Дисертації з теми "MODIFIED HYDROGELS"

In this study, pH-sensitive poly(acrylamide-co-acrylic acid) hydrogels were synthesized as controlled release systems in the presence of N,N-methylene bisacrylamide as crosslinker and ammonium persulfate as initiator. A set of hydrogels were used in the form they were prepared. One set of hydrogels were prepared as porous networks by incorporating sodium chloride into the reaction medium and then leaching of it after the completion of polymerization reaction. Two sets of hydrogels were modified by argon-plasma at different discharge powers. Hydrogels were characterized by 13C-NMR, XPS, SEM, ATR-FTIR, ESR as well as equilibrium degree of swelling (EDS) and contact angle measurements. Prepared hydrogels were loaded with a model antibiotic, ciprofloxacin-HCl (CPFX), and in-vitro release of CPFX from hydrogel matrices were examined in buffer solutions of varying pH values. There are two factors determining the release rates of CPFX
one is the pH-dependent solubility of CPFX and the other is EDS of the hydrogel samples. For porous samples drug loading and release rates were higher when compared to the control samples and CPFX solubility dominated over release kinetics. Plasma treatment resulted in prolonged release rates in acidic medium.

The prevalence of cardiovascular disease and myocardial infarction-induced heart failure has risen significantly over recent years, emphasising the need for new, effective therapeutic strategies. A promising alternative approach is the cardiac delivery of potentially cardioprotective and regenerative growth factors from biomaterial scaffolds. One hydrogel system that has promise in this area is an injectable enzymatically degradable polyethylene glycol (PEG) hydrogel. Two modifications aimed at further optimising this system as a regenerative medicine scaffold were explored. Firstly, the covalent addition of heparin into the PEG backbone was assessed for its ability to stimulate angiogenesis by assessing the controlled release of basic fibroblast growth factor (bFGF), vascular endothelial growth factor (VEGF) and placental growth factor 2 (PlGF-2), and also assaying endothelial cell sprouting in an in vitro 3D spheroid angiogenesis assay. The second modification involved overlaying an increasingly hydrolytic degradability on top of the enzymatically degradable background of the hydrogel. The potential of this modification to regulate the rate of hydrogel replacement by invading tissue was assessed in the 3D spheroid assay and a subcutaneous implant study in a rat model. The covalent coupling of heparin was found to substantially increase the rate of release of bFGF, VEGF and PlGF-2 over 20 days by 23%, 42% and 19%, respectively, relative to nonheparinised PEG hydrogels (p<0.01). A 3D spheroid-based angiogenesis assay was modified for use in quantifying endothelial cell sprouting in PEG hydrogels. bFGF and VEGF were shown to elicit a significant increase (2.3 – 2.4-fold increase) in average cumulative sprout lengths relative to that seen in the control spheroids (p<0.01). However, PlGF-2 did not stimulate a significant response (1.4-fold increase, p=NS). In follow up studies with heparinised hydrogels, it was found that the 3D angiogenesis was not rigorously established and ways forward are discussed. Enzymatically degradable PEG hydrogels that retained their enzymatic degradability with increasing levels of potential for hydrolysis were formed by increasing the proportion of PEGacrylate (PEG-Ac) and correspondingly decreasing the portion of PEG-vinyl sulfone (PEG-VS) monomers. PEG-Ac forms hydrolytically unstable bonds with the peptide crosslinker whilst 4 PEG-VS forms stable linkages. This approach was shown through swelling studies to be capable of generating a range of hydrolytic degradation rates. Sprouting of endothelial cells from PEG hydrogel embedded spheroids was shown to increase as the PEG-AC concentration increased. Importantly, the rate of tissue invasion in vivo was also shown to be positively correlated with the PEG-Ac concentration. The increased utility of these hydrogels to act as delivery vehicles for therapeutic agents, through covalent coupling of heparin, is promising for their use as regenerative medicine scaffolds. Additionally, so is the ability to finely tune tissue invasion by manipulating their hydrolytic degradability.

La première partie de cette thèse est dédiée à la modification de polyélectrolytes pour former des films de multicouche de polyélectrolytes (PEM) ayant des propriétés d’adhésion de protéine et de cellules bien contrôlées et modifiables par étirement. L’acide polyacrylique a été modifié avec des groupes latéraux phosphorylcholine (PC) à des taux de 25 % (PAA-PC) ou avec des chaînes oligo(éthylène oxyde) terminées par la biotine : (EO)nBiotine (n = 0, 3, 9 et 18) avec de taux de modification de 1, 5, 10 ou 25 %. Des PEM incorporant ces polymères lient spécifiquement la streptavidine et repoussent tout autre protéine. Les propriétés d’adsorption et la sélectivité de ces PEM ont été mesurées par microbalance à quartz. Sur un substrat de PDMS étirables, on a construit des PEM terminés par un PAA portant des RGD recouvert par deux couches contenant PAA-PC. Au repos, seuls les PC sont exposés et inhibent l’adhésion cellulaire ; sous étirement, les groupes RGD sous-jacents sont exposés et déclenchent l’adhésion de fibroblastes.La deuxième partie est consacrée à l‘étude d’acide polyméthacrylique modifié hydrophobiquement avec des chaînes alkyle liées par des esters à la chaîne principale. 3 chaînes différentes ont été greffées : -C12H25 ; -C18H35 et C4H8-OOC- C11H23 avec des taux de 1, 5 and 10 %. Ces polymères sont associatifs et forment des hydrogels dans des tampons physiologiques pour des taux de modifications de 5% et des concentrations supérieures à 4% en poids. Ces gels ont été caractérisés par des mesures rhéologiques. Leur incubation avec des lipases provoque une baisse de leur viscosité, interprétable par une coupure des esters. Quand les gels faits à partir du PAA-C12 sont incubés avec une culture de Pseudomonas aeruginosa, la viscosité baisse également, ce qui montre que les chaînes sont également coupées in vivo
The first part of this thesis is dedicated to the modification of polyelectrolytes to form polyelectrolyte films with controlled and stretch responsive cell and protein adsorption properties. Poly(acrylic acid) (PAA) was modified with side phosphorylcholine groups (PC) at rates of 25 % or with oligo(ethylene oxide) chains ended by biotin ((EO)nBiotin, (n =0, 3, 9 and 18) at 1, 5, 10 and 25 % modification rates. Polyelectrolytes multilayer films (PEM) containing these polyelectrolytes bind selectively streptavidin but repel all other proteins. The adsorption properties and selectivity were measured by quartz crystal microbalance. On a stretchable PDMS substrate, we have built PEM ended by PAA bearing RGD, covered by two PAA-PC layers on the top. Under rest, only the PC groups are exposed and prevent cell adhesion; when the film is stretched, the underlying RGD groups are exposed, and trigger adhesion of fibroblasts.The second part was consecrated to the study of poly(methacrylic acid) hydrophobically modified with alkyl chains connected through an ester moiety to the main chain. Three different chains were grafted -C12H25; -C18H35 and -C4H8- OOC-C11H23 with a rate of 1, 5 and 10 %. These polymers associate in water and form hydrogels in physiological buffer, for modification rates higher than 5 % and polymer concentrations higher than 4 wt. %. The gels were characterized by rheology. Their incubation with lipases resulted in a decrease of their viscosity, which could be interpreted by the cleavage of the hydrophobic side chains, by rheological tests. When the gels with PAA-C12 were incubated with a culture of Pseudomonas aeruginosa, their viscosity decreased, which shows that alkyle chains are also cleaved in vivo

Osteoarthritis (OA), a degenerative disease of articular joints, is the leading cause of chronic disability in the US and affects more than a third of adults over 65 years old. Due to the obesity epidemic and an aging population, the prevalence of OA is expected to rise in both young and old adults. There are no disease modifying OA drugs. Therefore, providing any treatment options that delay the onset or progression of OA is highly desirable. The scope of this dissertation examines two different strategies to promote translational therapies for OA. The first approach investigated whether Smad ubiquitin regulatory factor 2 (Smurf2), an E3 ubiquitin ligase, could be a potential therapeutic target for OA. The second approach examined the incorporation of small chemical residues to enhance the physical and bioactivity of a bioinert scaffold for cartilage tissue repair. Overexpression of Smurf2 in chondrocytes was shown to accelerate spontaneous OA development in mice. We hypothesized that reduced Smurf2 expression could slow the progression of OA and enhance the performance of cells for cartilage repair. By performing surgical destabilization of the medial meniscus (DMM) on Smurf2-deficient mice, loss of Smurf2 was shown to mitigate OA changes in young mice but this protection diminished in older mice. Assessment of Smurf2-deficient chondrocytes in vitro revealed an upregulation of chondrogenic genes compared to wild-type; however, these differences were not seen at the protein level, deterring its potential use for cell-based therapies. During the course of this study, new insights about how age and sex affects different joint compartments in response to DMM surgery were also uncovered. These results broadened existing understanding of DMM-induced OA in mice but also questioned the validity of such a model to identify disease modifying targets that are translatable to OA in humans with advanced age. Due to a lack of innate repair mechanisms in cartilage, damage to cartilage increases the risk of developing OA early. Tissue engineering provides a unique strategy for repairing damaged cartilage by delivering cells in a well-controlled environment that can promote the formation of neotissue. We hypothesized that synthetic chemical residues could enhance the mechanical properties of a bioinert scaffold and promote matrix production of encapsulated chondrocytes. Covalent incorporation of small anionic or zwitterionic chemical residues in a polyethylene glycol-based hydrogel improved its stiffness and resistance to fluid flow, however, the resulting physical environment can also exert a dominant negative effect on matrix production of encapsulated chondrocytes. These results suggest that modulating the biosynthesis of chondrocytes with biochemical signals requires a concurrent reduction in any conflicting mechanotransduction signaling, emphasizing the importance of a degradable system to promote new cartilage formation. In summary, this dissertation establishes Smurf2 as a modulator of OA progression but implies that other factors such as age or protein(s) with redundant Smurf2 functions may play a role in limiting its effect as a therapeutic target. This work also reveals fundamental biology about how chondrocytes behave in response to physical and chemical cues in their microenvironment, which will aid in the design of better scaffolds for cartilage tissue engineering.

Ce memoire est consacre a la caracterisation, aux applications et a la modelisation cinetique d'electrodes modifiees par des hydrogels de laponite expansee par des oligosilsesquioxanes et fonctionnalisee par des especes electrocatalytiques (microparticules de metaux nobles, mediateurs redox, enzymes). Les etudes physico-chimiques et electrochimiques de ce nouveau materiau hybride d'electrode ont mis en evidence l'intercalation des oligosilsesquioxanes et l'existence d'une micro-porosite induite susceptible d'etre conservee en milieu organique. La stabilite des films obtenus ainsi que leur propriete d'echange d'ions offrent de larges potentialites d'application qui ont ete demontrees par plusieurs exemples en electrocatalyse (hydrogenation electrocatalytique) et en electroanalyse (biocapteurs amperometriques). En particulier, l'immobilisation de la polyphenol oxydase (ppox) permet l'elaboration d'un capteur sensible aux composes phenoliques aussi bien en milieux aqueux qu'en milieu organique. Les performances analytiques de ce capteur, tant en sensibilite, temps de reponse qu'en seuil de detection, comptent parmi les meilleures jusqu'ici decrites pour de tels systemes. Enfin, la modelisation cinetique du systeme electroenzymatique catechol/ppox qui met en jeu dans son fonctionnement une regeneration electrochimique du substrat de l'enzyme, a permis de rationaliser le processus d'amplification electroenzymatique responsable des limites de detection extremement basses de ce type de capteur. L'ensemble de ces etudes nous a ainsi permis de proposer une structure mesoporeuse de l'hydrogel enzyme-laponite expansee et de quantifier les modes de transport et d'amplification electroenzymatique.

For clinical translation of a pancreatic substitute, long-term storage is essential, and cryopreservation is a promising means to achieve this goal. The two main cryopreservation methods are conventional freezing and vitrification, or ice-free cryopreservation. However, as both methods have their potential drawbacks for cryopreservation of a pancreatic substitute, they must be systematically evaluated in order to determine the appropriate method of cryopreservation. Furthermore, previous studies have indicated benefits to encapsulation in 3-D adhesive environments for pancreatic substitutes and that adhesion affects cell response to cryopreservation. Thus, the overall goal of this thesis was to investigate cryopreservation effects on model pancreatic substitutes consisting of cells encapsulated in non-adhesive and adhesive 3-D alginate hydrogels. Murine insulinoma betaTC-tet cells encapsulated in unmodified alginate hydrogels were chosen as the model pancreatic substitute in a non-adhesive 3-D environment. Murine myoblast C2C12 cells, stably transfected to secrete insulin, encapsulated in partially oxidized, RGD-modified alginate hydrogels were chosen as the model pancreatic substitute in a 3-D adhesive environment. With respect to cryopreservation effects on intermediary metabolism of betaTC-tet cells encapsulated in unmodified alginate, results indicate that relative carbon flow through the tricarboxylic acid cycle pathways examined is unaffected by cryopreservation. Additionally, insulin secretory function is maintained in Frozen constructs. However, vitrification by a cryopreservation cocktail referred to as DPS causes impairment in insulin secretion from encapsulated betaTC-tet cells, possibly due to a defect in late-stage insulin secretion. Results from Stable C2C12 cells encapsulated in RGD vs. RGE-alginate indicate that up to one day post-warming, cell-matrix interactions do not affect cellular response to cryopreservation after vitrification or freezing. Although there are differences in metabolic activity and insulin secretion immediately post-warming for DPS-vitrified RGD-encapsulated Stable C2C12 cells relative to Fresh controls, metabolic activity and insulin secretion are maintained at all time points assayed for Frozen constructs. Overall, due to results comparable to Fresh controls and simplicity of procedure, conventional freezing is appropriate for cryopreservation of betaTC-tet cells encapsulated in unmodified alginate or Stable C2C12 cells encapsulated in partially oxidized, RGD-modified alginate.

This diploma thesis deals with hyaluronan modified by palmitoyl and its gelation. Gels were created from palmitoyl hyaluronan with molecular weight 216 kDa and degree of substitution 11 % in concentrations 15 and 20 g dm-3 in water and concentrations 10, 15, 20 g dm-3 in NaCl and TSB. Also gel from palmitoyl hyaluronan with molecular weight 35 kDa and degree of substitution 10 % in concentrations 20, 30 g dm-3 in NaCl was created. Gels were investigated concerning medical applications. Gels were rigid and had very good properties, which was confirmed by rheology. The physical properties (pH, water content) of gels and stability were investigated. On the grounds of the MTT test, three methods of cell incorporation were suggested. Gels are nontoxic, biocompatible, and biodegradable with nontoxic degradation products and that is why they are excellent aspirants for use in biomedicine.

The aim of master thesis was to study structural and transport properties of PVA films modified with method of semi-IPN with suitable polyectrolytes and plasticizers. The first important step was optimalization of PVA films preparation, when time of heating was set at 90 °C for 1 hour. Drying was set at 50 °C for 24 hours. Molecular weight of PVA was chosen 85–124 kDa in concentration 10 wt.%. For preparation of PVA-based semi-IPN thin films polyelectrolytes (polyglutamic acid, DEAE-dextran hydrochloride) and plasticizer (glycerol) were selected. Basic characterization of prepared materials was performed with FTIR, TGA, SEM and specific surface analysis. The difference between modified PVA films was in the chargé of individual functional groups carried by used polyelectrolytes. Surfaces of all the PVA films were smooth without visible defects. Transport properties were characterized with the method of horizontal diffusion cell with methylen blue used as a probe. Diffusion coefficients of methylen blue through PVA films were determined. It was found, that the fastest pass was throw PVA film without additives. The slowest diffusion was observed through PVA/DEAE-dextran film, because of the same charge of the film with a probe. PVA/PGA reacted with methylen blue to form a complex. Plasticizer effect on the diffusion was only minor; it caused a slight decrease of diffusion coefficient. These films were easier to handle.

Common problems encountered in clinical sensing are those of non-biocompatibility, and slow response time of the device. The latter, also applying to chemical sensors, is possibly due to a lack of understanding of polymer support or membrane properties and hence failure to optimise membranes chosen for specific sensor applications. Hydrogels can be described as polymers which swell in water. In addition to this, the presence of water in the polymer matrix offers some control of biocompatibility. They thus provide a medium through which rapid transport of a sensed species to an incorporated reagent could occur. This work considers the feasibility of such a system, leading to the design and construction of an optical sensor test bed. The development of suitable membrane systems and of suitable coating techniques in order to apply them to the fibre optics is described. Initial results obtained from hydrogel coatings implied that the refractive index change in the polymer matrix, due to a change in water content with pH is the major factor contributing to the sensor response. However the presence of the colourimetric reagent was also altering the output signal obtained. An analysis of factors contributing to the overall response, such as colour change and membrane composition were made on both the test bed, via optical response, and on whole membranes via measurement of water content change. The investigation of coatings with low equilibrium water contents, of less than 10% was carried out and in fact a clearer signal response from the test bed was noted. Again these membranes were suprisingly responding via refractive index change, with the reagent playing a primary role in obtaining a sensible or non-random response, although not in a colourimetric fashion. A photographic study of these coatings revealed some clues as to the physical nature of these coatings and hence partially explained this phenomenon. A study of the transport properties of the most successful membrane, on a coated wire electrode and also on the fibre optic test bed, in a series of test environments, indicated that the reagent was possibly acting as an ion exchanger and hence having a major influence on transport and therefore sensor characteristics.

Titanium dioxide (TiO2) is a wide-band gap semiconductor with band gaps around 3 eV for the principal polymorphs rutile and anatase. Although TiO2 has been commercialized in applications that utilise its special chemical and optical properties, its band gap should be reduced to improve its performance, especially as an active photo catalyst. Band gap engineering of TiO2 has therefore attracted many researchers looking to extend its applicability as a functional material. Reduction of TiO2 introduces oxygen vacancies, initially forming disordered TiO2–x and eventually forming the ordered Magnéli phases TinO2n–1 ( n 1 x ), which have been commercialized in battery electrodes. Reduction of TiO2 under a hydrogen atmosphere is a promising method which can increase the visible-light absorption efficiency of TiO2, but the mechanism by which hydrogen exposure enhances its electrical properties is subject to controversy. TiO2 can also be reduced by carbon-containing gases, including CO, CO2 and CH4. Using methane as a reducing agent has the advantage of consuming a greenhouse gas in favour of producing oxygen deficient TiO2 for cocatalyst free methane decomposition processes. Reduced rutile is bluish in colour, while reduced anatase is black. Slightly reduced anatase or rutile nanoparticles have been reported to be yellow. Hydrogen-modified TiO2 In the first part of the project, carried out at Griffith University, the focus was on fundamentals, particularly the production and influence of O vacancies under vacuum and hydrogen, aiming to understand the action of hydrogen as a reducing agent. Oxygen deficient TiO2‒x was produced by exposing rutile to hydrogen at temperatures up to 500 C. Magnéli phases were produced by exposing rutile to vacuum at temperatures up to 1100bC. The absorption and desorption of hydrogen were studied by thermogravimetric analysis at temperatures up to 730 C, with simultaneous mass spectrometry measurements. The structural modifications caused by hydrogen absorption and desorption were confirmed by in-situ x-ray powder diffraction measurements at temperatures up to 1100 C. It was found that the Magnéli phases produced also absorbed hydrogen and desorbed higher amounts than hydrogen-modified rutile. Recent explanations of the enhancement of the electrical properties of hydrogen-modified TiO2 propose mid-band gap states just below the conduction band and, based on the absence of obvious structural changes in x-ray diffraction measurements, relate these to surface disorder. The reasoning behind this conclusion is that the volume of material subject to structural change must be too small to contribute noticeably to the measured diffraction pattern. On the other hand, x-ray diffraction is insensitive to light elements such as oxygen. In-situ high-resolution neutron powder diffraction with deuterium in place of protium was carried out to test this hypothesis, based on the high neutron scattering length of O relative to Ti. A small contraction of the unit cell was found, accompanying the introduction of oxygen vacancies. By refining the O occupancy, it was determined that TiO2–x with x = 0.2 (equivalent in stoichiometry to a Ti5O11 Magnéli phase) was formed under 50 bar of deuterium at 500 C. This indicates that vacancies are introduced throughout the volume of the TiO2 particle, because a surface-only structural change would not be resolvable. The sample was bluish in colour as is usual for reduced rutile. It therefore appears that the explanation of enhanced electrical properties owing to surface-only processes is wrong, or at best incomplete. Reduction and Carburization of TiO2 by Methane The second part of the project, carried out at University of California Santa Barbara, focused on applications of reduced TiO2. TiO2 reduction was studied using methane-containing gas (CH4-H2-Ar). In addition, catalytic decomposition of methane to hydrogen and carbon over reduced TiO2 surface was investigated. Oxide reduction using methane-containing gas occurs through adsorption and dissociation of methane with formation of adsorbed active carbon. Methane decomposition on metal oxides and solid solutions has been limited by carbon formation and deactivation. Carbon formation in the alkane dehydrogenation process is problematic because even small amounts of carbon can deactivate catalytic surfaces by physically blocking active sites. Methane pyrolysis experiments were performed in a lab-scale fixed-bed reactor and molten salt environment by flowing CH4 through a molten halide (LiCl-KCl eutectic mixture)/TiO2(Degussa P25) mixture. The highest degree of CH4 conversion (~34% initially) occurred at 1000 °C, but owing to catalyst coking and sintering fell quickly to ~20.0%. Temperature-programmed reaction (TPR) was also performed on the molten salt/additives mixture. The H2 yield of the LiCl-KCl/TiO2 mixture was not much higher than that of plain salt. The salt mixture turned yellow and TiO2 particles precipitated in the bottom of the reactor. Since it is known that CH4 reduces TiO2 to TiO2–x, the yellow colour of the molten salt/TiO2 mixture was likely due to the presence of TiO2–x. The higher density of the TiO2 particles relative to the molten salt, and ability to be wetted by the molten salt, caused them to settle in the reactor. It is concluded that the precipitation of TiO2 particles in the bottom of the reactor caused the low yield of the salt/catalyst mixture. More experiments should be done to confirm the catalytic activity and stability of TiO2 and Magnéli phases for methane pyrolysis.
Thesis (PhD Doctorate)
Doctor of Philosophy (PhD)
School of Natural Sciences
Science, Environment, Engineering and Technology
Full Text

Une nouvelle plateforme hydrogel uniquement formée par l’association de nanocapsules lipidiques (NCLs) a été développée en s’inspirant de précédents travaux utilisant une gemcitabine modifiée. Afin de limiter la toxicité de l’hydrogel, la gemcitabine a été remplacée par la cytidine, rendue amphiphile par une chaîne aliphatique (Cyt-C16). Placée à l’interface huile/eau des NCLs, la Cyt-C16 permet la formation d’un réseau tridimensionnel de NCLs à l’origine de la gélification. Un plan de mélange a permis d’optimiser les procédés de formulation de 4 tailles de NCLs modèles. Les propriétés viscoélastiques des hydrogels sont modulables. Plus les concentrations en NCLs et Cyt-C16 sont élevées, plus le gel est « rigide », indépendamment de la taille des NCLs qui doit être supérieure à 50 nm pour permettre la gélification. Les hydrogels sont injectables et permettent une libération prolongée de NCLs (de taille mono-disperse), sans toxicité supplémentaire in vitro, du fait de la présence de la Cyt-C16. De plus, uniquement solubilisée dans l’huile,la Cyt-C16 permet d’obtenir un organogel, dont les propriétés viscoélastiques sont renforcées en augmentant sa concentration. L’injection sous-cutanée (SC) in vivo des deux gels est bien tolérée et entraine une réaction inflammatoire locale comparable à celle provoquée par un excipient pharmaceutiquement acceptable. Ces deux formes pourront être utilisées pour libérer de façon prolongée différents actifs. Deux applications précliniques des hydrogels ont été explorées, l’une utilisant la voie SC pour cibler les ganglions lymphatiques, la seconde permettant un traitement local des suites opératoires d’une résection de glioblastome
An innovative hydrogel platform obtained by the association of lipid nanocapsules (LNCs) was based on the previous work on modified gemcitabine. To limit the inherent toxicity of the hydrogel, gemcitabine was replaced by cytidine, then modified by an aliphatic chain (Cyt-C16). The hydrogel network was allowed by H-bond interactions between cytidine moieties exposed at the oil/water interfaces of LNCs. An experimental plan provided the formulation processes for 4 optimized sizes of model LNCs. The gelation was only possible for LNC sizes higher than 50 nm, and the hydrogel viscoelastic properties are versatile. The hydrogel is more “rigid” when LNC and Cyt-C16 concentrations increase, independently of the LNC size. The hydrogels are injectable and allow a sustained release of LNCs (withmonodisperse size), without additional in vitrocytotoxicity due to Cyt-C16. Moreover, when solubilized in oil, Cyt-C16 alone produced an organogel platform, whose viscoelastic properties are strengthened increasing its concentration. Both types of gels showed a good biocompatibility after an in vivo subcutaneous (SC) injection, with a local inflammatory response similar to that of induced by an approved excipient. These two forms could be used to sustain the release of various drugs, and two preclinical applications of hydrogels have been explored : one using the SC route to target lymph nodes, and the second for local treatment after glioblastoma resection

Artificial Photosynthesis (AP) focuses on finding a way to harness solar energy to generate a chemical fuel. TiO2 semiconductors are of interest to AP research due to its relatively low cost and widespread use as an efficient charge-separating support. This research focuses on the development of a device for photocatalytic hydrogen generation. Our approach utilizes the immobilization of iron polypyridyl catalysts and ruthenium chromophores on TiO2 through stable phosphonic acid anchoring groups.

NiSi is an attractive material in the production of CMOS devices. The problem with the utilization of NiSi, is that there is no proper method of cleaning the oxide on the surface. Sputtering is the most common method used for the cleaning, but it has its own complications. Dry cleaning methods include the reactions with radicals and these processes are not well understood and are the focus of the project. Dissociated NF3 and NH3 were used as an alternative and XPS is the technique to analyze the reactions of atomic fluorine and nitrogen with the oxide on the surface. A thermal cracker was used to dissociate the NF3 and NH3 into NFx+F and NHx+H. There was a formation of a NiF2 layer on top of the oxide and there was no evidence of nitrogen on the surface indicating that the fluorine and hydrogen are the reacting species. XPS spectra, however, indicate that the substrate SiO2 layer is not removed by the dissociated NF3 and NiF2 growth process. The NiF2 over layer can be reduced to metallic Ni by reacting with dissociated NH3 at room temperature. The atomic hydrogen from dissociated ammonia reduces the NiF2 but it was determined that the atomic hydrogen from the ammonia does not react with SiO2.

Thesis (M.S.)--Southern Illinois University Carbondale, 2007.
"Department of Mechanical Engineering and Energy Processes." Includes bibliographical references (leaves 54-59). Also available online.

Neste trabalho foi estudado o comportamento eletroquímico de materiais à base de carbono Printex 6L, sem e com a adição de compostos orgânicos da classe das quinonas (2-terc-butil-9,10-antraquinona (TBA) e 2-etil-9,10-antraquinona (EA)) para a produção de peróxido de hidrogênio (H2O2) a partir da reação de redução do oxigênio gasoso (O2). Na primeira etapa, foi utilizada a técnica de microcamada porosa depositada sobre um eletrodo de disco/anel rotatório, sendo que a partir dos resultados obtidos foram confeccionados eletrodos de difusão gasosa (EDG) para a eletrogeração de H2O2. Os melhores resultados utilizando a microcamada porosa foram para os materiais com a adição dos modificadores, sendo que o material com 1,0% (m/m) de TBA na demonstrou ser o mais eficiente na geração de peróxido de hidrogênio, apresentando eficiência 20% maior comparado ao Printex 6L sem modificador. Com o eletrodo de difusão gasosa confeccionado com o composto orgânico escolhido, na melhor porcentagem de adição mássica de modificador, obteve-se a concentração de 301 mg L-1, sendo que com o eletrodo confeccionado com Printex 6L sem modificador obteve-se a concentração de 175 mg L-1, sob as mesmas condições experimentais. A eficiência cinética também apresentou os mesmos resultados quanto à eficiência dos materiais escolhidos, sendo de 5,94 mg L-1 min-1 para o material com 1,0% de TBA, no potencial de -1,0 V (vs. ECS), e de 3,05 mg L-1 min-1 para o eletrodo de difusão gasosa sem modificador, no potencial de -0,8 V (vs. ECS).
In this work, the electrochemistry behavior of the materials prepared with Printex 6L, with and without addition of organic compounds of the class of quinones, being the compounds: 2-tert-butyl-9,10-anthraquinone (TBA) and 2-ethyl-9,10-anthraquinone (EA). These materials were used to promote the electrogeneration of hydrogen peroxide through the oxygen reduction reaction. In the first phase, it was used the technique of porous microlayer deposited on the rotating ring/disk electrode, and after has been confectioned gas diffusion electrodes (GDE). The best results using the porous microlayer were for the materials with addition of modifiers, and the material with 1.0% (m/m) of 2-terc-butyl-9,10-anthraquinone was demonstrated to be the most efficient in generating hydrogen peroxide, presenting an efficiency 20% higher when compared to Printex 6L without the modifier. The gas diffusion electrode made with the chosen organic compound, in the best massic percentage of modifier, obtained the concentration of 301 mg L-1, and the electrode made with Printex 6L without the modifier obtained the maximum concentration of 175 mg L-1, under the same experimental conditions. The kinect efficiency also demonstrated the same results regarding the efficiency of the chosen materials, which means 5.94 mg L-1 min-1 for the material with 1.0% of 2-terc-butyl-9,10-anthraquinone, in the potential of -1.0 V(vs. SCE), and 3.05 mg L-1 min-1 for the gas diffusion electrode without the modifier, in the potential of -0.8 V (vs. SCE).

Nitrogen-doped carbon materials have garnered much interest due to their abilities to behave as electrocatalysts for reactions important in energy production (oxygen reduction) and biosensing (hydrogen peroxide reduction). Here, we demonstrate fabrication methods and determine electrocatalytic properties of nitrogen-doped screen-printed carbon (N-SPCE) electrodes. Nitrogen doping of graphite was achieved through a simple soft-nitriding technique which was then used in lab-formulated screen-printing inks to prepare N-SPCEs. N-SPCEs displayed good electrocatalytic activity, reproducibility and long term stability towards the electrochemical reduction of hydrogen peroxide. N-SPCEs exhibited a wide linear range (20 µM to 5.3 mM), reasonable limit of detection of 2.5 µM, with an applied potential of -0.4 V (vs. Ag/AgCl). We also demonstrate that nitrided-graphite can similarly be used as a platform for the deposition of electrocatalytic platinum nanoparticles, resulting in Pt-N-SPCEs with a lower limit of detection (0.4 µM) and better sensitivity (0.52 µA cm-2 µM-1) towards H2O2 reduction.

The main purpose of this work is study of electrochemical hydrogen peroxide and ascorbate reactions on electrodes modified by Prussian blue (PB), with the aim to apply these electrodes in creation of sensors and biosensors. For this purpose, a detailed study of electrochemical reduction of hydrogen peroxide, as well as of oxidation of ascorbate at Prussian blue modified rotating disk electrode. In view of the results obtained, a mechanism for hydrogen peroxide reduction at PB modified electrode has been proposed. In accordance with this mechanism, electron transfer appears to be rate-limiting step. The kinetics of decomposition of PB modified electrode in the course of a cathodic reduction of hydrogen peroxide has been studied, and the influence of different factors to this process has been determined. Prototypes of sensors and biosensors, for different analytes have been elaborated and tested.
Darbo tikslas yra elektrocheminių vandenilio peroksido ir askorbato reakcijų tyrimas ant Berlyno mėlynuoju (BM) modifikuotų elektrodų, siekiant pritaikyti šiuos elektrodus jutiklių ir biojutiklių kūrimui. Ištirta vandenilio peroksido redukciją ir askorbato oksidaciją naudojant sukamojo disko elektrodą. Gauti rezultatai galimai įrodo stadijinį vandenilio peroksido katodinės redukcijos mechanizmą vykstantį ant BM modifikuoto elektrodo. Detaliai ištirta BM sluoksnio irimo kinetika vandenilio peroksido elektroredukcijos metu, ir nustatyti faktoriai, įtakojantys irimo proceso greitį. Sukurti jutiklių ir biojutiklių prototipai, kurie galėtų būti panaudoti biologiškai aktyvių medžiagų (vandenilio peroksido, askorbato, gliukozės) nustatymui.

This thesis presents the synthesis and characterization of modified graphene materials and investigates their role in sustainable energy storage applications by using both experimental methods and density functional theory simulations. The outcomes obtained provide a better understanding of the structure-property relationship in modified graphene and its role in electrochemical process in rechargeable batteries, benefiting the development of high-performance electrode materials.

Facultative phototrophic bacterium Rhodobacter capsulatus has two c-type electron carrier cytochromes (cyt)
the soluble cyt c2 and the membrane-attached cyt cy, that act as electron carriers during respiratory and photosynthetic growth of this species. Previously, a soluble form of cyt cy was constructed by fusing genetically the signal sequence of cyt c2 to the cyt c domain of cyt cy. The obtained novel soluble cyt cy (cyt S-cy) was unable to support photosynthetic growth of R. capsulatus but yielded photosynthetically functional (Ps+) revertants frequently. In the first part of this study, photosynthetic electron transfer properties of some of Ps+ revertants of cyt S-cy were analyzed by biochemical and biophysical methods and compared with the cyt cy and cyt c2. Reduction-oxidation titration of membrane supernatants showed that the redox midpoint potential of cyt S-cy was +338 mV which is similar to midpoint potentials of cyt cy or the cyt c2. However, light-activated, time resolved spectroscopy revealed that reaction center mediated oxidation kinetics of cyt S-cy exhibited only a slow phase, unlike cyt c2 which has both fast and slow phases. It therefore appeared that during electron transfer cyt S-cy does not interact with the reaction centre as tightly as cyt c2. These findings imply that attaching electron carrier cyts to the membrane allowed them to weaken their interactions with their partners, while restricting their spatial diffusion, so that they accomplish rapid multiple turnovers. In the second part of this study, hydrogen production of various R. capsulatus strains harboring the genetically modified electron carrier cytochromes, cyt cbb3 deleted and Qox deleted strains were compared with the wild type. Under photoheterotrophic growth conditions with limiting nitrogen source, the excess reducing equivalents generated by organic acid oxidation are consumed to reduce protons into hydrogen by the activity of nitrogenase in R. capsulatus. The results indicated that the hydrogen production of mutant strains with modified electron carrier cytochromes decreased 3-5 folds, and the hydrogen production rate of the cyt cbb3- mutant increased significantly. Moreover in this study, the hydrogen production efficiency of different R. capsulatus strains was increased by the chromosomal inactivation of uptake hydrogenase genes and enzymatic activity of uptake hydrogenase of R. capsulatus strains were determined.

Les travaux décrits dans ce mémoire sont consacrés au développement de nouveaux dérivés amphiphiles de l'acide hyaluronique (HA) obtenus par greffage de chaînes alkyle hydrophobes le long de la chaîne macromoléculaire hydrophile. La stratégie de greffage présentée a été optimisée afin de pouvoir transposer la synthèse à l'échelle industrielle. Le comportement en milieu aqueux des polymères natifs et les propriétés viscoélastiques des systèmes associatifs ont été étudiés par des mesures rhéologiques en écoulement et en régime dynamique. Une modulation des propriétés physico-chimiques est obtenue par la variation de la longueur de la chaîne du HA, de l'hydrophobicité des greffons et/ou de l'introduction dans le système associatif des molécules hôtes (alpha et beta cyclodextrines) ou des tensioactifs. Des expériences de titration calorimétrique couplées à de la RMN bidimensionnelle (ROESY), à des mesures de viscosités et à la modélisation moléculaire ont permis, suite à une analyse détaillée, d'élucider les interactions entre des HA alkylés et des cyclodextrines. Au cours de ce travail, nous avons présenté différents types de produits industriels développés par des sociétés européennes et américaines en tant que viscosupplément, la viscosupplémentation étant l'application visée pour nos dérivés développés dans le cadre de cette thèse.

Dans ce travail, nous nous sommes intéressés à la synthèse de nouveaux hydrogels, obtenus en réticulant chimiquement, par une réaction thiol-ène, des polyélectrolytes (PAA) modifiés par des groupes alkyle greffés le long de la chaîne. L'hydrogel ainsi formé est donc composé d'un réseau à la fois physique, du à l'agrégation des groupements hydrophobes en micelles, et chimique. Par comparaison avec un hydrogel de PAA « modèle » (non hydrophobe), nous étudions les phénomènes dissipatifs que le réseau transitoire peut induire, en nous intéressant plus spécialement aux grandes déformations, par le biais d'expériences de compression uniaxiale. Dans le domaine d'élasticité linéaire, nous avons identifié une forte composante viscoélastique due aux agrégats hydrophobes, ceux-ci n'affectant cependant pas le module élastique du gel, comparativement au gel non modifié. Les expériences aux grandes déformations ont mis en évidence un mécanisme supplémentaire d'agrégation causé par des interactions électrostatiques attractives entre chaînes de PAA. Ce phénomène, induit par la déformation, est fortement couplé à la dissipation d'énergie causée par les réorganisations des agrégats hydrophobes soumis à la contrainte. Les agrégats hydrophobes améliorent de façon non négligeable la résistance à la rupture du réseau comparativement aux gels non modifiés. Des résultats préliminaires de fracture sont également présentés.

The development of an accurate, sensitive, and selective hydrogen peroxide (H2O2) diagnostic device with a low detection limit is important in the fields of biology and medicine. Numerous approaches have been reported for electrochemical detection of H2O2. These approaches exhibit good stability and selectivity with a low detection limit, but involve a complicated fabrication process. We designed and fabricated three enzyme-free H2O2 biosensors by coating a three-dimensional open-pore nickel foam (3D-Ni foam) electrode with heme proteins, namely, (hemoglobin (Hb), myoglobin (Mb), and cytochrome c (Cyt.c)). The heme protein-modified Ni foam can be directly used as electrodes, thereby simplifying the electrode fabrication process and offering advantages, such as enhanced electrode–electrolyte contact area and minimum diffusion resistance. Heme proteins can function as a redox mediator for shuttling electrons on the electrode–electrolyte interface and for engaging sufficient electro-active species exposed on the surface of the Ni foam for the Faradaic redox reaction. The immobilization of the heme proteins onto the 3D Ni foam was analyzed using scanning electron microscopy, UV-visible spectroscopy, contact angle, and Raman spectroscopy. The heme proteins maintained their biological functions and effective electronic connection and affected the interfacial properties of the Ni foam after immobilization. The electrochemical effects of the Ni foam electrodes modified with similar concentrations of different heme proteins (Hb, Mb, and Cyt.c) in the selective oxidation of H2O2 were investigated and compared. Hence, these electrodes can be applied in the analysis of real samples, such as apple juice.

The motivation for this work was provided by the results of an interdisciplinary, multi-university research programme funded by the Ministry of Defence. The significant finding in question was that the stress corrosion cracking (SCC) resistance of AISI type 304 stainless steel (SS) alloys can be significantly improved by the addition of the platinum group metals (PGM), ruthenium and palladium. The increased SCC resistance could be attributed to the enhancement of the cathodic hydrogen reduction reaction. Thus, the primary objective of this work was to confirm that the increase in hydrogen production at the surface would not counteract the improvement in SCC resistance by increasing the susceptibility to hydrogen embrittlement (HE). Electrochemical hydrogen charging was employed and melt extraction was used to measure the bulk concentration of absorbed hydrogen as a function of alloy chemistry. Both Ru and Pd doped experimental 304 SSs showed a decrease in the concentration of absorbed hydrogen compared to an experimental standard 304 SS (i.e., a controlled, non PGM-doped reference 304). This result is thought to be due to the PGMs enhancing the recombination kinetics of adsorbed hydrogen. Ru proved more effective than Pd at hindering absorption and this is likely associated to the more homogenous distribution of Ru in solid solution. Slow strain rate tensile (SSRT) testing was performed in air at sub-ambient temperatures on pre-hydrogen charged specimens. PGM addition was found not to increase the susceptibility of 304 to HE. Conversely, an approximately equal enhancement of the HE resistance was observed for the addition of both Ru and Pd. The modest improvements are attributed to the reduced concentration of absorbed hydrogen, with a further possible beneficial trapping effect of Pd concentrated bands, contributing to the HE resistance of Pd doped 304.

Les carbones poreux ont été largement utilisés et étudiés ces dernières années. Ce travail de recherche porte sur la préparation de matériaux carbonés mésoporeux modifiés ou non par de l'azote. Tout d'abord, un carbone mésoporeux pur a été synthétisé. Puis des atomes d'azote ont été introduits dans ce carbone mésoporeux par deux méthodes de dopage ("in situ" et "post-synthèse" respectivement). La comparaison des propriétés acido-basiques dans des conditions différentes pour les trois types de matériaux mésoporeux carbonés, avec ou sans diazote, a été faite grâce à des techniques calorimétriques. Ces carbones mésoporeux ont aussi été utilisés dans l'adsorption de polluants, le stockage de l'hydrogène et en tant que supports pour les métaux précieux et l'oxyde de fer en catalyse. Les différentes performances dans ces applications ont été mises en relation avec les différentes propriétés structurelles et surfaciques causées par le dopage au diazote
Porous carbon materials are widely used and studied in recent years. In this work, three kinds of mesoporous carbon materials were prepared. Firstly, cost-effective pure mesoporous carbon was synthesized. Then nitrogen atoms were introduced into the mesoporous carbon by “in situ” and “post” doping methods respectively. The comparisons of the acid-base properties in different conditions of the three kinds of mesoporous carbon materials with or without nitrogen were studied and revealed by different calorimetric techniques. The three kinds of mesoporous carbons were also applied in pollutants adsorption, hydrogen storage and as supports of precious metals and iron oxide in catalysis. The different performances in applications were related to the different structural and surface properties caused by the N-doping

L'objectif de cette these est d'evaluer le potentiel de l'interaction ionique dans la preparation d'assemblages supramoleculaires en solution aqueuse. Le processus d'association etudie est l'hetero-dimerisation de cyclodextrines modifiees portant des charges opposees sur leurs faces primaires : une -cyclodextrine hepta-carboxylee et des -, - et -cyclodextrines hexa-, hepta-, et octa-ammoniums. Une etude potentiometrique a permis d'atteindre les proprietes acido-basiques de ces unites, ainsi que de mesurer leur enthalpie libre de dimerisation, variant de 20 a 60 kj/mol. Au vu des valeurs elevees des constantes d'association experimentalement determinees, l'influence de l'agregation eventuelle d'un des reactifs ou produits sur la valeur apparente des constantes d'association a ete evaluee. La structure des hetero-dimeres (dimensions et orientation relative des sous-unites) a ete analysee par rmn (techniques de relaxation et experiences en gradient de champ), dans le cadre d'une description hydrodynamique des molecules en interaction. Enfin, l'incorporation de molecules fluorescentes a l'interieur de la cavite des hetero-dimeres a ete realisee. Les proprietes acido-basiques et la stabilite des assemblages supramoleculaires maintenus par interaction ionique a ete rationalisee sur des bases structurales. L'enthalpie libre de la formation de ces assemblages a ete quantifiee, et sa dependance vis-a-vis du produit des charges en interaction soulignee, en accord avec l'experience. La modulation attendue de la stabilite des hetero-dimeres par le ph a ete evaluee. Enfin, l'utilisation de cyclodextrines dans la preparation d'assemblages supramoleculaires s'est prolongee par l'etude de la dimerisation de cyclodextrines neutres par liaison hydrogene, en solution organique. La methode rmn d'etude structurale precedemment utilisee a ete transposee avec succes, en complement d'autres techniques plus classiques d'analyse physico-chimique des interactions.

Heterogeneous catalysts form a highly important part of everyday life, ranging from the production of fertiliser enabling the growth of crops that sustain much of the world's population to the production of synthetic fuels. They constitute a key part of the chemical industry and contribute towards substantial economic and environmental benefits. Heterogeneous catalysts are also believed to have an important role to play in a future hydrogen economy, reducing our requirements for fossil fuels. To this end, formic acid has been proposed as a potential hydrogen storage material for small portable devices. Additionally, formic acid has historically been used as a probe molecule to study catalyst materials and recent developments in the knowledge of its decomposition pathways and the preferred sites of these reactions, establish a good foundation for further study. This work explores a range of novel modification techniques that alter the activity of Pd nanoparticles to decompose formic acid to H₂ and CO₂. The methods used are the addition of polymers, attaching various functional groups to the surface of the catalyst support and decoration of nanoparticles with sub-monolayer coverages of another metal. Using a range of characterisation methods including FTIR of an adsorbed CO probe, XRD and XPS coupled with computational modelling, it is found that these methods result in some significant electronic and/or geometric alterations to the Pd nanoparticles. For polymer modification, the nature of the pendent group is highly important in determining the effects of the polymer on the Pd particles, with all the tested polymers resulting in varying degrees of electronic donation to the Pd surface. The geometric modifications caused by the polymers also varied with pendent groups; with amine containing pendent groups found to selectively block low coordinate sites, preventing the undesired dehydration of formic acid which results in poisoning of the Pd catalyst by the resulting CO. Attachment of amine groups to the surface of metal oxide catalyst supports, is demonstrated to result in dramatic electronic promotional effects to the supported Pd nanoparticles, and when an amine polymer is attached to the support surface the geometric modification is again observed. Finally decoration of Pd nanoparticles with a sub-monolayer coverage of a second metal is examined, resulting in some similar electronic and geometric effects on Pd nanoparticle surfaces to those observed with polymer modification with corresponding changes in formic acid decomposition activity. Overall, a number of methods are displayed to tune the catalytic activity and selectivity of Pd nanoparticles for formic acid decomposition, resulting in catalysts with some of the highest reported TOF's at room temperature. These modification methods are believed to be potentially applicable to a wide range of other catalytic reactions that operate under mild conditions.

Two specific drug-delivery applications were sought in this work using polyamidoamine (PAMAM) dendrimers. One drug-delivery system used a novel dendrimer hydrogel (DH) for sustained delivery of anti-glaucoma drugs. In this work, PAMAM G3.0 dendrimers were covalently bonded with poly(ethylene glycol) (PEG­12000) molecules which were subsequently acrylated, resulting in photocurable DH conjugates. For pharmacological studies, DH were loaded with a solution of intraocular pressure lowering drugs, brimonidine and timolol maleate, and were characterized for in vitro release and ex vivo transport and uptake. DH formulations were shown to increase the loading of drug molecules, increase transcorneal drug delivery, and exhibit sustained-delivery of drug molecules. A second drug-delivery system, utilizing cell-surface engineering, intended to increase the targeting ability of highly toxic anti-cancer drugs to curtail systemic effects. In particular, Qdots and 5-(aminoacetamido) fluorescein-labeled polyamidoamine dendrimer G4.5, both of which were coated with amine-derivatized polyethylene glycol, were immobilized to the sodium periodate-treated surface of RAW264.7 macrophages through a transient Schiff base linkage. Further, a reducing agent sodium cyanoborohydride was applied to reduce Schiff bases to stable secondary amine linkages. The distribution of nanoparticles on the cell surface was observed by fluorescence microscopy and was found to be dependent on the stability of the linkages tethering nanoparticles to the cell surface.

Hydrogels were prepared by copolymerisation of Acrylamide with natural resources ; (1) Cane sugar juice (2) Sapodilla (chikoo- Manilkara zapota) extract (3) Pineapple( Ananas comosus) juice with the help of initiator [(Potassium Peroxydisulphate).(KPS-K2S2O8)]and using N,N'- Methylenebisacrylamide ( N,N-MBAAm) as crosslinking material in aqueous medium. Hydrogels of homopolymer of acrylamide and its copolymers with acrylic acid and methacrylic acid were also prepared for the purpose of comparision of results obtained. These hydrogels were characterised by FTIR ,SEM and XRD analysis . Swelling study of the above hydrogels were performed in aqueous media as a function of time. Stimuli response of pH of medium and temperature on swelling were also studied . Hydrogels were used for sorption study of hazardous metal ions [ Hg(II) , Pb(II) , Cd(II) ] as a function of Time , pH and temperature .

碩士
國立臺灣科技大學
纖維及高分子工程研究所
88
Abstract (Part Ⅰ) The study utilizes DSC to reveal the information about bound 、interface and free water in hydrogels made up of poly(vinyl alcohol) grafted with sodium styrenesulfonate (SSS).DSC thermograms for gels show two water melting peaks around 0℃, where the one at the lower temperature is attributed to the interfacial state, and another to the free water. The above two melting peaks come closer with the higher water content in gels and higher SSS grafting. Pulsed NMR gives the temperature dependence of spin-lattice relaxation time (T1) and spin-spin relaxation time(T2) .Both T1 and T2 decrease with water content in gels, and are below the T1 and T2 value of water, respectively. The activation energy of T1 in gels for total water and bound water are not equal , due to the influence exerted by interface water on the water motion. It is seen that the bound water plays a significant role in the hydration, and the relaxation times (T1 and T2) become longer with the crosslink density of gels. Abstract (Part Ⅱ) This study investigates the chitosan chemically crosslinked with the various proportion of glutaraldehyde in the acetic acid solutions, leading to the findings that the equilibrium water absorption drops with the crosslinker amount. DSC thermograms for the ice fusion around 0℃ show the fusion shoulders for the interface and free water, respectively, and these two peaks become distinguishable at high water content in gels. The higher crosslinking gives rise to a lower amount of bound water. The Pulsed NMR gives the spin-lattice relaxation time (T1) and spin-spin relaxation time(T2) , revealing the lower water-polymer interations in gels than water-water interactions the pure state. Further calcuation on the activation energy of bound water shows the same values as the total water, which indicates that the water interations and are completely controlled by the bound water or free water, with negligible influence by the interface water. This is maybe unstandable by the high amount of bound water binding to each monomer unit.

博士
大同大學
材料工程學系(所)
93
Stimuil-sensitive hydrogels change their physical properties in response to their surrounding environment such as pH, temperature and electrical potentials. Poly(N-isopropylacrylamide) (Poly(NIPAAm)) hydrogels in aqueous solution exhibits a rapid and reversible hydration-dehydration change in response to small temperature changes around its low critical solution temperature (LCST). Poly(NIPAAm) hydrogels have recently been of increasing interest in the field of controlled drug delivery, immobilization of enzymes, and artificial muscles. However, they have poor mechanical strength, especially after swelling, which limits their applications. Its can be improve by graft polymers onto surface of substrates. Poly(N-vinyl 2-pyrrolidone) (PVP) is widely used in medicine due to its high biocompatibility. In this study, itaconic acid (IA) was co-polymerized with N-vinyl 2-pyrrolidone (NVP) monomer to prepare the pH sensitive hydrogels. These copolymer hydrogels were prepared using ultra-violet (UV) induced methods at ambient temperature. Monomer and cross-linking agent (N, N’-methylene-bisacrylamide (MBAAm)) concentration effects on preparation of this copolymer hydrogel were investigated using swelling, FT-IR, and SEM. The prepared copolymer hydrogel is highly pH sensitive. The percentage swell of the copolymer hydrogels was found to increase from 150% to 3011% as the pH value of the swelling solution varied from 4 to 10. Hydroxyapatide (HAp)-contained hydrogel composite, analogous to bone structurally and biotical, will not only be easy to make desired shapes in workplace, but also have better mechanical strength to meet the requirements of bone substitute. The influences of polymerization and gel react factors on the characteristics of the fabriced composites hydrogel were investigated. The swelling ratios of composites hydrogel decreased from 16 to 10 as the ratio of HAp powder increased. The compressive strength of HAp/Poly(AAm/IA) composites hydrogel also increases from 7.0 (N/cm2) to 25.8 (N/cm2). HAp/Poly(AAm/IA) composites hydrogel with swelling capabilities in the range 800%~1000% were obtained. Modification of surface properties (such as wettability, electricity, adhesion and dyeing activity) of materials had become an important object to study, because they can maintain the bulk’s properties without any destruction. There are lots of modification methods such as acidic or alkaline treatment, plasma or corona exposure, polymer deposit or coating, metal vapor deposit or ion planting and additive blending. Among them, plasma polymerization is a fairly excellent method because it can produce the uniform activated surface and has low environmental pollution. In addition, using refined plasma equipment, the kinds of samples will not be restricted even if the samples are particles, fabric cloth, sheet or scaffold. However, the surface property of the plasma activating materials would decayed followed by the longer exposure in air due to the exhaust of activation sites. Therefore, in order to throughout change the surface property, subsequently UV light irradiated graft polymerization has been employed to form a stable and functional surface that had been proved to keep the surface properties for a long time. Another develop a novel method to formation of swelling and deswelling nonwoven PET/Poly(NIPAAm-co-different monomers) composite hydrogel by combined of surface graft and crossling polymerization reactions. The effect of change different monomer content of composite hydrogels on swelling/deswelling kinetics, and porous sizes will be investigated. The nonwoven PET/Poly (NIPAAm-co-NVP) composite hydrogels exhibit faster deswelling and reswelling rates. The hydrophobic surface of nonwoven poly(ethylene terephthalate) (PET) with surface inertia has limited the practical bio-applications. The objective of the present research was to surface graft polymerization of biocompatibility monomer onto plasma-treated nonwoven PET substrate utilizing ultra-violet (UV) induced methods. N-vinyl 2-pyrrolidone (NVP) was successfully grafted onto nonwoven PET surfaces. After the plasma activation and/or grafting, the hydrophobic surface of nonwoven was modified into a hydrophilic surface. Effects of various parameters such as monomer concentration, reaction time, initiator (ammonium peroxodisulfate (APS)) concentration and crosslinking agents (N, N’-methylene-bisacrylamide (MBAAm)) concentration on percentage grafting were studied. The grafting efficiency of the modified nonwoven PET surfaces reached maximum at 50 min UV irradiative time and 30wt% aqueous NPV solution. The surface wettability shows water absorption of NVP-grafted nonwoven PET (NVP-g-Nonwoven PET) increased with increasing grafting time. The NVP-g-Nonwoven PET was verified by FT-IR spectra and SEM measurements. The test of antibacterial assessment using Anti-Staphylococcus Aureus test indicated that the Staphylococcus Aureus has been restrained from growing in NVP-g-Nonwoven PET.

碩士
國立成功大學
化學工程學系
104
In this research, the preparation of dual stimuli-sensitive, biocompatible lipoic acid-modified poly(L-lysine) (PLL-g-Lipo) hydrogels/nanogels by chemical cross-link and polypeptide/silica hybrid hydrogels by depositing silica in the gel matrix. By ethylene oxide sterilization, hydrogels were prepared through the formation of inter-/intramolecular disulfide cross-link. Their mechanical properties and gelation were dictated by the amphiphilic nature and degree of inter-/intramolecular disulfide cross-link, which were influenced by the chain conformation. Upon changing the solution pH from neutral to acidic condition and/or cleaving disulfide bonds, these hydrogels showed redox- and pH-sensitive properties as demonstrated by the accelerated drug release. Silica deposition can stabilize the gel network and tune their mechanical properties as well as their payload release and colloidal properties.

Tese de Doutoramento em Ciências da Saúde
Spinal Cord Injury (SCI) is a highly debilitating condition, with devastating consequences for the patients and their families. Partial or complete loss of motor and sensorial functions below the level of injury are the main visible outcomes. However, cardiac and respiratory compromise, together with bladder and bowel dysfunctions, among others, are frequently observed, impairing significantly the quality of life. Currently there are no treatments for SCI, with most approaches being used in order to minimize injury progression. The lack of treatments can be attributed to the aggressive pathophysiology of SCI. The initial impact immediately leads to massive tissue damage and neuronal death, with edema formation and hemorrhages. For the next minutes up to several weeks, a cascade of cellular and molecular secondary alterations is triggered, leading to further neuronal damage. Finally, in the chronic phase, a glial scar and a cystic cavity are formed, creating a physical and chemical barrier to regeneration. Considering the injury complexity and the multitude of secondary alterations that can be targeted, it is more likely that a combinatorial therapeutic approach will have more impact than single-based therapies. Among the different approaches, tissue engineering (TE) and regenerative medicine concepts could be of extreme relevance for SCI. Cellular transplantation, one of the cornerstones of TE, has been applied in SCI research for decades. Nonetheless, and despite the numerous studies in the field, most of them fail when translated into the clinics. Combining biomaterial-based strategies with cell therapies could solve some of the associated problems, such as the low cell survival after transplants. In this way, the work developed during this thesis aimed to develop a combinatorial approach, conjugating the transplantation of two different cellular populations with a functional hydrogel, serving both as a physical matrix for neuronal regrowth and as a vehicle for cell transplantation. Thus, gellan gum hydrogel, previously modified with fibronectin-derived peptides (GGGRGDS), was combined with adipose tissue-derived stem/stromal cells (ASCs) and olfactory ensheathing cells (OECs). Both cell types have been associated with promising protective and regenerative effects, in different models of SCI. In this work, we firstly showed that ASCs and OECs could grow in vitro, in direct coculture systems, without affecting their morphology, growth and viability. In addition, their combination was beneficial in vitro, resulting in increased axonal growth using a model of axonal regeneration (Dorsal Root Ganglia – DRG – explants). Then, ASCs/OECs were applied as a single transplantation into a rat thoracic hemisection model of injury (T10 level). The treatment led to significant recovery of hindlimb function, which was associated with reduced levels of inflammation at the lesion site. Later, cells were encapsulated within GG-GRGDS hydrogels and demonstrated a normal morphology and growth in vitro. Moreover, their combined application into a lumbar hemisection model, led to a significant recovery of locomotor function. The histological analysis showed reduction in inflammation, astrogliosis and an increased number of neurofilament positive staining, possible indicative of axonal regeneration or neuronal protection. Finally, the same strategy was implemented in a cervical model of injury, which induces respiratory deficits, affecting diaphragmatic function. Following a C2 hemisection, hydrogel and cells were transplanted at the injury site, immediately after lesion. The combinatorial treatment induced the most significant recovery of diaphragmatic function, as assessed by electromyogram activity of the ipsilateral hemi-diaphragm. Both ventral and medial portions of the diaphragm were partially recovered. Moreover, and despite no differences were seen in forelimb motor function, GG-GRGDS and ASCs/OECs induced a significant recovery of sensorial perception, in the contralateral forelimb, as measured by the Von Frey test. All together, these results disclose a great therapeutic potential for the application of GGGRGDS hydrogels with ASCs and OECs, since its application to different models of injury resulted in significant and relevant improvements of function. Not only motor behaviors associated with locomotion were recovered, but also motor control of the diaphragm, essential for respiration, and also sensorial perception recovery. In addition, all components of this approach could be translated to the clinics, as ASCs and OECs can be obtained from autologous sources and gellan gum proved to be biocompatible, with low immunogenic potential. This work presents an important strategy for SCI repair, that with further pre-clinical testing in larger animal models, could be one day applied to the clinics.
As lesões vertebro-medulares (LVM) são uma condição debilitante, com consequências devastadoras quer para pacientes como para as suas famílias. A perda parcial ou total das capacidades motoras e sensoriais abaixo do local da lesão é a consequência mais notória. Contudo, problemas cardíacos e respiratórios, assim como disfunção dos sistemas urinário e gastrointestinal, entre outros, acontecem frequentemente, reduzindo significativamente a qualidade de vida. Atualmente não existem tratamentos para as LVM, com a maioria das abordagens a ser utilizada apenas de modo a minimizar a progressão da lesão. A falta de tratamentos pode ser atribuída à agressiva fisiopatologia da doença. O impacto inicial leva a um dano tecidular e morte neuronal imediatas, com formação de edema e hemorragia. Durante os minutos seguintes, até várias semanas, uma série de alterações celulares e moleculares é ativada, conduzindo a um aumento do dano neuronal. Por fim, na fase crónica, são formadas a cicatriz glial e a cavidade cística, criando uma barreira física e química à regeneração. Tendo em conta a complexidade e a panóplia de alterações secundárias que podem ser usadas como alvo terapêutico, é provável que tratamentos baseados em abordagens combinatórias terão um maior impacto do que estratégias singulares. Dentro das várias possibilidades, os conceitos usados em engenharia de tecidos e medicina regenerativa poderão ser de uma grande relevância para as LVM. O transplante celular é um dos pilares da engenharia de tecidos e tem vindo a ser aplicado na investigação em LVM desde há décadas. Não obstante, e apesar do elevado número de trabalhos neste campo, a grande maioria falha quando tenta ser aplicado na clínica. Combinar estratégias baseadas em biomateriais com terapias celulares poderá resolver alguns dos problemas associados a esta abordagem, nomeadamente a baixa sobrevivência das células após transplante. Deste modo, o trabalho desenvolvido durante esta tese teve como objetivo desenhar uma abordagem combinatória, conjugando o transplante de duas populações celulares distintas com um hidrogel modificado, que serve tanto como uma matriz física para o crescimento neuronal, assim como um veículo para o transplante celular. Neste sentido, o hidrogel goma gelana, previamente modificado com péptidos derivados de fibronectina (GG-GRGDS), foi combinado com células estaminais do tecido adiposo (ASCs) e células envolventes do bolbo olfativo (OECs). Ambos os tipos celulares têm sido associados a efeitos neuro-protetores e neuro-regenerativos, em diferentes modelos de LVM. Neste trabalho, primeiramente demonstramos que ASCs e OECs crescem in vitro, em sistemas de co-cultura direta, sem que sejam afetadas as suas morfologias, proliferação e viabilidade. Para além disso, a sua combinação foi benéfica, levando a um crescimento de neurites, num modelo in vitro de regeneração axonal. De seguida, ASCs/OECs foram transplantadas para um modelo de rato de hemisecção torácica (nível T10). O tratamento induziu uma recuperação significativa da função das patas traseiras, o que esteve associado a níveis reduzidos de inflamação no local da lesão. Mais tarde, as células foram também encapsuladas em hidrogéis de GG-GRGDS e apresentaram uma morfologia e crescimento normais in vitro. Adicionalmente, a sua aplicação conjunta num modelo de hemisecção lombar (mais agressivo) levou a uma melhoria significativa da locomoção. A análise histológica permitiu perceber uma redução da inflamação, da astrogliose e aumento da marcação para neurofilamento, possível indicador de regeneração axonal ou de maior proteção neuronal. Por fim, a mesma estratégia foi implementada num modelo de lesão cervical, que induz défices respiratórios, afetando a função do diafragma. Após hemisecção em C2, hidrogel e células foram imediatamente transplantados, no local de lesão. O tratamento combinado levou a uma maior recuperação da função do diafragma, avaliada por eletromiograma do músculo ipsilateral do diafragma. As regiões mais dorsal e medial do diafragma demonstraram uma recuperação parcial da função. Apesar de não terem sido observadas diferenças na função motora das patas dianteiras, a terapia combinatória ajudou a recuperar a função sensorial, da pata dianteira contralateral, após avaliação com filamentos de Von Frey. Resumindo, estes resultados revelam um grande potencial terapêutico para o uso de hidrogéis de GG-GRGDS com ASCs e OECs, dada a sua aplicação com sucesso a diferentes modelos de lesão, com melhorias de função significativas. Não só comportamentos como a locomoção foram melhorados, mas também o controlo do diafragma foi recuperado parcialmente, o que é essencial para a função respiratória, e ainda a perceção sensorial. Mais ainda, todas as componentes desta abordagem podem ser facilmente aplicadas na clínica, visto ser possível obter ASCs e OECs de uma maneira autóloga (do próprio paciente) e ao facto da goma gelana ser biocompatível, com baixa probabilidade de provocar uma reação imune. Este trabalho apresenta uma abordagem relevante para as LVM, que após mais estudos pré-clínicos em animais de maior porte, poderá um dia vir a ser aplicado em pacientes.
The work presented in this thesis was performed in the Life and Health Sciences Research Institute (ICVS), athe Schol of Medicine, University of Minho. Financial suport was provided by Prémios Santa Casa Neurociências - Prize Melo e Castro for Spinal Cord Injury Research (MC-17-2013 and MC-04-2017); Portuguese Foundation for Science and Technology (Doctoral felowship to Eduardo Gomes SFRH/BD/103075/2014, Post-doctoral to Nuno Silva BPD/9701/2013, IF Development Granto A. J. Salgado). This thesis was performed under the Memorandum of understanding on Academic exchanges betwen Schol of Medicine, University of Minho and the Luso-American Development Foundation. This thesis was also funded by national funds through FCT under the scope grant reference TUBITAK/07/2014 and 359-PCDT Project: PTDC/DTP-FTO/5109/2014. Suport was also provided by: Craig H. Neilsen Foundation (grant #47686 to A.C. Lepore) and the National Institute of Neurological Disorders and Stroke (#2R01NS079702; 1R01NS10385; #1R56NS096028 to A.C. Lepore). This thesis has been developed under the scope of the projects NORTE-01-0145-FEDER-013, suported by Northern Portugal Regional Operational Programe (NORTE 2020), under the 2020 Partnership Agrement, through the European Development Fund (FEDER). This work has ben funded by FEDER funds, through the Competitivenes Factors Operational Programe (COMPETE), and by National funds, through the Foundation for Science Technology (FCT), under scope of the project POCI-01-0145- FEDER-07038. ASCs were kindly provided by Prof. Jef Gimble (LaCel Inc, USA).

Dissertação de Mestrado Integrado em Engenharia Química apresentada à Faculdade de Ciências e Tecnologia
Nowadays, bone infections due to diseases or injuries are a major problem, and the existing methods to treat them present some gaps and have several associated problems. In the case of auto and allografts, the mains problems are lack of donors and the risk of infections. While, in the case of implants and bone substitutes, the rejection is the main obstacle. The field of Tissue Engineering presents alternatives, such as scaffolds, to promote regeneration of injured tissues. Despite the advantages of these materials, most of them have an invasive surgical procedure associated. In order to avoid these problems, the main focus of this thesis is the development of scaffolds for bone regeneration, in the form of injectable hydrogels, which allow the regeneration of bone as they degrade and do not involve invasive procedures. Throughout this work, injectable hydrogels will be developed based on two natural polymers, dextran and gelatin, along with the use of two inorganic compounds, calcium β-triphosphate and nanohydroxyapatite, to reinforce the mechanical properties. In order to understand the influence of some parameters on formulation, different compositions were tested, varying the amount of crosslinker and the presence of inorganic compounds in the polymeric matrix. The developed material was later characterized to evaluate the necessary requirements for the intended application. FTIR and NMR analysis were performed to chemically characterize the material and to verify the chemical modification of the polymers. Taking into account the requirements for the intended application, the swelling capacity of the material was evaluated, as well as its degradation in a simulated physiological environment. To evaluate the influence of the different composition materials in mechanical properties, compression tests were performed. Vancomycin was incorporated into the polymeric matrix to assist the regeneration process, and the drug release profile was evaluated. The biocompatibility of the material was evaluated through MTS assay, using osteoblasts. The results showed that the synthesis of dextran-based hydrogels was successful, unlike gelatin-based hydrogels. In general, the hydrogels presented a suitable degradability, about one month, which are in line with the average time of the bone regeneration process. The compression tests gave favourable values for Young’s modulus (200-300 kPa), however they showed come variability due to the geometry of the sample used in the analysis. The drug release profile showed an initial burst release of around 50-80%, which makes longstanding treatment difficult, but it can facilitate the prevention of infections in the initial period. Regarding the material’s biocompatible, the results obtained showed some cytotoxicity which could be associated with AAD.
As infeções ósseas derivadas de doenças ou de lesões constituem um problema na atualidade, e os métodos para as tratar têm algumas lacunas e alguns problemas relacionados. No caso dos auto e aloenxertos, os principais problemas são a falta de dadores e o risco de infeções. Enquanto que no caso dos implantes e substitutos ósseos, a rejeição é o principal obstáculo. O campo da Engenharia de Tecidos apresenta alternativas, como scaffolds com vista a promover a regeneração dos tecidos lesionados. Apesar das vantagens destes materiais, a maioria deles têm associado um procedimento cirúrgico invasivo. De modo a contornar estas questões, o principal foco da presente dissertação é o desenvolvimento de scaffolds para regeneração óssea, sob a forma de hidrogéis injetáveis, que possibilitem a regeneração do tecido ósseo à medida que se degradam, e que não envolvam procedimentos invasivos. Ao longo deste trabalho serão desenvolvidos hidrogéis injetáveis a partir de dois materiais de base natural, o dextrano e a gelatina, e ainda a utilização de dois compostos inorgânicos, β-trifosfato de cálcio e nano hidroxiapatite, para reforço das propriedades mecânicas. De modo a compreender a influência de alguns parâmetros na formulação, serão testadas várias composições variando a quantidade de reticulante e a presença de inorgânicos na matriz polimérica. Para compreender se o material desenvolvido apresenta as características necessárias para a aplicação em vista, este foi submetido a métodos de caracterização. Foram realizadas análises de FTIR (Infravermelho por Transformada de Fourier) e RMN (Ressonância Magnética Nuclear) para caracterizar quimicamente o hidrogel e para verificar a modificação química dos polímeros. Tendo em conta os requisitos para a aplicação em vista, foi avaliada a capacidade de inchaço do hidrogel, assim como a sua degradação em ambiente fisiológico simulado. De modo a auxiliar o processo de regeneração, foi incorporada Vancomicina na matriz polimérica e posterior avaliação do perfil de libertação da mesma. A biocompatibilidade do material foi avaliada através do teste MTS ((3-(4,5-dimethylthiazol-2-yl)-5-(3-carboxymethoxyphenyl)-2-(4-sulfophenyl)-2H-tetrazolium), com osteoblastos. Por fim, para avaliar a influência das várias composições do material nas propriedades mecânicas, foram realizados testes de compressão.Os resultados obtidos mostraram que a síntese de hidrogéis à base de dextrano foi bem sucedida, ao contrário dos hidrogéis à base de gelatina. De modo geral, os hidrogéis obtidos apresentaram uma degradabilidade adequada, cerca de um mês, o que coincide com o tempo médio do processo de regeneração óssea. Os testes de compressão originaram valores favoráveis para o módulo de Young (200-300 kPa), contudo apresentaram alguma variabilidade devido à geometria da amostra. Nos testes de libertação obteve-se um perfil com um burst inicial entre 50 e 80% do fármaco, o que dificulta um tratamento prolongado, mas pode facilitar a prevenção de infeções no período inicial. Relativamente à biocompatibilidade do material, os resultados mostraram alguma citotoxicidade, o que sugere que tal seja devido à influência do AAD.

碩士
中華科技大學
健康科技研究所在職專班
105
Acrylic acid was grafted to ozone treated alginate/polyvinyl alcohol (Alg/PVA) hydrogels. The resulting hydrogels were further grafted with chitosan (CS) via esterification. Afterward CS-grafted hydrogels were immobilized with hyaluronic acid (HA). The resulting Alg/PVA-HA hydrogels were characterized including the blood compatibility, the biocompatibility, and the cytotoxicity. These properties were employed to evaluate the applicability in biomedical areas. Surface properties of modified Alg/PVA-HA hydrogels could be detected by X-Ray Photoelectron Sprectroscpoe (XPS) and dyeing. The effect of the positive charges of CS-grafted material on the absorption of negatively charged proteins of human serum albumin (HSA) and human plasma fibrinogen (HPF) was be studied. After grafting CS, the interaction between the membrane surface and the negatively charged proteins were electrostatic attraction. Thus the amount of adsorption/attachment increased with the surface positive charges on the hydrogels. One the other hand, the hydrogels immobilized with hyaluronic acid could decreased the amount of adsorption/attachment proteins. In addition, the in vitro cytotoxicity test results from culturing L929 fibroblasts show that these modified Alg/PVA-HA hydrogels were not cytotoxic.

碩士
雲林科技大學
化學工程與材料工程研究所
98
Hydrogen adsorption was investigated on the super activated carbon (AC) prepared by litchi wood, activated by potassium hydroxide under N2 atmosphere. The AC texture characteristics were determined by using X-ray diffractometer analysis, transmission electron microscope and nitrogen adsorption analysis. The physical and chemical properties of the AC before and after modification were determined by X-ray photoelectron spectroscope and atomic absorption spectrometer. Hydrogen capacity of the AC was obtained by a volumetric adsorption apparatus. The prepared-activated carbon was immersed by ammonia or nitric acid to modify its surface functional groups. The modified AC was also decorated by cobalt and palladium individually. The effects of various surface functional groups with metal on hydrogen capacity were investigated. In addition, the hydrogen adsorption on the graphene sheets was also determined. The effect of hydrogen spillover on the hydrogen uptake on the bridged metal-activated carbon was also discussed. Experimental results showed that activated carbon decorated by palladium or cobalt, have a positive enhancement for hydrogen storage. In addition, from XPS spectra, nitrogen functional groups on the surface of AC modified by ammonia were increased. The nitrogen functionality on the AC is favorable for hydrogen adsorption. The effect of hydrogen spillover of cobalt decorated ammonia modified AC was observed. For acidic modification, hydrogen storage capacity decreased along with the increase of the oxygen-containing functional groups on the AC. The effect of hydrogen spillover of metal decorated nitric acid modified AC was insignificant on the hydrogen adsorption capacity. Furthermore, the hydrogen capacity of the modified graphene showed irregularity. The graphene decorated by platinum and palladium showed the hydrogen adsorption capacity enhanced from 0.067 wt.% to 0.15 wt.% and 0.156 wt.%, respectively, that is, the enhancement factors were 1.23 and 1.33.

碩士
國立成功大學
材料科學及工程學系碩博士班
94
In this study, chitosan was prepared in a form of hydrogel bead and of thin film using tripolyphosphate and sodium hydroxide as the cross-linking agent. The as-prepared chitosan hydrogel beads and films were then frozen and dried. Beads with a rough diameter of 3 mm and films with a thickness of 2 mm were thereafter obtained. The dried chitosan beads and films were furthermore modified by either argon or ammonia plasma. New chemical structures on the plasma-modified chitosan film were measured using XPS (X-ray Photoelectron Spectroscopy). The low concentration copper or nickel-ions containing solution was used for the evaluation of beads’ adsorption characteristic and analyzed by ICP-MS (Inductively Coupled Plasma/Mass Spectroscopy). Desorption rate of the post-adsorption beads was conducted in 1 M sulfuric acid, while the change of low concentration metal ions was also analyzed by ICP-MS. The adsorption-desorption effect of the plasma-modified chitosan-containing beads was thereafter discussed. Experimental results exhibited that the formation of hydrogel beads was completed within short preparation time using 2% chitosan-acetic acid solution in 2 g of tripolyphosphate and 2 g of sodium hydroxide. The as-prepared chitosan hydrogel beads were capable to adsorb more copper ions, in comparison with nickel ions. At the same time, the adsorption capacity exhibited higher at the pH value of 5.1 than that of 2.1, while ammonia plasma treatment is much efficient than argon plasma treatment on the adsorption rate of the plasma-modified chitosan hydrogel beads. From XPS, metallic species could be found on the chitosan hydrogel film at the binding energies of 933.1 eV for the copper-N bond and 852.5 eV for the nickel-N bond, which showed the presence of metal ions on chitosan. The N/C ratio increased 10% after 10 sec of ammonia plasma treatment. The increase of nitrogen content on the ammonia plasma treated chitosan resulted in the increase of ion adsorption rate. Desotpion rate of the ion-containing samples was capable to reach 60% by adding 1 M sulfuric acid.