dissecting prion domains into shorter sequences that keep their self-assembling properties while allowing better access to the protein in the fibrillar state. In this PhD thesis, we exploited the "soft amyloid core (SAC)" of the Sup35p yeast prion as a modular self-assembling unit, which recapitulates the aggregation propensity of the complete prion domain. We fused the SAC to different globular proteins of interest differing in conformation and sizes, building up a general and straightforward genetic approach to generate nanofibrils endowed with desired functionalities. Computational modeling allowed us to gain insights into the relationship between the size of the globular domains and the length of the linker that connects them to the SAC, providing the basis for the design of nanomaterials with different mesoscopic properties, either nanofibrils or nanoparticles. On this basis, we designed and produced, for the first time, highly active, non-toxic, spherical amyloid nanoparticles of defined size and engineered bifunctional nanostructures with application in targeted drug delivery. The lessons learned in these exercises resulted in the construction of a bispecific antibody-like nanofibril, showing potential in immunotherapy. In summary, the prion-like functional nanomaterials described here take profit of the genetic fusion approach to render a novel set of structures with application in biomedicine and biotechnology.

Nanomaterial’s properties can be exploited for diagnostic and medical purposes or combined and fine-tuned to obtain multimodal nanoplatforms available for theranostics. For instance, independently from the specific nanomedicine goal, these nanomaterials will immediately contact the organism immune cells, as body’s first defensive barrier. Therefore, a critical step for future translational applications is represented by the assessment of nanomaterial’s impact on the immune system. In this view, the nanoimmunity-by-design concept is the leitmotiv of the Ph.D. project, it consists in the characterization of graphene and other nanomaterials not only from a chemical-physical point of view but also based on the effects that can occur towards the immune system. To pursue this goal, a new experimental model based on human primary immune cell populations, in particular on red blood cells (RBCs) and peripheral blood mononuclear cells (PBMCs) that can be adopted for the immune assessment of a large number of nanomaterials, was developed. To achieve this purpose, the Ph.D. project focused on the immunological characterization of some of the main promising nanomaterials for biomedical applications: carbon nanodots, ultrasmall silica nanoparticles, graphene-oxide-based hydrogels, titanium-based transition metal carbides, and polystyrene nanoparticles, adopting single- cell level techniques (i.e. flow cytometry and single-cell mass cytometry)
Nanomaterial’s properties can be exploited for diagnostic and medical purposes or combined and fine-tuned to obtain multimodal nanoplatforms available for theranostics. For instance, independently from the specific nanomedicine goal, these nanomaterials will immediately contact the organism immune cells, as body’s first defensive barrier. Therefore, a critical step for future translational applications is represented by the assessment of nanomaterial’s impact on the immune system. In this view, the nanoimmunity-by-design concept is the leitmotiv of the Ph.D. project, it consists in the characterization of graphene and other nanomaterials not only from a chemical-physical point of view but also based on the effects that can occur towards the immune system. To pursue this goal, a new experimental model based on human primary immune cell populations, in particular on red blood cells (RBCs) and peripheral blood mononuclear cells (PBMCs) that can be adopted for the immune assessment of a large number of nanomaterials, was developed. To achieve this purpose, the Ph.D. project focused on the immunological characterization of some of the main promising nanomaterials for biomedical applications: carbon nanodots, ultrasmall silica nanoparticles, graphene-oxide-based hydrogels, titanium-based transition metal carbides, and polystyrene nanoparticles, adopting single- cell level techniques (i.e. flow cytometry and single-cell mass cytometry)

New synthetic advances in the control of nanoparticle size and shape along with the development of new surface modifications facilitates the growing use of nanomaterials in biomedical applications. Of particular interest are functional and biocompatible nanomaterials for sensing, imaging, and drug delivery. The goal of this research is to tailor the function of nanomaterials for biomedical applications by improving the biocompatibility of the systems. Our work demonstrates both a bottom up and a post synthetic approach for incorporating stability, stealth, and biocompatibility to metal based nanoparticle systems. Two main nanomaterial projects are the focus of this dissertation. We first investigated the development of a green synthetic procedure to produce gold nanoparticles for biological imaging and sensing. The size and morphology of gold nanoparticles directly impact their optical properties, which are important for their function as imaging agents or their use in sensor systems. In this project, a synthetic route based on the natural process of biomineralization was developed, where a designed protein scaffold initiates the nucleation and subsequent growth of gold ions. To gain insight into controlling the size and morphology of the synthesized nanoparticles, interactions between the gold ions and the protein surface were studied along with the effect of ionic strength on interactions and then subsequent crystal growth. We are able to control the size and morphology of the gold nanoparticles by altering the concentration or identity of protein scaffold, salt, or reducing agent. The second project involves the design and optimization of metal organic framework nanoparticles for an external stimulus triggered drug delivery system. This work demonstrates the advantages of using surface coatings for improved stability and functionalization. We show that the addition of a polyethylene glycol surface coating improved the colloidal stability and biocompatibility of the system. The nanoparticle was shown to successfully encapsulate a variety of small molecule cargo. This is the first report of photo-triggered degradation and subsequent release of the loaded cargo as a mechanism of stimuli-controlled drug delivery. Each of the aforementioned projects demonstrates the design, synthesis, and optimization of metal-based systems for use in biomedical applications.
Ph. D.

Carbon nanomaterials have attracted significant attention in the past decades for their unique properties and potential applications in many areas. This dissertation addresses the preparation, functionalization and potential biomedical applications of various carbonaceous nanomaterials. Trimetallic nitride template endohedral metallofullerenes (TNT-EMFs, M₃N@C₈₀, M = Gd, Lu, etc.) are some of the most promising materials for biomedical applications. Water-soluble Gd₃N@C₈₀ was prepared by the functionalization with poly(ethylene glycol) (PEG) and hydroxyl groups (Gd₃N@C₈₀[DiPEG(OH)ₓ]). The length of the PEG chain was tuned by changing the molecular weight of the PEG from 350 to 5000. The 1H magnetic resonance relaxivities of the materials were studied at 0.35 T, 2.4 T and 9.4 T. Their relaxivities were found to increase as the molecular weight of the PEG decreased, which is attributed to the increasing aggregate size. The aggregate sizes were confirmed by dynamic light scattering. In vivo study suggested that Gd3N@C₈₀[DiPEG(OH)x] was a good candidate for magnetic resonance imaging (MRI) contrast agents. Another facile method was also developed to functinalize Gd₃N@C₈₀ with both carboxyl and hydroxyl groups by reaction with succinic acyl peroxide and sodium hydroxide thereafter. The product was determined to be Gd₃N@C₈₀(OH)~₂₆(CH₂CH₂COOM)~₁₆ (M = Na, H) by X-ray photoelectron spectrometry. The Gd₃N@C₈₀(OH)~₂₆(CH₂CH₂COOM)~₁₆ also exhibited high relaxivity, and aggregates in water. The research on both pegylated and carboxylated Gd₃N@C₈₀ suggests that aggregation and rotational correlation time plays an important role in relaxation, and the relaxivities and aggregation of the water-soluble metallofullerenes can be tuned by varying the molecular weight of the functionality. TNT-EMFs can be encapsulated inside single-walled carbon nanotubes (SWNTs) to form "peapod" structures by heating the mixture of TNT-EMFs and SWNTs in a vacuum. The peapods were characterized by Raman spectrometry and transmission electron microscopy (TEM). The peapods were then functionalized with hydroxyl groups by a high speed vibration milling (HSVM) method in the presence of KOH. The functionalized Gd-doped peapods exhibited high relaxivites and had an additional advantage of "double carbon wall" protection of the toxic Gd atoms from possible leaking. The HSVM method was modified by using succinic acyl peroxide. The modified HSVM method could functionalize multi-walled carbon nanotubes (MWNT) and single-walled carbon nanohorns (SWNHs) with carboxyl groups. In the presence of N-(3-dimethylaminopropyl)-N'-ethylcarbodiimide hydrochloride (EDC), carboxylate MWNTs and SWNHs could be conjugated with CdSe/ZnS quantum dots (QDs). TNT-EMFs were also encapsulated inside SWNHs to form SWNH peapods. SWNH peapods were functionalized by the modified HSVM method and then were conjugated with CdSe/ZnS QDs. The peapods were characterized by TEM. In vitro and in vivo studies indicated that SWNH peapods could serve as a multimodal diagnostic agent: MRI contrast agent (Gd₃N@C₈₀ encapsulated), radio-active therapeutic agent (Lu₃N@C₈₀ encapsulated) and optical imaging agent (QDs).
Ph. D.

Functional polymers are emerging as strong candidates for a variety of biomedical applications, but progress in this field is slow due to the difficulties associated with the synthesis of libraries of polymers. Polymeric scaffolds facilitate the rapid synthesis of such functional polymers by employing click chemistries as a tool for post-polymerisation modification. Acrylic and acetylene based polyhydrazides have been explored as potential scaffolds for the in situ screening of functionalised polymers for biomedical applications. Poly(acryloyl hydrazide) was prepared from commercially available starting materials using RAFT polymerisation in a three step synthesis, and its postpolymerisation modification using a variety of hydrophilic and hydrophobic aldehydes was investigated. Biocompatible solvents and reaction conditions were determined such that the postpolymerisation modification could be achieved with good yields or better. The applicability of the scaffold was shown during the in situ screening of functional polymers for siRNA delivery, which required no isolation or purification of candidate polymers. Poly(4-ethynylbenzohydrazide) was synthesised using rhodium catalysed polymerisation conditions, towards achieving a helical polymer scaffold. Despite the lack of solubility in aqueous solvents, the stability and post-polymerisation modification was analysed in a variety of conditions, opening the possibility of synthesising biodegradable mimics to naturally occurring helical moieties.

Nanotechnology products have huge potential to be a part of the developments in various fields, including functional materials, electronics and medicine. Using nanomaterials in medical applications has been successful for disease diagnosis and drug delivery systems. One of the safest and most versatile nanomaterials utilized for medical purposes are iron oxide nanomaterials. This thesis presents the synthesis, coating and targeting vector modification of iron oxide materials for several biomedical applications including multimodal imaging and cancer cell targeting. Iron oxide nanorods (NRDs) were produced and coated with silica shells as well as other surface modifying molecules including azamacrocycles (DO3A) and polyethylene glycol chains (PEG) which were attached in a one pot reaction. The presence of PEG on the NRDs surface gave improved suspension stability over a wide range of salt concentrations and pH values. Radiolabelling of the NRDs was demonstrated with the positron emitting radioisotope ⁶⁸Ga. The use of nanorods as magnetic resonance imaging (MRI) contrast agents gave a two-fold increase in T2 relaxivity (180 s⁻¹) compared to previous work using spherical nanoparticles. The ⁶⁸Ga labelled NRD constructs show high radiochemical stability against transferrin challenge over a 3 h incubation period. An in vivo bio-distribution study was carried out by intravenously injecting a CD1 nude female mice with 2 mg of (NRDs-PEG), then multimodal imaging analysis was performed using MRI and positron emission tomography (PET) imaging. The NRDs with sizes between 100 to 200 nm showed rapid accumulation in the liver after 5 min due to uptake by macrophages and Kupffer cells as part of reticuloendothelial system, and a small quantity accumulated in the lung and spleen. It was also observed that in the MRI T2 weighted image, the liver is significantly darker than the T1 weighted imaging which confirms the sample accumulation. The multimodal images proved that the radiolabelled NRDs were stable in vivo on the timescale of the imaging study. Iron oxide nanoparticles (IONPs) were functionalised for targeting cancer cells. The IONPs were conjugated to a chemokine receptor targeting vector and the targeting properties were tested in vitro using Jurkat cancer cells with flow cytometry in an antibody competition assay. The NPs showed 100% inhibition of the anti-CXCR4 antibody binding in this assay.

Thesis (Ph. D.)--University of North Carolina at Chapel Hill, 2008.
Title from electronic title page (viewed Dec. 11, 2008). "... in partial fulfillment of the requirements for the degree of Doctor of Philosophy in the Department of Chemistry." Discipline: Chemistry; Department/School: Chemistry.

The biological materials are the versatile scaffolds to fabricate functional nanomaterials. There is an increasing trend of applying the functional nanomaterials in energy applications ranged from conventional sources to renewables. In my early attempts of research, the M13 bacteriophage is used as a versatile bio-scaffold for the fabrication of nanomaterials. In this study, photocatalytically active perovskite strontium titanate (SrTiO3) nanowires are fabricated for the first time using genetically engineered AEEE–M13 phage and metal alkoxide precursors. One newly developed doping approach with an ammonia gas treatment efficiently produced strontium titanate nanowires, which split water and produce hydrogen under visible-light irradiation. The optical absorption of nitrogen doped strontium titanate can be tuned by varying the processing conditions, and lies in the visible spectrum range when treated at 625oC – 650oC. XPS results show that nanowires treated under ammonia flow between 625°C and 650°C have high nitrogen content. The excellent hydrogen evolution rate of these nanomaterials is correlated with both optical absorption and nitrogen doping level. This doping approach is expected to provide a new pathway for the fabrication of other visible-light active photocatalysts including tantalates. Beside to the anodic material, bismuth vanadium oxide (BVO4) nanowires as a cathode is synthesized in a similar method. This material is characterized by XPS, XRD, and TEM to confirm the formation of preferred crystallinity and size. The full reaction of water splitting has been tested by applying both materials and the initial results prove both nanowire materials can sustain for long time without any degradation while maintaining high performances. The electrocatalytic reduction of carbon dioxide by using SrTiO3 and TaON phage template nanowires is unique and innovative approach. Meanwhile, in the research, they have been proven to be more effective than any other bulk catalysts. Controlling the morphology and crystallinity of the electrocatalysts provides the new opportunities to produce various kinds of products including carbon monoxide, formic acid, methanol, ethanol, and methane. In research, we are capable to generate selective products by choosing the catalysts and varying the experimental conditions. Expended from the M13 bacteriophage bio-scaffold, a new biological functional nanomaterial is studied in my second project. DNA is biological ready-made sensor, and it is also small, customizable, and adaptive. The second project aims to develop new tools to improve the process of conventional energy extraction. More specifically, the research focuses to use functional nanomaterials to protect and delivery surfactants during the enhanced oil recovery (EOR). In order to recover hard-to-access oil, surfactants are pumped underground to help release the oil. The delivery area is large and it can take several weeks for the surfactant to reach the oil, which leads to dilution of and loss of the surfactant when it sticks to rocks. In order to improve the oil-to-surfactant yield, a controlled delivery method is of interest. In this project we are developing methods based on biological approaches for delivering surfactants to underground oil fields using nanoparticles that are stable for several weeks under high temperature and high salt conditions. We are using both biomimetic approaches mimicking structures such as diatoms and calcium based algae as well as genetic engineering to build high surfaces area biological sponges to act as surfactants. Motivated from previous project, the same microparticle system encapsulates various kinds of DNA is designed and fabricated for the underground detection to further improve the process of petroleum extraction. Inorganic microparticles containing various DNA segments were designed to be tracers that are used to identify the oilfield’s underground tunnel formations. CaCO3 is designed to encapsulate DNA nanoparticles. In order to prove the existence of DNA inside of particles after the synthesis, confocal imaging is taken on the fluorescence-label DNA particles, and the positive evidences of DNA that is inside of the particles is observed. After releasing the particle by dissolving the shell, the method of PCR is taken to amplify the DNA population and the gel electrophoresis is used to identify the size of DNAs. The same DNA strand that is initially encapsulated into the particle is confirmed as a result. Hence, it proves that the system of nanoparticle encapsulating the DNA is a successful application in the purpose as proposed. Many useful applications derived from the same encapsulation platform are studied and developed. More specifically, various DNA nanostructures are explored and encapsulated in the microparticles. The size control of microparticles is revisited to fulfill specific needs of the different applications. In addition, the particle buoyancy or density is engineered in order to improving the recyclability of the sensors from the aqueous media. The ability of encapsulation is also extended beyond various structures of nucleotide strands. In a few experiments, encapsulations of the gold nanoparticles and upconverting nanoparticles have been proven successfully. These extend the range of applications based on the functional materials inside that enable optical, biological, and environmental functions. Imaging techniques are improved to direct visualize the existence of specific structures. The adoption of typhoon provides a sensitive detection of low concentration of DNA. PAGE gel, compared to agarose gel that is introduced in previous chapter, is used to ensure a better separation among various structured macromolecules and hence a better resolution. DNA nanostructures act as the fundamental sensors responding to pH, ionization, and temperature changes. Learned many valuable insights from previous researches, with proper modifications, we propose new methods of fabricating sensors that allows people to detect the environments that currently no technology can do so.
Engineering and Applied Sciences - Applied Physics

The major topics discussed are all relevant to interfacing brightly phosphorescent and non-luminescent coinage metal complexes of [Ag(I) and Au(I)] with biopolymers and thermoresponsive gels for making hybrid nanomaterials with an explanation on syntheses, characterization and their significance in biomedical fields. Experimental results and ongoing work on determining outreaching consequences of these hybrid nanomaterials for various biomedical applications like cancer therapy, bio-imaging and antibacterial abilities are described. In vitro and in vivo studies have been performed on majority of the discussed hybrid nanomaterials and determined that the cytotoxicity or antibacterial activity are comparatively superior when compared to analogues in literature. Consequential differences are noticed in photoluminescence enhancement from hybrid phosphorescent hydrogels, phosphorescent complex ability to physically crosslink, Au(I) sulfides tendency to form NIR (near-infrared) absorbing AuNPs compared to any similar work in literature. Syntheses of these hybrid nanomaterials has been thoroughly investigated and it is determined that either metallic nanoparticles syntheses or syntheses of phosphorescent hydrogels can be carried in single step without involving any hazardous reducing agents or crosslinkers or stabilizers that are commonly employed during multiple step syntheses protocols for syntheses of similar materials in literature. These astounding results that have been discovered within studies of hybrid nanomaterials are an asset to applications ranging from materials development to health science and will have striking effect on environmental and green chemistry approaches.

The two major topics studied in this dissertation are the gold(I) pyrazolate trimer {[Au(3-R,5-R’)Pz]3} complexes in aqueous chitosan polymer and phosphorescent polymeric nanoparticles based on platinum(II) based complex. The first topic is the synthesis, characterization and optical sensing application of gold(I) pyrazolate trimer complexes within aqueous chitosan polymer. A gold(I) pyrazolate trimer complex, {[Au(3-CH3,5-COOH)Pz]3}, shows high sensitivity and selectivity for silver ions in aqueous media, is discussed for optical sensing and solution-processed organic light emitting diodes (OLEDs) applications. Gold(I) pyrazolate trimer complexes are bright red emissive in polymeric solution and their emission color changes with respect to heavy metal ions, pH and dissolved carbon dioxide. These photophysical properties are very useful for designing the optical sensors. The phosphorescent polymeric nanoparticles are prepared with Pt-POP complex and polyacrylonitrile polymer. These particles show excellent photophysical properties and stable up to >3 years at room temperature. Such nanomaterials have potential applications in biomedical and polymeric OLEDs. The phosphorescent hybrid composites are also prepared with Pt-POP and biocompatible polymers, such as chitosan, poly-l-lysine, BSA, pnipam, and pdadmac. Photoluminescent enhancement of Pt-POP with such polymers is also involved in this study. These hybrid composites are promising materials for biomedical applications such as protein labeling and bioimaging.

There is a growing interest among researchers on the interaction of living systems and biomaterials from the perspective of advanced biomedical engineering applications. Nanomaterials are employed in different biological applications (biosensing, molecular imaging, delivering drug particles, anticancer therapy etc.) because of their noble properties. Recently, boron nitride (BN NP) have attracted significant interest due to its superior chemical, physical and thermal properties and have found practical applications in fields like industrial tool manufacturing, electrical devices, photocatalysis and lubrication. However, studies to assess boron nitride for biomedical applications have been largely limited. This project aims at evaluating BN NP as a potential tool for advanced bioengineering applications. The study is conducted by focusing on four key aspects: nanomaterial characteristics, biocompatibility, uptake process and effect on biophysical properties. Simultaneously, Hydroxyapatite (HAP) was also assessed as a point of reference. Both BN NP and HAP were characterised based on their size, shape, surface charge and porosity to quantify the physical parameters of materials that dictate cellular response to nano-sized materials. The cytotoxicity of BN NP was extensively studied by conducting a number of biological assays. Overall, BN NP was found to be biocompatible within certain concentration range (0-50 μg/ml). Once the biocompatibility of BN NP was established, focus was placed on studying the uptake process and adopted mechanism. Cells were sectioned into thin slides (80 nm) after being cultured with nanomaterials and later imaged using transmission electron microscopy (TEM). Nanomaterials were observed inside cell cytoplasm, which confirmed successful internalisation of BN NP by human cells. The uptake process was extensively studied by analysing the microscopic images in a time dependent manner. The uptake mechanism of both BN NP and HAP was observed to be endocytosis. Finally, the effect of nanomaterial uptake on the biophysical properties of cells was investigated. While assessing nanomaterials, previous studies were largely limited to biological assay. However, in this study, it was hypothesised that, apart from biological consequences, nanomaterials uptake will also affect the physical properties of cells. Robust and accurate experimental techniques were developed to quantify the cell stiffness and adhesion property using Atomic force microscopy (AFM). The obtained results revealed increase in cell stiffness for BN NP treated cells (50 and 100μg/ml) and a significant decrease in adhesion property for HAP treated cells (100μg/ml). Together, these results demonstrated the effect of nanomaterial uptake on biophysical properties of cells and explained the underlying mechanism. This was an innovative way of studying the physical wellbeing of cells, which also contributed in the existing knowledge of nanomaterial toxicity. In summary, BN NP was evaluated in this study through an organised approach considering a number of key aspects. Collectively, this research develops a better understanding of the interaction between BN NP and human cells in in vitro condition and establishes a primary framework for nanomaterial assessment for biomedical use. The results validate BN NP's potential as a suitable biomedical engineering tool and emphasises the need for more research efforts in this field.

Nanotechnologies, defined as the ensemble of disciplines aiming at manipulating matter on an atomic or molecular scale and at exploiting the corresponding properties, have recently emerged as one of the most relevant research fields due to its implications in applied science and technological applications. Nanocrystals (NCs) with a uniformly crystalline structure and at least one dimension in the range 1÷100 nanometers, play a key role as building blocks for the assembly of innovative materials and devices for nanotechnology. A wide variety of nanocrystalline materials showing metallic, semiconducting, magnetic properties or their combinations are now available. It is well documented that nanocrystals exhibit physical properties, ranging from mechanical strength, chemical reactivity and conductivity that depend on their size and structure and differ from those of the corresponding bulk materials. For this reason, nanocrystals are regarded as promising building blocks for the fabrication of functional materials with targeted nanotechnological application. In particular, in semiconducting nanocrystals the formation of a set of discrete energy levels, at which the carriers can exist, results in quantum effects. Size restricts the movements of the charge carriers forcing them into a quantum confinement and is responsible for new properties. Again, magnetic materials with nanometric size may exhibit single domain structures, which reflect in unique physical properties such as superparamagnetism, enhanced coercivity, quantum tunnelling of the magnetization and giant magnetoresistance with respect to multi domain bulk magnets. The controlled manufacture of matter at the nanoscale is considered therefore as a promising route to obtain novel materials which can be exploited in optical, electronic, photovoltaic and magnetic nanotechnological applications. Within this framework, this PhD thesis has been focused on the design, preparation and characterization of heterostructures constituted by nanomaterials of different composition, which could be employed in two relevant areas such as energy and biomedicine. In particular, we have addressed the preparation by chemical solution routes of heterostructures which include different domains (metal-semiconductor and metal-magnet) with the aim to develop nanocrystalline new materials with improved and combined functionalities. A key aspect which has been taken into account is how to control the connection between the domains with different functionalities by tuning appropriate synthetic parameters of high temperature colloidal procedures and how this can be exploited to produce heterostructures with well-controlled morphology and microstructure. In particular, metal-semiconductor heterostructures made out of platinum tips deposited at controlled sites of a chalcogenides semiconductor with a branched octapod morphology were achieved. As the semiconducting domain is able to absorb solar light whereas the noble metal tip is capable to catalyze chemical reactions, it is prospected that the developed materials, i.e. CdSe@CdS-Pt octapods, are active as solar conversion devices and photocatalysis, with particular reference to hydrogen production through optimization of the redox process behind the photocatalytic water splitting reaction. Photophysical investigation of CdSe@CdS-Pt octapods enabled us to point out the effect of heterostructure morphology-properties relationship, as it was found that two regimes for capture of photoexcited electrons by Pt domains take place depending on the location of the metal tips onto the semiconductor octapods. When Pt is deposited at the octapod tip a slow capture takes place after energy relaxation in the semiconductor and result in large spatial separation of charges; while when Pt covers the whole octapods surface an ultrafast capture of hot electrons occurs, and charge separation happens faster than energy relaxation and Auger recombination. As an alternative route to the fabrication of multifunctional nanostructures including different domains, the potential of high temperature polymer-mediated hydrolysis in producing magnetic clusters, which are aggregates constituted of many single crystallite approximately 10 nm in size, has been explored. Such magnetic clusters retain the peculiar properties of the constituent nanoparticles such as superparamagnetism, while exhibiting specific features such as higher magnetization and stability which are advantageous for practical use. Here, the possibility to fine-tune the properties of the clusters by varying the composition of the primary particles has been investigated by including metal nanoparticles (Au, Ag, Pt) and through doping the iron oxide with manganese. This research has been achieved in order to perform a systematic study of the correlation between morpho-structural and magnetic and relaxometric properties, which may be employed for their potential use in biomedical field. The development of novel magnetic doped clusters has enabled to investigate the relaxometric and heat mediator behaviour of the novel materials, in order to evaluate their potential in biomedicine as prospective novel contrast agents for detection through Magnetic Resonance Imaging and as therapeutic tools in Magnetic Fluid Hyperthermia. In addition to contributing to the understanding of the mechanisms behind the preparation of functional and multifunctional heterostructures, this thesis also aims at elucidating the structure-properties relationship at the nanoscale in materials with highly controlled compositional and morphological features. To this end, extensive morphological and structural characterization was carried out by a multi technique approach including in particular X-Ray diffraction, conventional and advanced transmission electron microscopy techniques, X-Ray absorption spectroscopy, UV-visible spectroscopy and dynamic light scattering. The research work is presented according to the following thesis outline: - Chapter 1 deals with a short review on theoretical background, synthetic approaches and physical and chemical properties of semiconductor nanocrystals and magnetic nanocrystals. An overview on application of semiconductor and magnetic nanocrystals in two relevant fields such as energy and biomedicine, respectively, is also provided. - Chapter 2 reports on the design and applications of nanometric metal-semiconductor heterostructures. Here we will discuss in detail the formation of CdSe@CdS-Pt nanocrystal hybrid materials, obtained by synthesizing Pt metal nanoparticles onto preformed CdSe@CdS octapod semiconductor obtained by the seeded growth approach. We will present the physico-chemical properties of the developed heterostructures, as obtained by a systematic structural and morphological characterization. The optical properties of these new materials, performed by ultrafast optical spectroscopy in collaboration with Prof. Michele Saba at the Department of Physics of the University of Cagliari, will also be presented and correlated to the dynamics of charges carriers of the nanocrystals, which can in turn be used to predict their prospective use in photocatalysis. - Chapter 3 describes the synthesis and characterization of magnetic nanoclusters heterostructures based on iron oxide which were in part developed under the supervision of Dr. Antonios Kanaras during a research visit at the University of Southampton (UK). Here, a discussion on the hydrolysis approach adopted in order to produce doped magnetic nanoclusters based on iron oxide, i.e. noble metal M-Fe3O4 (M= Au, Ag, Pt) and MnxFe3-xO4 which may used as heat mediators on hyperthermia treatment cancer and as contrast agents for magnetic resonance imaging is reported. In these samples, the morpho-structural data were correlated to their magnetic and relaxometric behaviour, which was investigated through SQUID magnetometry and diffusion curves in collaboration with Dr. Teresa Pellegrino and coworkers at the Italian Institute of Technology (IIT, Genova). Finally, conclusive remarks and future developments arising from this work are discussed.

Since last century, the rising interest of value-added and advanced functional materials has spurred a ceaseless development in terms of industrial processes and applications. Among the emerging technologies, thanks to their unique features and versatility in terms of supported processes, non-equilibrium plasma discharges appear as a key solvent-free, high-throughput and cost-efficient technique. Nevertheless, applied research studies are needed with the aim of addressing plasma potentialities optimizing devices and processes for future industrial applications. In this framework, the aim of this dissertation is to report on the activities carried out and the results achieved concerning the development and optimization of plasma techniques for nanomaterial synthesis and processing to be applied in the biomedical field. In the first section, the design and investigation of a plasma assisted process for the production of silver (Ag) nanostructured multilayer coatings exhibiting anti-biofilm and anti-clot properties is described. With the aim on enabling in-situ and on-demand deposition of Ag nanoparticles (NPs), the optimization of a continuous in-flight aerosol process for particle synthesis is reported. The stability and promising biological performances of deposited coatings spurred further investigation through in-vitro and in-vivo tests which results are reported and discussed. With the aim of addressing the unanswered questions and tuning NPs functionalities, the second section concerns the study of silver containing droplet conversion in a flow-through plasma reactor. The presented results, obtained combining different analysis techniques, support a formation mechanism based on droplet to particle conversion driven by plasma induced precursor reduction. Finally, the third section deals with the development of a simulative and experimental approach used to investigate the in-situ droplet evaporation inside the plasma discharge addressing the main contributions to liquid evaporation in the perspective of process industrial scale up.

De nos jours, les nanomatériaux inorganiques sont devenus des objets importants pour de nombreuses applications. En même temps la pureté du matériau employé est le facteur clé, et souvent les méthodes de synthèse chimiques ne peuvent assurer l'absence d'une contamination résiduelle. Dans ce contexte, nous avons investigué et développé la synthèse par laser de nanoparticules d'or et de silicium en contrôlant leurs taille et composition. Cette technique se révèle être une approche entièrement physique de la fabrication des nanoparticules pures et exemptes d'agents tensioactifs et de sous-produits toxiques. L'approche engagé comprend deux étapes : 1) la génération de la suspension de micro- et nanoparticules par broyage mécanique, et par ablation préliminaire d'une cible solide ; 2) la fragmentation laser ultra-rapide de colloïdes en suspension qui aboutit à la formation de nanoparticules stables, non agrégées, cristallines et avec une faible dispersion de taille. Ce travail se concentre sur la synthèse de nanoparticules d'or de taille contrôlable entre 7 et 50 nm en absence de ligands. De plus, cette technique nous permet d'obtenir des nano-alliages bimétalliques et d'effectuer un couplage in situ de nanoparticules d'or avec des molécules organiques. Ensuite nous montrons la possibilité d'ajuster la taille moyenne et l'épaisseur de la couche d'oxyde des nanoparticules de Si en variant la concertation des particules initiale, le pH et la quantité d'oxygène dissoutes. Enfin, nous démontrons les propriétés optiques et plasmoniques des nanoparticules obtenues au cours de ce travail et leur potentiel pour les applications catalytiques et biomédicales
Inorganic nanomaterials are of a major interest for numerous applications, specifically bioimaging, biomedicine, catalysis, and also surface enhanced Raman scattering spectroscopy. In most cases, the purity of the employed material is a key factor. Often the conventional chemical ways of synthesis cannot provide the desirable cleanliness. The aim of this thesis is to investigate and develop a laser-based synthetic concept for the fabrication of Au and Si-based nanoparticles with controlled parameters, free of surfactants and toxic by-products. The engaged approach includes two steps: 1) the generation of a raw suspension of micro- and nanoparticles by either mechanical milling or preliminary ablation of a target; 2) ultrafast laser-induced fragmentation from the suspended colloids leading to the formation of stable, non-aggregated, low-size dispersed and crystalline nanoparticles. In particular, we focus on the technique of the synthesis of bare Au nanoparticles with tunable size between 7 and 50 nm in the absence of any ligands. Moreover, this technique allows performing the in situ coupling of the Au nanoparticles with organic molecules and alloying at the nanoscale. Furthermore, we show the possibility of tuning the mean size and the thickness of the oxide shell of Si nanoparticles by varying the initial concentration of microparticles, the pH and the amount of dissolved oxygen. Finally, we demonstrate the optic and plasmonic properties of the nanoparticles synthesized by the techniques established in our work and their potential for the applications in catalysis and biomedicine

As diversas aplicações tecnológicas de nanopartículas magnéticas (NPM) vêm intensificando o interesse por materiais com propriedades magnéticas diferenciadas, como magnetização de saturação (MS) intensificada e comportamento superparamagnético. Embora MNP metálicas de Fe, Co e bimetálicas de FeCo e FePt possuam altos valores de MS, sua baixa estabilidade química dificulta aplicações em escala nanométrica. Neste trabalho foram sintetizadas NPM de Fe, Co, FeCo e FePt com alta estabilidade química e rigoroso controle morfológico. NPM de óxido metálicos (Fe e Co) também foram obtidas. Dois métodos de síntese foram empregados. Usando método baseado em sistemas nanoheterogêneos (sistemas micelares ou de microemulsão inversa), foram sintetizadas NPM de Fe3O4 e Co metálico. Foram empregados surfactantes cátion-substituídos: dodecil sulfato de ferro(III) (FeDS) e dodecil sulfato de cobalto(II) (CoDS). Para a síntese das NPM, foram estudados e determinados a concentração micelar crítica do FeDS em 1-octanol (cmc = 0,90 mmol L-1) e o diagrama de fases pseudoternário para o sistema n-heptano/CoDS/n-butanol/H2O. NPM esferoidais de magnetita com3,4 nm de diâmetro e comportamento quase-paramagnético foram obtidas usando sistemas micelares de FeDS em 1-octanol. Já as NPM de Co obtidas via microemulsão inversa, apesar da larga distribuição de tamanho e baixa MS, são quimicamente estáveis e superparamagnéticas. O segundo método é baseado na decomposição térmica de complexos metálicos, pelo qual foram preparadas NPM esféricas de FePt e de óxidos metálicos (Fe3O4, FeXO1-X, (Co,Fe)XO1-X e CoFe2O4) com morfologia controlada e estabilidade química. O método não mostrou a mesma efetividade na síntese de NPM de FeAg e FeCo: a liga FeAg não foi obtida enquanto que NPM de FeCo com estabilidade química foram obtidas sem controle morfológico. NPM de Fe e FeCo foram preparadas a partir da redução térmica de NPM de Fe3O4 e CoFe2O4, as quais foram previamente recobertas com sílica. A sílica previne a sinterização inter-partículas, além de proporcionar caráter hidrofílico e biocompatibilidade ao material. As amostras reduzidas apresentaram aumento dos valores de MS (entre 21,3 e 163,9%), o qual é diretamente proporcional às dimensões das NPM. O recobrimento com sílica foi realizado via hidrólise de tetraetilortosilicato (TEOS) em sistema de microemulsão inversa. A espessura da camada de sílica foi controlada variando-se o tempo de reação e as concentrações de TEOS e de NPM, sendo então proposto um mecanismo do processo de recobrimento. Algumas amostras receberam um recobrimento adicional de TiO2 na fase anatase, para o qual foi empregado etilenoglicol como solvente e ligante para formação de glicolato de Ti como precursor. A espessura da camada de TiO2 (2-12 nm) é controlada variando as quantidades relativas entre NPM e o precursor de Ti. Ensaios de hipertermia magnética foram realizados para as amostras recobertas com sílica. Ensaios de hipertermia magnéticas mostram grande aumento da taxa de aquecimento das amostras após a redução térmica, mesmo para dispersões diluídas de NPM (0,6 a 4,5 mg mL-1). Taxas de aquecimento entre 0,3 e 3,0oC min-1 e SAR entre 37,2 e 96,3 W g-1. foram obtidos. A atividade fotocatalítica das amostras recobertas foram próximas à da fase anatase pura, com a vantagem de possuir um núcleo magnético que permite a recuperação do catalisador pela simples aplicação de campos magnéticos externos. Os resultados preliminares dos ensaios de hipertermia magnética e fotocatálise indicam um forte potencial dos materiais aqui relatados para aplicações em biomedicina e em fotocatálise.
The most diverse technological applications of magnetic nanoparticles (MNP) have intensifiedthe interest for materials with different magnetic properties such as enhanced saturationmagnetization (MS) and superparamagnetic behavior. Despite the high MS values of metalparticles of Fe, Co, FeCo and FePt, their low chemical stability hinders most applications at thenanoscale. This thesis reports the synthesis of metallic Fe and Co and bimetallic FeCo and FePtMNP with high chemical stability and strict morphological control. MNP of iron oxide and mixediron-cobalt oxide were also synthesized. Two methods were employed. The first method, basedon nanoheterogeneous systems (micellar or reverse microemulsion systems), was used toprepare magnetite and metallic Co NPM. The method applies cation-substituted surfactants:iron(III) dodecyl sulfate iron (FeDS) and cobalt(II) dodecyl sulfate (CoDS). Before the MNPsyntheses, it were studied e determined the critical micelle concentration of FeDS in 1-octanol(cmc = 0.90 mmol L-1) and the pseudo-ternary phase diagram of n-heptane/CoDS/nbutanol/H2O. Spheroidal MNP of magnetite with 3.4 nm in diameter and quasi-paramagneticbehavior were prepared in octanolic FeDS micellar systems. Despite their broad sizedistribution and low MS, metallic Co MNP were produced in reverse microemulsions withchemical stability and superparamagnetic behavior. The second synthesis method, based onthermal decomposition of metal complexes, was employed to prepare spherical FePt and metaloxides (Fe3O4, FeXO1-X, (Co, Fe)XO1-X and CoFe2O4) MNP. Strict morphological control and highchemical stability were reached. Such method does not show the same effectiveness tosynthesize FeAg and FeCo MNP: the FeAg bimetallic alloy was not obtained while FeCo MNPwith chemical stability and compositional control were prepared with no morphological control.Fe and FeCo MNP were produced by thermal reduction of silica-coated Fe3O4 and CoFe2O4 MPN. The coating, beyond to prevent inter-particle sintering, provides biocompatibility andhydrophilic character. The reduced samples showed a significant increase in MS values(between 21.3 and 163.9%), which is directly proportional to MNP size. The silica coating wasaccomplished by tetraethylorthosilicate (TEOS) hydrolysis in reverse microemulsions. Thethickness of the silica layer is controlled by varying the reaction time and concentration of TEOSand NPM. The observations during coating process allowed to propose its probable mechanism.An additional coating of TiO2 (anatase phase) was performed onto silica layer for somesamples. Anatase coating was achieved by using ethylene glycol as both solvent and ligand toproduce an intermediate complex Ti precursor. The variation of the relative amounts of NPMand the Ti precursor allows to control the thickness of the anatase layer between 2 and 12 nm. Assays of magnetic hyperthermia were performed for silica-coated samples. The heating rate of the reduced samples increases after thermal reduction, even for dilute MNP dispersions (0.6 to4.5 mg mL-1). Heating rates between 0.3 and 3.0o C min-1 and SAR in the range of 37.2 96.3 Wg-1 were obtained. The photocatalytic activities of pure anatase particles and TiO2 -coated MNPwere close, but the magnetic samples has the advantage of being recovered from reactionmedia by applying the external magnetic fields. The preliminary results of magnetichyperthermia and photocatalysis assays indicate such materials have strong potential forapplications in biomedicine and photocatalysis.

博士
國立臺灣師範大學
化學系
99
The biomedical applications of nanomaterials in imaging, drug delivery, and therapy have led to ever-growing developments in the past decades. In this work, we combined the second harmonic generation of ZnO nanoparticles and the autofluorescence of the stratum corneum to image the penetration of ZnO nanoparticles under the chemical enhancer conditions of oleic acid, ethanol and oleic acid-ethanol. In addition to qualitative imaging, the microtransport properties of ZnO nanoparticles were quantified to give the enhancements of the vehicle-to-skin partition coefficient, the second harmonic generation intensity gradient and the effective diffusion path length. The results showed that oleic acid, ethanol and oleic acid-ethanol were all capable of enhancing the transdermal delivery of ZnO nanoparticles by increasing the intercellular lipid fluidity or extracting lipids from the stratum corneum. Furthermore, with no additional staining, the two-photon image showed that fluorescent nanoparticles penetrated and resided within interlamellar space of cornea stroma when corneal epithelium barrier was injured. In vitro cytotoxicity test using bovine corneal stromal cells incubated with nanoparticles indicated that the cell viability decreased significantly as the nanoparticles concentration and incubation period increased. Moreover, two-photon imaging showed that nanoparticles can retain within cornea up to 26 days in an in vivo mouse model. On the basis of our in vivo and in vitro data, we conclude that nanoparticles can penetrate and retain within cornea long enough to cause consequential cytotoxicity, under the circumstance that corneal epithelium barrier is injured. In drug delivery applications of nanomaterials, the conjugates of gold nanorods and the model drug, fluorescein isothiocyanate (FITC), embedded inside polyelectrolytes (GNRs/FITC@PLE) were synthesized to study the release kinetics of FITC under femtosecond near-infrared (NIR) laser irradiation. The release of FITC from the conjugates was induced by the heat generated from gold nanorods under laser irradiation. The concentration of released FITC was measured as the time of continuous and periodic laser irradiation was varied. Within 5 min of the laser exposure, the release rates of FITC exhibited zero-order and first-order kinetics under continuous and periodic irradiation, respectively. Furthermore, a drug release system was designed based on the conjugates of gold nanorods and the anticancer drug, paclitaxel (PTX), embedded inside polyelectrolytes (GNRs/PTX@PLE). The release of PTX from the conjugates was triggered by NIR laser irradiation, and the inhibition rates of breast cancer cells showed strong dependencies on the irradiation modes and time.

博士
國立臺灣師範大學
化學系
104
Recent development of molecular imaging probes for fluorescence-guided surgery has shown great progresses for precisely determining tumor margin to execute the tissue resection. Here we synthesize the fluorescent nanoparticles (gold and europium-doped gadolinium oxide) conjugated with nucleolin-targeted AS1411 aptamer. The nanoparticle conjugates exhibit high water-solubility, good biocompatibility, visible fluorescence, strong X-ray attenuation for computed tomography(CT) contrast enhancement and high magnetic susceptibility (europium-doped gadolinium oxide (Gd2O3:Eu) nanoparticles) . The fluorescent nanoparticle conjugates are applied as a molecular contrast agent to reveal the tumor location in CL1-5 tumor-bearing mice by CT imaging. Furthermore, the fluorescence emitting from the conjugates in the CL1-5 tumor can be easily visualized by the naked eyes. After the resection, the IVIS measurements show that the fluorescence signal of the nanoparticle conjugates in the tumor is greatly enhanced in comparison to that in the controlled experiment. The fluorescent imaging clearly reveals that the nanoparticles can be applied as fluorescent tags for cancer-targeting molecular imaging. Our work has shown potential application of functionalized nanoparticles as a multi-function imaging agent in clinical fluorescence-guided surgery. Overall, our results demonstrate that the fluorescence nanoparticles could not only be served as new medical contrast agents but also as intraoperative fluorescent imaging probes for guided surgery in the near future. Nanomaterials not only use on bio-application but also energy storage source, such as lithium battery. For more than a decade, scientists have tried to improve lithium-based batteries by replacing the graphite in one terminal with silicon, which can store 10 times more charge. But after just a few charge / discharge cycles, the I silicon structure would crack and crumble, rendering the battery useless. The new silicon based anodic materials in lithium ion battery (Si-based LIB) are worldwide developed to overcome the capacity decay during the lithiation/delithiation process. In this study, Si nanoparticles coated with 5-sulfoisophthalic acid (SPA) doped polyaniline (core/shell SiNPs@PANi/SPA) composite were prepared and applied as the anodic materials for LIB applications. The detailed structure of core/shell SiNPs@PANi/SPA composite was characterized by high-resolution scanning electron microscopy before and after the charging/discharging. The electrochemical measurements showed that the SiNPs@PANi/SPA anode exhibited high capacity of 925 mAh g-1 and high Columbic efficiency (99.6%) after long-term cyclic life (1000 cycles). Overall results indicated that the SPA dopant doped polyaniline served as a conductive matrix to improve electrical contact and to provide adhesive force in Si-based LIB. Our approach opens a route for the design of efficient silicon nanocomposites for LIB applications. Not only one way we want to approach high performance on anode of battery. We tried different materials like carbon-based metal oxide. Nanostructure composites of lead oxide/copper–carbon (PbO/Cu–C) were synthesized through in situ solvothermal synthesis and heat treatment of PbO/Cu with polyvinylpyrrolidone (PVP) and used as lithium-ion battery anodes. A PbO active particle was embedded in the Cu and PVP–C matrix, accommodating volume changes and maintaining the electronic conductivity of PbO. The composite exhibits superior electrochemical performance, with a capacity of 420 mAh g-1 at a current density of 165 mA g−1, compared with previously reported Pb and PbO composite anodes. The developed anode exhibits >90% capacity retention after 9500 cycles, beginning from the second cycle, at a current density of 5.5 A g−1.

博士
國立成功大學
化學系
103
My research interest is that design the novelty multifunctional nanomaterials, and the unique properties materials were discovered by instrument. In the application, the nanomaterials had great potential to be used in the biomedical field. The multifunctional hybrid nanomaterials be provided with special structure and diversity properties (optical, magnetic and catalytic activity, etc.), and even can be used to load intolerable in water or relative instability drug or agent, and the use of characteristics of the material to drive the controlled release of drugs. My research has developed three multifunctional hybrid nanomaterials, each material has its own peculiarities and application, and it will be divided into three topics for discussed in detail. In the first research topic (Chapter2), the thermally induced cross-linked esterification occurs for the formation of eccentric inorganic-polymeric nanoparticles. By taking advantage of eccentricity, Ag-PSMA eccentric structure is converted to raspberry-like Au-based Janus nanoparticles. In the second research topic (Chapter3), a new multifunctional nanoparticle to perform a near-infrared (NIR)-responsive remote control drug release behavior was designed for applications in the biomedical field. Different from the previous studies in formation of Fe3O4-Au core-shell nanoparticles resulting in a spherical morphology, the heterostructure with polyhedral core and shell was presented with the truncated octahedral Fe3O4 nanoparticle as the core over a layer of trisoctahedral Au shell. The strategy of Fe3O4@polymer@Au was adopted using poly-L-lysine as the mediate layer, followed by the subsequent seeded growth of Au nanoparticles to form a Au trisoctahedral shell. Fe3O4@Au trisoctahedra possess high-index facets of {441}. To combine photothermal and chemotherapy in a remote-control manner, the trisoctahedral core-shell Fe3O4@Au nanoparticles were further covered with a mesoporous silica shell, yielding Fe3O4@Au@mSiO2. The bondable oligonucleotides (referred as dsDNA) were used as pore blockers of the silica shell that allowed the controlled release, resulting in a NIR-responsive DNA-gated Fe3O4@Au@mSiO2 nanocarrier. Taking advantage of the magnetism, remotely triggered drug release was facilitated by magnetic attraction accompanied by the introduction of NIR radiation. DNA-gated Fe3O4@Au@mSiO2 serves as a drug control and release carrier that features functions of magnetic target, MRI diagnosis, and combination therapy. The results verified the significant therapeutic effects on tumors with the assistance of combination therapy consisting of magnetic guidance and remote NIR control. In the third research topic (Chapter4), Since its discovery in 1894, the Fenton reaction, Fe2+ + H2O2 → Fe3+ + •OH + OH−, has been used to treat wastewater and contaminated soil and oxidize organic pollutants. Apart from the reactive oxygen species (ROS) manipulation strategies known as chemotherapy, radiotherapy, and phototherapy, the merge of nanotechnology with old chemistry without electromagnetic waves and O2 creates an appealing exogenous and controllable ROS-generating platform to produce ROS that acts against cancer cells. Hydrogen peroxide-encapsulated Fe3O4-embedded poly(lactic-co-glycolic acid) polymersomes produce ROS at a temperature as low as 39 °C, the temperature a human body can withstand for killing cancer cells.

New derivatives of carbon nanostructures: nanotubes, nano-onions and nanocrystalline diamonds were obtained through fluorination and subsequent functionalization with sucrose. Chemically modified nanocarbons show high solubility in water, ethanol, DMF and can be used as biomaterials for medical applications. It was demonstrated that sucrose functionalized nanostructures can find applications in nanocomposites due to improved dispersion enabled by polyol functional groups. Additionally, pristine and chemically derivatized carbon nanotubes were studied as nanofillers in epoxy composites. Carbon nanotubes tailored with amino functionalities demonstrated better dispersion and crosslinking with epoxy polymer yielding improved tensile strength and elastic properties of nanocomposites.

Yes
In 1985, the serendipitous discovery of fullerene triggered the research of carbon structures into the world of symmetric nanomaterials. Consequently, Robert F. Curl, Harold W. Kroto and Richard E. Smalley were awarded the Noble prize in chemistry for their discovery of the buckminsterfullerene (C60 with a cage-like fused-ring structure). Fullerene, as the first symmetric nanostructure in carbon nanomaterials family, opened up new perspectives in nanomaterials field leading to discovery and research on other symmetric carbon nanomaterials like carbon nanotubes and two-dimensional graphene which put fullerenes in the shade, while fullerene as the most symmetrical molecule in the world with incredible properties deserves more attention in nanomaterials studies. Buckyball with its unique structure consisting of sp2 carbons which form a high symmetric cage with different sizes (C60, C70 and so on); however, the most abundant among them is C60 which possesses 60 carbon atoms. The combination of unique properties of this molecule extends its applications in divergent areas of science, especially those related to biomedical engineering. This review aims to be a comprehensive review with a broad interest to the biomedical engineering community, being a substantial overview of the most recent advances on fullerenes in biomedical applications that have not been exhaustively and critically reviewed in the past few years.

Yes
Electrospinning is a versatile technique that has gained popularity for various biomedical applications in recent years. Electrospinning is being used for fabricating nanofibers for various biomedical and dental applications such as tooth regeneration, wound healing and prevention of dental caries. Electrospun materials have the benefits of unique properties for instance, high surface area to volume ratio, enhanced cellular interactions, protein absorption to facilitate binding sites for cell receptors. Extensive research has been conducted to explore the potential of electrospun nanofibers for repair and regeneration of various dental and oral tissues including dental pulp, dentin, periodontal tissues, oral mucosa and skeletal tissues. However, there are a few limitations of electrospinning hindering the progress of these materials to practical or clinical applications. In terms of biomaterials aspects, the better understanding of controlled fabrication, properties and functioning of electrospun materials is required to overcome the limitations. More in vivo studies are definitely required to evaluate the biocompatibility of electrospun scaffolds. Furthermore, mechanical properties of such scaffolds should be enhanced so that they resist mechanical stresses during tissue regeneration applications. The objective of this article is to review the current progress of electrospun nanofibers for biomedical and dental applications. In addition, various aspects of electrospun materials in relation to potential dental applications have been discussed.

博士
國立臺灣大學
化學研究所
96
In this research, we explored the bio-applications of mesoporous silica nanomaterials for bio-imaging and targeted drug delivery. Mesoporous silica nanoparticles (MSNs) with positive surface charge incorporated with Gd(DTPA) by electrostatic force show the high r1 and r2 relaxivity, which are much higher than those of free Gd(DTPA). These composite nanomaterials show the slower excretion rate from animal body and could be a potential blood-pool MRI contrast agent for angiography. For cellular imaging and effective cell therapy, we also successfully synthesized two types of multifunctional MSNs nanoprobes with fluorescence and paramagnetism. Both nanomaterials show high sensitivity to MRI, good photo-stability, high cell labeling efficiency and low cytotoxicity. The nanoprobes labeled cells could be clearly visualized by MRI and optical modalities. In the last part, green fluorescence MSNs were modified with monoclonal antibody, Herceptin, to target the Her2/neu over-expressing breast cancer cell. MSNs with highest density of Herceptin on the outer surface show the highest selectivity to the targeted cell and the further modification with polyethylene glycol (PEG) can prevent from the non-specific targeting for the MSNs with low density of Herceptin. We also used the confocal microscope and TEM to demonstrate the Herceptin functionalized MSNs could be engulfed by Her2/neu positive breast cancer cells through the receptor-mediated endocytosis.

博士
國立中山大學
海洋生物科技博士學位學程
104
This thesis presents the exploration of nanoparticles in the use of biological application. Here in this work various nanoparticles are employed like Graphene oxide and Gold nanorods use for photothermal therapy. Carbon dots use as a matrix and drug delivery vehicle. Graphene oxide (GO) is a close derivative of graphene has unlocked many pivotal steps in drug delivery due to their inherent biocompatibility, excellent drug loading capacity, antibacterial, antifungal and high water solubility. we have conjugated them with gold nanorods (GNRs) using in situ synthesis of GO@GNRs via seed mediated method. To the above conjugate, Doxorubicin (DOX) was attached at ambient temperature (28±2°C). The enhancement in NIR induced drug release and photothermal property was observed which indicates that the fGO@GNRs-DOX method is an ideal choice for chemotherapy and photothermal therapy simultaneously. Delivery of therapeutic moieties using water soluble Carbon dots (C-dots) has been pivotal to control the release of the drugs under physiological condition due to their high biocompatibility. Controlled Dopamine hydrochloride (DA), a potential neurotransmitter using C-dots as carriers is studied in the present work, in order to highlight its potential to deliver drugs related with neurological disorders such as Alzheimer’s and Parkinson’s disease. In order to understand the impact of the C-dots-DA conjugate under physiological conditions, Nero 2A cells were taken under consideration. Photothermal treatment of graphene oxide (GO) for antibacterial, antifungal and controlling the wound infection treatment using near infrared laser Nd-YAG (1064 nm) were reported. Various pathogenic bacteria (Pseudomonas aeruginosa, Staphylococcus aureus) and fungal (Saccharomyces cerevisiae and Candida Utilis) were investigated. The Cytotoxicity was measured using the proteomic analysis, optical density (OD600), standard micro dilution procedures, TEM and Epifluorescence microscopy. The laser mediated surface activation of GO was achieved for efficient antifungal and antibacterial therapeutic strategy. GO provided unassailable effects and wide applicability. Wound infection treatment is one of the most challenging problems to be addressed in infectiously microbiological treatment. This is mainly due to the pathogen’s ability for fast mutation and generating severely antibiotic resistance to antimicrobial treatment. Therefore, we have proposed a novel method by using gold nanorods (Au NRs) to assist the Nd-YAG laser (1064 nm) for photothermal killing pathogenic bacteria (Pseudomonas aeruginosa) for directly healing the wound infection on the (albino) mice. The current approach can be used to control severe skin infections from antibiotic resistant pathogens in wounds. Carbon dots (C-dots) exhibit strong absorbance in the UV (220-350nm) range, which was exploited to transfer the energy from N2 laser (337 nm) of Matrix-assisted laser desorption/ionization-Mass Spectroscopy (MALDI-MS) to analytes for their rapid detection. Due to this strong feature and extremely small size (2- 4 nm), they were used to enhance the signal intensity of MALDI-MS peaks of low molecular weight biomarkers in serum. In this study, we utilized the extraordinary property of C-dots as a matrix for the detection of Serotonin (Sr), Glutamic Acid (GA) and Dopamine Hydrochloride (DA) by using MALDI-MS.

New derivatives of carbon nanostructures: nanotubes, nano-onions and nanocrystalline diamonds were obtained through fluorination and subsequent functionalization with sucrose. Chemically modified nanocarbons show high solubility in water, ethanol, DMF and can be used as biomaterials for medical applications. It was demonstrated that sucrose functionalized nanostructures can find applications in nanocomposites due to improved dispersion enabled by polyol functional groups. Additionally, pristine and chemically derivatized carbon nanotubes were studied as nanofillers in epoxy composites. Carbon nanotubes tailored with amino functionalities demonstrated better dispersion and crosslinking with epoxy polymer yielding improved tensile strength and elastic properties of nanocomposites. Reductive functionalization of nanocarbons, also known as Billups reaction, is a powerful method to yield nanomaterials with high degree of surface functionalization. In this method, nanocarbon salts prepared by treatment with lithium or sodium in liquid ammonia react readily with alkyl and aryl halides as well as bromo carboxylic acids. Functionalized materials are soluble in various organic or aqueous solvents. Water soluble nanodiamond derivatives were also synthesized by reductive functionalization of annealed nanodiamonds. Nanodiamond heat pretreatment was necessary to yield surface graphene layers and facilitate electron transfer from reducing agent to the surface of nanoparticles. Other carbon materials such as activated carbon and anthracite coal were also derivatized using reductive functionalization to yield water soluble activated carbon and partially soluble in organic solvents anthracite. It was shown that activated carbon can be effectively functionalized by Billups method. New derivatives of activated carbon can improve water treatment targeting specific impurities and bio active contaminants. It was demonstrated that functionalized carbon nanotubes are suitable for real time radiation measurements. Radiation sensor incorporating derivatized carbon nanotubes is lightweight and reusable. In summary, functionalization of carbon nanomaterials opens new avenues for processing and applications ranging from biomedicine to radiation sensing in space.

**English** Plasmonic particles such as gold nanorods (GNRs) are showing themselves as powerful contrast agents for important applications such as photoacoustic imaging and photothermal ablation of cancer. However, their unique photothermal conversion efficiency can turn into a practical disadvantage, and expose them to the risk of overheating and irreversible photodamage. The processes of prefusion and remodeling of GNRs under illumination with optical pulses of typical duration of the order of a few ns will be studied in depth. A retrospective classification of these approaches will be undertaken according to often implicit principles, such as: constraining the initial shape, speeding up their thermal coupling with the environment by lowering their thermal resistance at the interface, or redistributing the incoming energy among several particles. Advantages and disadvantages and contexts of practical interest in which one solution may be more appropriate than the other will be discussed. Stabilization of the optical properties of anisotropic plasmonic particles by thermal heating and laser irradiation is an important issue in many biomedical applications. The effect that small thiols have on the thermal photostability of gold nanorods will be addressed. The nanoparticles were treated with mixtures of poly-ethylene-glycol thiolate (PEG-SH) and methyl-benzene-thiol (MBT) with molar ratios ranging from 0 (for the case of pure PEG) to 20, and then incubated in an oven. under sub-boiling conditions. Small thiols have been found to greatly improve the thermal stability of GNRs. For example, after 1 hour at 90 °C the samples with pure PEG lost more than 70% of the optical absorbance in their initial peak position, while the particles covered with a dense layer of MBT remained almost unchanged. It is possible to attribute this effect to a modulation of the activation barrier for the superficial diffusion of the gold atoms. Furthermore, we addressed the translation of this effect on the photostability of irradiated gold nanorods under conditions of interest for photoacoustic imaging and it was found that small thiols delay the damage thresholds by up to a factor of 2. In this work of thesis also describes the effect of the thermal resistance at the gold-water interface (Kapitza resistance) on the photoacoustic conversion performance of gold nanorods. The results indicate possible strategies for optimizing plasmonic particles as contrast agents for imaging, or even as transducers for biosensors. An effective approach is also suggested to modulate the Kapitza resistance by including features not yet well studied such as roughness or the presence of adsorbates. Following this idea, a rough variant of gold nanorods was synthesized by galvanic deposition and replacement of a silver shell, where roughness provides photoacoustic signals approximately 70% higher and damage thresholds of 120%. Furthermore, the particles were coated with a protein crown, which brings about a decrease in photoacoustic signals as the thickness of the shell increases; this could inspire new solutions for biosensors based on a photoacoustic transduction mechanism. Both of these results are consistent with effective modulation of Kapitza resistance, which can decrease with roughening, due to an increase in specific surface area, and can increase with the introduction of a protein coating (which can act as insulation thermal). Hybrid materials consisting of core/shell Au/Ag nanorods have also been developed, included in porous biomimetic phantoms (scaffolds) of chitosan/polyvinyl alcohol (chitosan/PVA) for applications in tissue engineering and wound healing. The combination of Au and Ag in a single construct provides synergistic opportunities for optical activation of functions such as near-infrared laser tissue welding and remote interrogation for the acquisition of prognostically relevant parameters in monitoring wound healing. In particular, the bimetallic component ensures improved optical tunability, shelf life and photothermal stability, acts as a reservoir for germicidal silver cations. At the same time, the polymer blend is ideal for bonding to connective tissue following photothermal activation and for supporting manufacturing processes that provide high porosity, such as electro-spinning, thus setting all the conditions for cell repopulation and antimicrobial protection. In summary, in this work, the optimization of an important system such as GNRs for complementary applications in different biomedical fields has been addressed; their stability and photoacoustic conversion efficiency have been optimized for use as contrast agents optical, developing functional coatings with small organic molecules or with metal porous layers. Finally, the integration of Au/Ag bimetallic nanorods into hybrid scaffolds for tissue engineering was evaluated, exploiting both the photothermal conversion efficiency and the optical sensitivity to oxidative stress conditions, in order to activate processes and monitor parameters of interest in scope of wound healing. **Italiano** Le particelle plasmoniche come i nanorods d'oro (GNRs) si stanno mostrando potenti agenti di contrasto per applicazioni importanti come l'imaging fotoacustico e l'ablazione fototermica del cancro. Però, la loro efficienza unica di conversione fototermica può trasformarsi in uno svantaggio pratico, e esporli al rischio di surriscaldamento e fotodanneggiamento irreversibile. Verranno approfonditi i processi di prefusione e rimodellazione dei GNRs sotto illuminazione con impulsi ottici di durata tipica dell'ordine di pochi ns. Verrà intrapresa una classificazione retrospettiva di tali approcci secondo principi spesso impliciti, come: vincolare la forma iniziale, velocizzare il loro accoppiamento termico con l'ambiente abbassando la loro resistenza termica all'interfaccia, oppure ridistribuire l'energia in ingresso tra più particelle. Saranno discussi vantaggi e svantaggi e contesti di interesse pratico in cui una soluzione può essere più appropriata dell'altra. La stabilizzazione delle proprietà ottiche delle particelle plasmoniche anisotrope tramite riscaldamento termico e irradiazione laser è una questione importante in molte applicazioni biomediche. Verrà affrontato l'effetto che piccoli tioli hanno sulla fotostabilità termica dei nanorods d'oro. Le nanoparticelle sono state trattate con miscele di poli-etilen-glicole tiolato (PEG-SH) e metil-benzen-tiolo (MBT) con rapporti molari compresi tra 0 (per il caso del PEG puro) e 20, e poi incubati in stufa in condizioni di sub-ebollizione. È stato scoperto che i piccoli tioli migliorano notevolmente la stabilità termica dei GNRs. Ad esempio, dopo 1 ora a 90 °C i campioni con PEG puro hanno perso più del 70% dell'assorbanza ottica nella loro posizione di picco iniziale, mentre le particelle ricoperte di un denso strato di MBT sono rimaste pressoché invariate. È possibile attribuire questo effetto ad una modulazione della barriera di attivazione per la diffusione superficiale degli atomi d'oro. Inoltre, abbiamo affrontato la traduzione di questo effetto sulla fotostabilità dei nanorods d'oro irradiati in condizioni di interesse per l'imaging fotoacustico ed è stato scoperto che i piccoli tioli ritardano le soglie di danneggiamento fino a un fattore di 2. In questo lavoro di tesi viene descritto inoltre l'effetto della resistenza termica all'interfaccia oro-acqua (resistenza di Kapitza) sulle prestazioni di conversione fotoacustica dei nanorods d'oro. I risultati indicano possibili strategie per l'ottimizzazione delle particelle plasmoniche come agenti di contrasto per l'imaging, o anche come trasduttori per i biosensori. Viene inoltre suggerito un approccio efficace per modulare la resistenza di Kapitza includendo caratteristiche ancora non ben studiate come rugosità o presenza di adsorbati. Seguendo questa idea è stata sintetizzata una variante rugosa di nanorods d'oro per deposizione e sostituzione galvanica di un guscio d'argento, dove la rugosità fornisce segnali fotoacustici più elevati di circa il 70% e soglie di danneggiamento del 120%. Inoltre, le particelle sono state rivestite con una corona proteica, la quale apporta una diminuzione dei segnali fotoacustici con l'aumentare dello spessore del guscio; questo potrebbe ispirare nuove soluzioni per biosensori basate su un meccanismo di trasduzione fotoacustica. Entrambi questi risultati sono coerenti con un'efficace modulazione della resistenza di Kapitza, che può diminuire con l'irruvidimento, a causa di un aumento della superficie specifica, e può aumentare con l'introduzione di un rivestimento proteico (il quale può fungere da isolamento termico). Sono stati anche sviluppati materiali ibridi costituiti da nanorods core/shell Au/Ag, inclusi in fantocci biomimetici (scaffold) porosi di chitosano/polivinilil alcol (chitosano/PVA) per applicazioni nell'ingegneria tissutale e nella guarigione delle ferite (wound healing). La combinazione di Au e Ag in un unico costrutto fornisce opportunità sinergiche per l'attivazione ottica di funzioni come la saldatura dei tessuti con laser nel vicino infrarosso e l’interrogazione remota per l’acquisizione di parametri di rilevanza prognostica nel monitoraggio della guarigione delle ferite. In particolare, la componente bimetallica assicura sintonizzabilità ottica, durata di conservazione e stabilità fototermica migliori, funge da serbatoio di cationi d'argento germicidi. Allo stesso tempo, la miscela polimerica è ideale per essere legata al tessuto connettivo a seguito di attivazione fototermica e per supportare i processi di fabbricazione che forniscono un’elevata porosità, come l'elettrofilatura, ponendo così tutte le premesse per il ripopolamento cellulare e la protezione antimicrobica. In sintesi, in questo lavoro, è stata affrontata l'ottimizzazione di un sistema importante come i GNRs per applicazioni complementari in diversi ambiti biomedici; ne è stata ottimizzata la stabilità e l'efficienza di conversione fotoacustica per essere utilizzati come agenti di contrasto ottico, sviluppandone rivestimenti funzionali con piccole molecole organiche oppure con strati porosi metallici. Infine è stata valutata l'integrazione di nanorods bimetallici di Au/Ag in scaffold ibridi per ingegneria tissutale, sfruttandone sia l'efficienza di conversione fototermica sia la sensibilità ottica alle condizioni di stress ossidativo, allo scopo di attivare processi e monitorare parametri di interesse nell'ambito del wound healing.

Mestrado em Engenharia Química
Nanoscience has recently experienced a strong development, Magnetic Nanoparticles (MNPs) are one of the most attractive nanomaterials. Focusing on the biomedical applications, this thesis has as main objective the development of new carbon coating methods in order to reach the maximum biocompatibility of MNPs upon synthesis. During the research carried out, two different approaches were evaluated to coat a magnetic core composed of magnetite, using phloroglucinol and glyoxal, following the idea of making the process more sustainable and biocompatible. The difference between those approaches resides on the use of PF-127 as porogen agent during the coating step. However, some significant differences were found for the material synthesized without PF-127 as porogen agent, with the most important one being the lack of stabilization in water, a crucial characteristic of MNPs for biomedical applications. This mishap leaded to the continuation of the methodology development with just one material. The material selected was evaluated as nanocarrier to load and deliver drugs using doxorubicin (DOX) and omeprazole (OME). The delivery was tested at different pH values in order to evaluate its influence, as human body has different pH in a normal tissue (pH 7.4) than in the intracellular tumor environment (pH 4.5) or in its surroundings (pH 6.0).
A nanociência tem experimentado recentemente um forte desenvolvimento. As nanopartículas magnéticas (MNPs) têm sido um dos materiais mais atraentes. Com foco nas aplicações biomédicas, esta tese tem como objetivo principal desenvolver novos métodos de revestimento de carbono para alcançar a máxima biocompatibilidade durante a síntese de MNPs. Durante a pesquisa serão avaliadas duas abordagens diferentes para revestir um núcleo magnético feito de magnetita, as duas utilizan floroglucinol e glioxal, seguindo a ideia de tornar o processo mais sustentável e biocompatível. A diferença entre essas abordagens será sobre o emprego da PF-127 como agente porógeno durante a etapa de revestimento. No entanto, algumas diferenças significativas foram encontradas que o material sintetizado sem a PF-127 como agente porógeno não estava arquivando uma das características mais importantes das MNPs para aplicações biomédicas, a estabilização na água. Este mishap conduziu a continuar a metodologia apenas com um material. O material selecionado foi avaliado para carga e entrega de medicamentos com doxorrubicina e omeprazol. A entrega foi testada em diferentes valores de pH para avaliar sua influência, pois o corpo humano tem pH diferente em um tecido normal (pH 7,4) do que no ambiente tumoral intracelular (pH 4,5) ou em seu entorno (pH 6,0).

The aim of this thesis is to investigate the property of some typical photovoltaic and luminescent materials, and the possible application of these materials in the fields of solar energy, light emitting diode and biomedical imaging. Earth abundant and nontoxic material quaternary semiconductor copper zinc tin sulfide (CZTS) provides a photovoltaic capability with favorable optical and electronic properties. Crystalized into either kesterite or wurtzite phases in aqueous or organic solution, CZTS represents potential application in the field of solar cell. Low cost and easy producing material methylammonium lead halide perovskite CH3NH3PbX3 (X=I, Br and Cl) possess superior optoelectronic properties, it represents a great potential for a variety of applications, such as high-efficiency photovoltaic cells and light-emitting diodes, but the involvement of toxic element and the instability is a concerning issue. Some efforts are in progress in the recent years to replace it with nontoxic and stable varieties such as cesium tin halide (CsSnX3, X=Cl, Br, I) and the derivative Cs2SnX6 (X=Cl, Br, I). Ternary I–III–VI semiconductor CuInS2 possesses unique properties such as large Stokes shift and high absorption coefficient. By doping with lanthanide ion Gd3+, the dual-modal MRI contrast agent with good relaxivity and fluorescent probe-CuInS2@ZnS:Gd3+ quantum dots have been investigated. Synthesized in a very simple way, the copper thiolate compounds exhibit bright emission in the optical region of green, yellow to white. The life time of copper thiolate is in the range of micrometers. These compounds possess interesting mechanochromic and thermochromism luminescent properties. The α-NaYbF4, β-NaGdF4, β-NaGdF4:(Yb,Tm), orthorhombic KYb2F7, α-KGdF4, α-KGdF4:(Yb,Tm), MGdF4:Ce@MGdF4:Eu/Tb, MGdF4:(Yb,Tm)@MGdF4:Eu/Tb, and MGdF4:Yb,Tm@MGdF4:Eu/Tb@MGdF4:Ce (M: Na or K) NPs have been synthesized hydrothermally. Under 365-400 nm UV excitation, the Eu3+/Tb3+ doped NaYbF4, NaGdF4 and KGdF4 samples emit red or green light. Not only by longer UV excitation, MGdF4:Ce@MGdF4:Eu3+/Tb3+ NPs and MGdF4:Yb,Tm@MGdF4:Eu3+/Tb3+@MGdF4:Ce NPs can also emit red or green light under short UV excitation 254 nm by a Ce3+-> Gd3+ -> Eu3+/Tb3+ energy transfer process. Under 980 nm NIR laser excitation, these potassium and sodium based core shell and core-shell-shell NPs emit red or green light by an energy transfer process of Yb3+ -> Tm3+-> Gd3+ -> Eu3+/Tb3+. The potassium based NPs exhibit brighter UCPL than sodium based NPs.

博士
國立臺灣大學
化學研究所
104
Nanomaterials (NMs) reveal unique chemical and physical properties based on small-sized effects, allowing their application as drug carriers, biosensors, and in bio-imaging. However, the safety of these NMs has also attracted attention because the complex interaction between NMs and organism can cause damage or cytotoxicity. This thesis focuses on developing a new type of highly efficient nanomedicine and investigating the cytotoxicity and safety of NMs. A multifunctional NM that consists of upconversion nanoparticles (UCPs) and Au NMs was fabricated for therapy and imaging. UCPs can convert light from high energy to low energy and serve as light source in multi-emission. Moreover, Au NMs generate heat when absorbing the light from UCPs through strong surface plasmon resonance (SPR). The difference in heat quality and distribution between sphere- or rod-shaped Au NMs was studied by photothermal effect and stimulation model. The efficiency of photothermal therapy (PTT) was tested through cell viability assay by irradiating with a 980 nm laser. Photodynamic therapy (PDT) was carried out by doping photosensitizer-methylene blue (MB) in the similar upconverting nanocomposites. MB was used to produce reactive oxygen species (ROS) in PDT to optimize the loading amount by changing the thickness of silica shell. In particular, the amount of ROS was further enhanced by conjugating with Au nanorods, which expectedly increased the absorption cross section of MB. The efficacy and mechanism among different SPR peaks were investigated and compared between sphere- and rod-shaped Au NMs. The low cytotoxicity of novel CuInS2 quantum dots (CIS QDs) was investigated because of the absence of contention. Caenorhabditis elegans was used as organism model with CIS QDs for toxicity study, and X-ray absorption near edge structure was employed to study the relationship between toxicity and chemical stability of CIS QDs under various treatment times. Moreover, TiO2 NMs with various sizes and structures were used to treat different human oral and lung cells to investigate the toxic effects. To determine the cellular response of cells to TiO2 NM treatment, we performed apoptosis assay and cell cycle analysis to identify the mechanism of cytotoxicity. Consequently, we successfully developed multifunctional NMs based on UCPs and Au NMs for PTT or PDT and bio-imaging. We also determined the factors that affected the low cytotoxicity for CIS QDs and the causes of damage from TiO2 NMs.

Thesis (Ph.D.)--University of Illinois at Urbana-Champaign, 2008.
Source: Dissertation Abstracts International, Volume: 69-11, Section: B, page: 6638. Adviser: Yi Lu. Includes bibliographical references. Available on microfilm from Pro Quest Information and Learning.