Orientador: : Leonardo Fernandes Fraceto / Dissertação (mestrado) - Universidade Estadual de Campinas, Instituto de Biologia / Made available in DSpace on 2018-08-23T08:25:53Z (GMT). No. of bitstreams: 1 Pereira_AndersondoEspiritoSanto_M.pdf: 3153536 bytes, checksum: 2427b9dc08e349cd1eadf5c8a001ceb9 (MD5) Previous issue date: 2013 / Resumo: A "Revolução Verde" ocorreu na década de 60 e previa o aumento da produção agrícola devido ao crescimento populacional, onde foi intensificado o estudo de novas tecnologias para o aumento da produção de alimentos e rentabilidade dos agricultores. Entre as várias tecnologias, destacou-se a utilização de defensivos agrícolas no controle, prevenção e na eliminação de doenças que interferem na produtividade agrícola. O uso de nanopartículas (NPs) para o carreamento de compostos bioativos para liberação sustentada aumenta o tempo de ação e estabilidade química do ativo no meio, bem como a disponibilidade para ação junto ao organismo alvo. Na agricultura, o uso de NPs visa reduzir a concentração efetiva do ativo a ser utilizado, reduzir de aplicações, reduzir a toxicidade, diminuir a periculosidade e os riscos de contaminação ambiental. O presente trabalho propôs o desenvolvimento de NPs poliméricas de poli-épsilon caprolactona (PCL) como sis-temas carreadores para o herbicida atrazina (ATZ) bem como a avaliação das características físico-químicas destes sistemas, a atividade herbicida e a genotoxicidade das formulações preparadas. As nanocápsulas (NCs/ATZ) e as nanoesferas (NEs/ATZ) contendo ATZ apresentaram diâmetro médio de 483,1 ± 10,4 nm e 408,5 ± 2,5 nm, respectivamente. A ATZ apresentou uma eficiência de encapsulação acima de 90% para as formulações de NE e NC e foram observadas alterações no perfil de liberação da ATZ em comparação com o herbicida ATZ. A estabilidade coloidal e físico-química das formulações foi mantida por um período de 90 dias. O uso de NPs aumentou a retenção da ATZ em ensaios com coluna de solo, sendo que a atividade herbicida se mostrou mais eficaz quando comparada ao ativo ATZ apenas e ao de uma formulação comercial (Gesaprin). A investigação da genotoxicidade das formulações, utilizando o ensaio de aberração cromossômica Allium cepa, mostrou que a encapsulação da ATZ reduziu os efeitos sobre o número de aberrações cromossômicas quando comparadas ao ativo ATZ e à formulação comercial. As formulações de NPs contendo ATZ preparadas neste trabalho apresentam grande potencial para aplicação na agricultura, uma vez que estas podem ter ação herbicida utilizando menor concentração de ativo, reduzem a mobilidade da ATZ no solo e diminuem os efeitos genotóxicos, tornando-se mais seguras ao meio ambiente e reduzindo os riscos de contaminação / Abstract: The "Green Revolution" occurred during the decade of 60 and it aimed towards the rapid increase on agriculture production due to population growth, when was intensified the research and development to increase agriculture production and profitability. Among several technologies, herbicides and pesticides have emerged to control, prevent and destroy diseases that interfere in the agricultural productivity. The use of nanoparticles (NPs), as drug delivery system loads to modified drug release profile, increase time of action and increased chemical stability is wells is increase in bioavailability. In agriculture the use of NPs can reduces the amount of chemical used and the number of applications with decrease in toxicity, minimizing the risks of an environmental contamination. This study aims to develop NPs pre-pared with poly-épsilon-caprolactone (PCL) as a carrier system for the herbicide atrazine (ATZ). The formulations were characterized and the herbicide activity and genotoxicity were investigated. The nanocapsules (NCs/ATZ) and nanospheres (NE/ATZ) containing ATZ showed a size average diameter of 483.1±10.4 nm and 408.5±2.5 nm respectively. The ATZ presented encapsulation efficiency over 90% on formulations of NC and NE. The release profiles of the ATZ encapsulated in NPs were changed in relation to the ATZ herbicide only. The colloidal stability over 90 days showed that the formulations were stable. The use of NPs increased the retention of ATZ on soil column and showing that the herbicide was more active when compared to ATZ or a commercial formulation (Gesaprin). The genotoxicity evaluation showed that the encapsulation of ATZ reduced the toxic effects on the number of chromosomal aberration when compared to active ATZ and commercial formulation. NPs formulation containing ATZ prepared in this study presented a great potential for application in agriculture, since these formulations have the same herbicide activity (using lower concentration of active compound), reduce the ATZ soil mobility and also decrease the genotoxicity effects of ATZ, and in this way, reducing the risks of environmental contamination / Mestrado / Bioquimica / Mestre em Biologia Funcional e Molecular

Orientadores: Lucia Helena Innocentini Mei, Marcos Akira dÁvila / Dissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Engenharia Química / Made available in DSpace on 2018-08-19T17:34:43Z (GMT). No. of bitstreams: 1 Nista_SilviaVazGuerra_M.pdf: 12755531 bytes, checksum: ed049fb5fccf4416e7f0b8a0290222af (MD5) Previous issue date: 2012 / Resumo: Este projeto foi desenvolvido em duas fases, usando a tecnologia de eletrofiação. A primeira fase foi dedicada a obtenção de membranas eletrofiadas com acetato de celulose, as quais formaram nanofibras que foram carregadas com Sulfato de gentamicina, na segunda fase, para estudos da liberação controlada deste fármaco. Na primeira fase as membranas de nanofibras de Acetato de Celulose, chamadas de nanomembranas, foram produzidas utilizando-se quatro misturas de solventes (Acido Acético/Água (75:25 m/m), Acetona/Água (85:15 m/m), Dimetilacetamida (DMAc)/Acetona (1:2 m/m), Dimetilacetamida/Acetona/Água (32/63/5 m/m)). Usando a ferramenta de planejamento de experimentos (DOE), foram definidos os melhores parâmetros para preparação das membranas nanoestruturadas, em cada sistema de solvente. Três variáveis, sendo a distância entre a agulha e o coletor, a concentração de acetato de celulose na solução e a tensão aplicada, em dois níveis (alto e baixo), foram estudadas em cada sistema. As respostas avaliadas para obtenção da melhor condição, em cada caso, foram o diâmetro médio da fibra obtida e aspecto da membrana formada. Foi realizado também, no sistema de solvente Acido Acético/Água (70:30 m/m), um comparativo entre fiação horizontal, utilizando-se uma taxa de alimentação controlada por uma bomba de infusão, e um sistema vertical onde o fluxo era governado pela gravidade e viscosidade da solução. Um estudo da influencia da taxa de alimentação no diâmetro e aspecto da membrana também foi realizado. Todas as soluções foram avaliadas quanto a sua viscosidade, tensão superficial e condutividade elétrica. Nas soluções de cada sistema de solvente, que apresentaram a melhor condição de processabilidade e melhor membrana, foi realizada uma avaliação do comportamento reológico com a construção de uma curva de Viscosidade versus Taxa de cisalhamento. As melhores membranas obtidas para cada sistema de solvente foram submetidas a um teste de Citotoxicidade para confirmar a biocompatibilidade e sua independência com os resíduos dos solventes utilizados. Na segunda fase utilizaram-se as melhores condições obtidas para cada sistema de solvente e incorporou-se o fármaco Sulfato de Gentamicina em duas concentrações 6 e 60% em massa com base no acetato de celulose. Observou-se a influencia da concentração do fármaco no processo de eletrofiação, no aspecto da membrana formada bem como no diâmetro da nanofibra obtida. A melhor membrana obtida nesta etapa foi produzida a partir do sistema de solventes DMAc/Acetona/Água. As condições de processo utilizadas foram 1 ml/h de vazão, 10 cm de distância entre agulha-coletor e 15 kV de tensão e concentração de acetato de celulose de 15%. Este sistema apresentou-se como um processo bastante viável, não havendo alteração na qualidade da membrana e no processo com a variação da concentração do fármaco. À membrana obtida nestas condições, foi adicionado 50% do fármaco e realizado um teste de liberação com o objetivo de verificar o perfil de liberação do mesmo. Foi realizado um comparativo entre o perfil de liberação desta membrana com o de outras membranas preparadas por casting e com recobrimento de HPMC, Eudragit® L100 e nanofibra eletrofiada de acetato de celulose. O melhor perfil obtido, onde ocorreu uma redução no efeito burst, foi com a membrana revestida com nanofibra, onde foi obtido um ganho de liberação de 9 horas em relação às demais. A melhor membrana obtida também foi submetida a uma análise microbiológica, onde se verificou que o fármaco não perdeu suas propriedades com o processo de eletrofiação / Abstract: This project was developed in two phases, using the technology of electrospinning. The first phase was devoted to obtaining electrospun membranes with cellulose acetate, which formed nanofibers that were loaded with Gentamicin sulphate, in the second phase, for the studies of this drug release. In the first step, these membranes were composed of electrospun nanofibers made of cellulose acetate, here called nanomembranes, using four solvents mixtures (acetic acid/water (75:25 w/w) acetone/water (85:15 w/w), dimethylacetamide(DMAC)/acetone (1:2 w/w), DMAc/acetone/water (32/63/5 w/w). Using the tool for design of experiment (DOE), the best parameters for preparation of nanostructured membranes in each solvent system were fixed. Three variables, such as the distance between the needle and the collector, the concentration of cellulose acetate in solution and the applied voltage, in two levels (high and low), were used in each system. The responses evaluated to obtain the best condition, in each case, were the average diameter of the fiber obtained and the aspect of the membrane formed. In the solvent system formed by acetic acid/water (70:30 w/w), a comparison was carried out between horizontal electrospinning, using an infusion pump to control the feed rate, and a vertical system, whose flow was governed by both gravity and viscosity of the solution. A study of the influence of feed rate on the diameter and aspect of the membranes was done. The viscosity, surface tension and electrical conductivity of all solutions were evaluated. For each system of solvent used, the best parameters of processing ant the best membrane aspect obtained were the chosen for the studies of the rheological behavior of the system by plotting a curve of Viscosity versus Shear rate. The best membranes obtained, for each mixture of solvent used, were submitted to a cytotoxicity test to confirm their biocompatibility and if the residues of any solvent could influence on this test. In the second step of the project, the best conditions obtained for each solvent system were used to electrospun the membranes loaded with gentamicin sulfate in two concentrations, i.e. 6 and 60 wt%, based on cellulose acetate. We observed the influence of the drug concentration in the electrospinning process, as well as the aspect of the membrane formed and the diameters of the nanofibers formed. The best membranes obtained in this step were produced using the solvent system DMAC/acetone/water. The process conditions used were 1 ml/h flow rate, 10 cm distance between needle-collector, 15 kV voltage and 15% cellulose acetate concentration in the solution. This system proved to be a quite feasible process, with no change in the membrane aspect or in the process, for several drug's concentration. To the membrane obtained in these conditions, 50% of the drug was added and the profile of its delivery was observed. A comparison of the releasing profile was also done among this membrane and other membranes prepared by casting and by coating with HPMC, Eudragit ® L100 and electrospun nanofibers of cellulose acetate. The best delivery profile obtained was the membrane coated with nanofiber of acetate solution in DMAC/acetone/water since there was a reduction in the burst effect and a gain in the releasing of 9 hours over the others. The best membrane obtained was also submitted to a microbiological analysis, in which it was verified that the drug did not lose its function during the electrospinning process / Mestrado / Ciencia e Tecnologia de Materiais / Mestre em Engenharia Química

Over the past few decades many researchers have investigated the utility of in vitro - in vivo correlations for the assessment of dosage forms. These investigations are, however, dependent on reproducible dissolution data and well conducted biostudies in order to establish meaningful and robust correlations. Despite the fact that the establishment of such correlations is perhaps idealistic, considerable interest has still been shown in this area of research. Various Controlled/Modified Release Dosage Forms (CMRD's) of theophylline, a weakly basic drug, and indomethacin, a weakly acidic drug, were assessed in order to establish in vitro - in vivo correlations. Dissolution rate studies were carried out using either the USP basket or paddle apparatus. The dissolution rate studies were conducted in a range of dissolution media of varying pH. Bioavailability studies were conducted on the dosage forms used by the Biopharmaceutics Research Institute at Rhodes University. The results of these biostudies were kindly made available for use in this research project. Type A correlations were established using a mathematical simulation process whereby expected in vivo responses are simulated and compared to actual profiles obtained for the dosage forms. In order to perform the simulations the dissolution rate profiles were stripped and using linear regression and the methods of residuals the dissolution rate order and the relevant dissolution rates were obtained. The results of the s imulations indicated that the in vivo serum concentration-time curves could be accurately predicted for the theophylline dosage forms but to a lesser extent, for the indomethacin formulations. The dissolution rate studies indicated that the paddle method is a suitable method for dissolution rate studies of theophylline CMRD's, although it appeared that the optimum pH of the dissolution medium was formulation dependent. Dissolution rate studies conducted on indomethacin formulations indicated that the USP specified basket method for extended-release indomethacin formulations was not able to distinguish between two formulations which exhibited different in vivo profiles. The conversion to the paddle method was, however, able to highlight the differences between these formulations. The use of three dimensional topographs to depict dissolution rate profiles was demonstrated for formulations of both theophylline and indomethacin. The topographs enabled the successful differentiation between bioinequivalent formulations. The dissolution rate profiles were also fitted to the Wei bull equation and the parameters obtained from this were compared to the Weibull parameters obtained from the in vivo absorption plots obtained using the Wagner-Nelson method. The results indicated that the Weibull function was suitable to describe both the in vivo and in vitro data. The following recommendations for the preformulation dissolution studies of weakly acidic and weakly basic drugs are proposed. The dissolution rate studies of weakly acid drugs, such as indomethacin, should be carried out over a range of pH utilising the paddle apparatus. Three dimensional topographs based on the dissolution data should be constructed and used as a comparative tool for different formulations. Based on these comparisons the appropriate formulation can then be selected for a pilot scale in vivo bioavailability study. The dissolution rate studies of weakly basic drugs, such as theophylline, should be carried out over a range of pH utilising the paddle apparatus. The dissolution data should then be used to simulate the expected in vivo profile and on this basis the appropriate formulation selected for a pilot scale bioavailability study. The above approach to the preformulation studies of new CMRO's would allow for the more careful selection of new dosage forms and could thus eliminate costly and unnecessary bioavailability studies performed on inferior formulations.

archives@tulane.edu / 1 / Olakunle Francis Ojo

Repellents play a key role in preventing mosquito-borne diseases such as malaria by reducing human-vector contact. The general mechanism of action relies on providing a repelling vapour around the applied area on the skin. Thus, the proper evaporation rate and consistency of the composition of the released vapour are factors determining the performance of repellent formulations. The formulation should evaporate fast enough to provide a sufficient level of repellence during its life time. However, if evaporation proceeds too fast, then it will be depleted rapidly so that activity is lost within a short period of time, which makes the repellent inefficient. Several controlled-release approaches have been developed to improve both the protection time and level. However, these techniques have inherent drawbacks from the industrial point of view. Moreover, these techniques mostly focus only on reducing the release rate, while the consistency of the vapour composition has not been addressed. In the present study, a novel approach towards controlling the evaporation behaviour of repellents is proposed. It is based on engineering the molecular interactions in order to design negative pseudo-azeotrope formulations. Negative pseudo-azeotrope mixtures are less volatile than the pure parent components and they do not undergo separation during evaporation. The feasibility of the idea was investigated by studying the molecular structure of generally available repellents. Among known molecular interactions, hydrogen bonding has the most likely impact on the formation of azeotropes and in particular pseudo-azeotropes. Thus, established repellents were classified based on their chemical structures and their capability to take part in hydrogen bonding. Next, a simple spectroscopic method for anticipating pseudoazeotropes formation was developed. Binary compositions of nonanoic acid and ethyl butylacetylaminopropionate (IR3535) showed a potential for forming pseudo-azeotrope mixtures. Hence R3535 and nonanoic acid were selected as model compounds to test the hypothesis. An experimental technique to confirm pseudo-azeotrope formation and to locate the composition of the probable pseudo-azeotrope point was required. To this end, an oven test was designed. The temporal mass loss, under an isothermal program, of a series of evaporating mixtures was measured. Simultaneously, the Fourier transform infrared (FTIR) spectra of the liquid remaining was recorded. Inverse analysis techniques were used to determine the composition of remaining liquid mixtures from the recorded FTIR spectra. The oven tests revealed that, as vaporisation progressed, the composition of the liquid remaining and the emitted vapour converged to a fixed IR3535 content of ca. 75 mol%. Mixtures close to this composition also featured the lowest volatility. Oven test also showed that the composition of the liquid mixtures diverged from the fixed IR3535 content of ca. 10 mol%. Mixtures close to this composition featured the highest volatility. These observations showed that IR3535 and nonanoic acid forms two pseudo-azeotrope compositions, i.e. a negative pseudo-azeotrope at an IR3535 content of ca. 75 mol%, and a positive pseudo-azeotrope at IR3535 content of ca. 10 mol%. Thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC) were applied to check these results. TGA confirmed that the negative pseudo-azeotrope mixture is less volatile while the positive pseudo-azeotrope is more volatile than the parent compounds. The DSC results revealed that in comparison with the pure compounds, negative pseudo-azeotrope had a lower boiling point onset while the positive pseudo-azeotrope had a higher boiling point. Although negative pseudo-azeotrope repellent formulations have the desired lower constant release rate, their repellent activity needed to be tested. This is due to the fact that mixing the ingredients to formulate a negative pseudo-azeotrope results in interactions among the components. As a consequence, the inherent repellence effect of the compounds might have been impaired in the mixture. The modified arm-in-cage test was used to test the repellence of the controlled-release repellent formulation i.e. the negative pseudo-azeotrope of the IR3535 + nonanoic acid system. Results showed that the mixture featured improved performance with respect to both repellence efficacy and persistence. Moreover, the negative pseudo-azeotrope also exhibited a knock down effect, even resulting in mortality of most of the test mosquitoes. The presence of two pseudo-azeotrope points at different composition in the IR3535 + nonanoic acid system is a rare occurrence, analogous to double azeotropy. Thus, molecular simulation techniques were used to explore the nature of system and the interactions responsible for this unique behaviour. Gibbs-Monte Carlo simulation results suggest that variations in the sizes of the molecular clusters present in the liquid at various compositions might be responsible. They revealed that IR3535 and nonanoic acid in neat form are both highly structured liquids. The break-down in the structure of IR3535 at high concentrations of the acid may be the origin of increased evaporation rate and formation of the positive pseudo-azeotrope. On the other hand, negative pseudo-azeotrope may be resulted from formation of bulkier clusters at the ration of 3:1 (IR3535: nonanoic acid). / Thesis (PhD (Chemical Technology))--University of Pretoria, 2016. / English / PhD (Chemical Technology) / Unrestricted

In this study, lanolin alcohol as well as lanolin alcohol-povidone films (1:1 . 5) were investigated as a potential drug delivery system. The in vitro drug release from these films was studied in terms of the effect of agitation, film thickness and drug concentration. The rate of release of Cortisol from lanolin alcohol films was not affected by the intensity of agitation. Moreover, the film matrix was found to remain essentially intact throughout the release process. Further analysis of the data revealed that Higuchi's diffusion-controlled granular matrix model explained the mechanism of Cortisol release from such films. The results of drug release from lanolin alcohol povidone films have shown that although Higuchi's release rate constant was found to be independent of film thickness, it was affected by the intensity of agitation, since the rate constant was found to increase as agitation speed was increased, especially at low speeds. In addition, povidone was found to leach out of the film matrix along with the drug. These factors, in conjunction with further analysis of the drug, explained the failure of this film system to conform to the matrix-controlled diffusion model. The release rate of Cortisol from this film system was found to follow first-order dependence on drug concentration. The drug was found to be completely insoluble in lanolin alcohol, and slightly soluble in povidone. Povidone was found to enhance the solubility of Cortisol in water.

Orientador: Luiz Francisco Malmonge / Resumo: Os fertilizantes de liberação modificada têm conquistado âmbitos cada vez maiores nas pesquisas e em utilizações agrícolas devido a suas principais características de menores perdas de nutrientes e por seu menor custo, que envolve menos aplicações no campo e menores quantidades de fertilizantes utilizados, comparado aos fertilizantes convencionais. Este trabalho teve como objetivo elaborar fertilizantes com possível comportamento de liberação modificada, através da incorporação do fosfato de potássio monobásico (KH2PO4) no polímero quitosana, contribuindo, dessa forma, com as três fontes de nutrientes primários essenciais requeridos pelas plantas: nitrogênio, fósforo e potássio, por apenas dois recursos. Foram elaboradas duas amostras diferentes para posterior comparação, análise e aplicação. Os métodos utilizados no preparo das amostras foram: gotejamento em solução básica coagulante e casting. Foram feitas soluções de 8% de quitosana (m/v) dissolvidas em soluções de 5% de ácido acético, e subsequentemente foi adicionado o KH2PO4 (em diferentes concentrações para análise e para aplicação agrícola, foi usada a concentração de 60% (m/m) em relação à massa de quitosana). Foram feitas Microscopia eletrônica de varredura (MEV) para análise morfológica das amostras, Energia dispersiva de raios-X (EDX) para constatação dos elementos contidos nas amostras, o estudo da liberação dos nutrientes em solução aquosa (em pHs 5,4 e 6,7) e por fim, as amostras foram aplicadas em mudas de alf... (Resumo completo, clicar acesso eletrônico abaixo) / Abstract: Modified-release fertilizers have been increasingly used in research and in agricultural uses due to their main characteristics of lower nutrient losses and their lower cost, which involves fewer applications in the field and less quantities of utilized fertilizers, compared to the conventional ones. This work aimed to elaborate fertilizers with possible modified release behavior, through the incorporation of monobasic potassium phosphate (KH2PO4) in the chitosan polymer, thus contributing with the three sources of essential primary nutrients required by plants: nitrogen, phosphorus and potassium, from only two resources. Two different samples were prepared for later comparison, analysis and application. The methods used in preparing the samples were: dripping in a basic coagulant solution and casting. Solutions of 8% chitosan (w/v) were prepared dissolved in solutions of 5% acetic acid, and subsequently KH2PO4 was added (in different concentrations for analysis and for agricultural application, the concentration of 60% (w/w) in relation to the chitosan mass). Scanning electron microscopy (SEM) was performed for the morphological analysis of the samples, energy dispersive X ray (EDX) to verify the elements contained in the samples, the study of the release of nutrients in aqueous solution (at pH 5.4 and 6, 7) and finally, the samples were applied to lettuce seedlings for comparative effect and material efficiency. The results of the EDX spectra showed that in the samples made... (Complete abstract click electronic access below) / Mestre

The development of pyrethroid resistance in mosquitoes threatens the goal of malaria elimination in Africa. Alternative insecticides, e.g. organophosphates, can be considered to control pyrethroid resistant mosquitoes. The problem associated with the deployment of organophosphate-based insecticides is their high volatility. Conventional application forms have a fairly short residual efficacy. This study aimed at extending the residual efficacy of an organophosphate insecticide by using a polymer matrix as a slow release device. A multilayer film blower was used to produce a trilayer film. The middle layer comprised poly(ethylene-co-vinyl acetate), i.e. EVA polymer, impregnated with malathion. This was sandwiched by two low density polyethylene (LDPE) outer layers. These acted as semi-permeable membrane-like barriers that slowed down the release of the contact insecticide to the surfaces of the film. In theory, such a film could be deployed as a long-lasting insecticide-treated wall lining in pyrethroid resistant settings. Scanning electron microscopy (SEM) confirmed the trilayer film structure of the blown film. The malathion release from the film was tracked with Fourier transform infrared spectroscopy (FTIR). The malathion absorption band in the FTIR spectra disappeared gradually over time. Confocal Raman analysis showed a malathion concentration gradient across the thickness of the polyethylene layers. These results suggested diffusion-controlled transport through the LDPE membranes. Bioassays indicated that the residual efficacy of the malathion, against mosquitoes, was increased to about six months. This means that trilayer films, impregnated with an organophosphate, may have potential as alternative mosquito control interventions in pyrethroid resistant settings. / Dissertation (MEng)--University of Pretoria, 2017. / Chemical Engineering / MEng / Unrestricted

The controlled release of therapeutics has been one of the major challenges for scientists and engineers during the past three decades. To address this outstanding problem, the design and fabrication of stimuli-responsive materials are pursued to guarantee the controlled release of cargo at a specific time and with an accurate amount. Upon applying different stimuli such as light, magnetic field, heat, pH change, enzymes or redox, functional materials change their physicochemical properties through physical transformation or chemical reactions, allowing the release of payload agents on demand. This dissertation studied three stimuli-responsive membrane systems for controlled release from films of macro sizes to microcapsules of nano sizes. The first membrane system is a polymeric composite film which can decrease and sustain diffusion upon light irradiation. The photo-response of membranes is based on the photoreaction of cinnamic derivatives. The second one is composite membrane which can improve diffusion upon heating. The thermo-response of membranes comes from the volume phase transition ability of hydrogels. The third one is microcapsule which can release encapsulated agents upon light irradiation. The photo-response of capsules results from the photoreaction of nitrobenzyl derivatives. The study on these membrane systems reveals that stimuli-responsive release can be achieved by utilizing different functional materials on either macro or micro level. Based on the abundant family of smart materials, designing and fabricating stimuli-responsive systems shall lead to various advanced release processes on demand for biomedical applications.

Climent Terol, E. (2012). Design of new hybrid materials: Study of its application in new detection formats and in controlled release applications [Tesis doctoral]. Editorial Universitat Politècnica de València. https://doi.org/10.4995/Thesis/10251/17939 / Palancia