Regulation of gene expression using small interfering RNA (siRNA) is a promising strategy for research and treatment of numerous diseases. However, siRNA cannot easily cross the cell membrane due to its inherent instability, large molecular weight and anionic nature. For this reason, a carrier that protects, delivers and unloads siRNA is required for successful gene silencing. The goal of this research was to develop a potential siRNA delivery system for in vitro and in vivo applications using cationic polymers, chitosan and polyethylenimine (PEI), poly(ethylene glycol) (PEG), mannose, and poly(D,L-lactic-co-glycolic acid) (PLGA). Furthermore, the delivery system was constructed in two different ways to explore the effect of mannose location in the structure. In the first approach, mannose and PEG were directly conjugated to the chitosan/PEI backbone, while mannose was connected to the chitosan/PEI backbone through PEG spacer in the second approach. First, the ability of modified chitosan polymers to complex and deliver siRNA for gene silencing was investigated. Despite the modified chitosan polymers successfully formed nanoplexes with siRNA, entered target cells and reduced cytotoxicity of unmodified chitosan, they showed limited gene silencing efficiency. For this reason, modified PEIs were examined to improve in vitro gene knockdown. The modified PEI polymers also complexed with siRNA and facilitated endocytosis of the nanoplexes. In addition, the modifications reduced inherent cytotoxicity of unmodified PEI without compromising the gene silencing efficiency on both mRNA and protein levels. Interestingly, we found that complexation of siRNA with PEI-PEG-mannose resulted in higher cell uptake and gene silencing than complexes made with mannose-PEI-PEG. Finally, the effect of sustained release of the mannosylated pegylated PEI/siRNA nanoplexes on gene silencing was tested by encapsulating the nanoplexes within PLGA microparticles. The modified PEIs enhanced the entrapment efficiency of siRNA into the particles and resulted in reduced initial burst followed by sustained release. Incorporating the modified PEIs increased cellular uptake of siRNA, whereas it did not enhance in vitro gene knockdown efficiency due to the sustained release properties. The modified PEIs reduced the in vitro cytotoxicity and in vivo hepatotoxicity of the PLGA microparticles. In addition, encapsulating the nanoplexes into PLGA microparticles further reduced the cytotoxicity of PEI. Throughout the study, the second structure was proven more efficacious than the first structure in cellular uptake, gene silencing, siRNA encapsulation, and sustained release. We have developed novel polymeric siRNA delivery systems that enhance delivery efficiency and cellular uptake of siRNA. They have great potential for utility as a long-acting siRNA delivery system in biomedical research.

This research centers on the fabrication, characterization, and engineering of inverse opal scaffolds, a novel class of three-dimensional (3D) porous scaffolds made of biocompatible and biodegradable polymers, for applications in tissue engineering and regenerative medicine. The unique features of an inverse opal scaffold include a highly ordered array of pores, uniform and finely tunable pore sizes, high interconnectivity, and great reproducibility. The first part of this work focuses on the fabrication and functionalization of inverse opal scaffolds based on poly(D,L-lactic-co-glycolic acid) (PLGA), a biodegradable material approved by the U.S. Food and Drug Administration (FDA). The advantages of the PLGA inverse opal scaffolds are also demonstrated by comparing with their counterparts with spherical but non-uniform pores and poor interconnectivity. The second part of this work shows two examples where the PLGA inverse opal scaffolds were successfully used as a well-defined system to investigate the effect of pore size of a 3D porous scaffold on the behavior of cell and tissue growth. Specifically, I have demonstrated that i) the differentiation of progenitor cells in vitro was dependent on the pore size of PLGA-based scaffolds and the behavior of the cells was determined by the size of individual pores where the cells resided in, and ii) the neovascularization process in vivo could be directly manipulated by controlling a combination of pore and window sizes when they were applied to a mouse model. The last part of this work deals with the novel application of photoacoustic microscopy (PAM), a volumetric imaging modality recently developed, to tissue engineering and regenerative medicine, in the context of non-invasive imaging and quantification of cells and tissues grown in PLGA inverse opal scaffolds, both in vitro and in vivo. Furthermore, the capability of PAM to monitor and quantitatively analyze the degradation of the scaffolds themselves was also demonstrated.

Apesar de ser uma das doenças infecciosas mais antigas e bem conhecidas, a tuberculose (TB) permanece como a segunda maior causa de morte após a síndrome da imunodeficiência adquirida. A TB é uma doença infecciosa e transmissível, causada pela bactéria Mycobacterium tuberculosis (Mtb), que afeta prioritariamente os pulmões, embora possa acometer outros órgãos e sistemas. O presente trabalho teve como objetivo desenvolver nanofibras e nanoesferas de poli (D,L-láctico co-glicólico) (PLGA) contendo os Insumos Farmacêuticos Ativos (IFAs), rifampicina e isoniazida; caracterizá-las físico quimicamente e determinar a eficiência de encapsulação destes IFAs pelos métodos de eletroforese capilar (CE) e cromatografia líquida de alta eficiência (HPLC). O método de CE para a determinação simultânea dos IFAs antituberculose (isoniazida, rifampicina, pirazinamida e etambutol) foi otimizado por meio de um delineamento de experimentos de mistura com uma abordagem de vértices extremos usando o Software estatístico Minitab 17. Para o desenvolvimento das nanofibras se utilizou a técnica de electrospinning e para as nanoesferas se utilizou a técnica de emulsão/evaporação de solvente. As nanofibras foram caraterizadas por microscopia eletrônica de varredura (SEM), microscopia eletrônica de transmissão (TEM), espectrofotometria de absorção na região do infravermelho (FTIR), calorimetria exploratória diferencial (DSC) e termogravimetria/termogravimetria derivada (TGA) e as nanoesferas foram caracterizadas pelas técnicas de espalhamento dinâmico de luz (DLS), potencial zeta, índice de polidispersão, pH, SEM, TEM, FTIR e DSC. A eficiência de encapsulação dos IFAs nas nanofibras e nas nanoesferas foram realizadas através de duas técnicas analíticas, HPLC e CE, previamente validadas. A eficiência de encapsulação de isoniazida e rifampicina nas nanofibras foi 12,16 % e 5,90 %, respectivamente usando a técnica de HPLC e através da técnica de CE a eficiência de encapsulação foi de 12,30 % e 6,36 %, para isoniazida e rifampicina, respectivamente. A eficiência de encapsulação para a melhor formulação das nanoesferas foi de 2,33 % e 14,75 % para a isoniazida e rifampicina, respectivamente através da técnica de HPLC e uma eficiência de encapsulação de 2,26 % para a isoniazida e 14,22 % para a rifampicina através da técnica de CE. O método por CE teve a vantagem de apresentar um menor tempo de analise, menos de 6 min, com uma adequada resolução entre os picos dos IFAs. O tempo de analise por HPLC foi de 10 min. O método de CE foi menos lesivo ao meio ambiente, devido à pouca quantidade de solventes orgânicos, tornando assim a CE em um método alternativo à HPLC. / Despite being one of the oldest and most well-known infectious diseases, tuberculosis (TB) remains the second leading cause of death after acquired immunodeficiency syndrome. TB is an infectious and transmissible disease caused by Mycobacterium tuberculosis (Mtb) bacteria, which primarily affects the lungs, although it can affect other organs and systems. The present work aimed to develop nanofibers and nanospheres of poly (D, L-lactic co-glycolic) (PLGA) containing Active Pharmaceutical Ingredients (IPAs), rifampicin and isoniazid; characterize them physical-chemically and determine the encapsulation efficiency of these drugs by capillary electrophoresis (CE) and high-performance liquid chromatography (HPLC) methods. A CE method for determination of IPAs (isoniazid, rifampicin, pyrazinamide and ethambutol) was optimized through a design of mixing experiments with an extreme vertex approach using the Minitab 17 statistical Software. For the development of nanofibers and nanospheres the electrospinning and the emulsion/solvent evaporation techniques, respectively were used. Nanofibers were characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM), fourier-transform infrared spectroscopy (FTIR), differential scanning calorimetry (DSC) and thermogravimetry (TGA). Nanospheres were characterized by dynamic light scattering (DLS), zeta potential, polydispersity index, pH, SEM, TEM, FTIR and DSC. The encapsulation efficiency of the IPAs in nanofibres and nanospheres was performed using two analytical techniques, HPLC and EC, previously validated. For nanofibers, the encapsulation efficiency were 12.16 % and 5.90 % for isoniazid and rifampicin, respectivey by using HPLC method and 12,30 % for isoniazid and 6,36 % for rifampicin by CE method. The encapsulation efficiency for the best formulation of nanospheres was 2,33 % and 14,75 % for rifampicin and isoniazid, respectively by using HPLC method and 2,26 % for isoniazid and 14,22 % for rifampicin by EC method. It was shown that CE method presented a shorter analysis time (< 6min) and also and adequate resolution between the IPAs peaks. The time of analysis for the HPLC method was 10 min.CE method was less aggressive to the environment because it uses smaller amount of organic solvents. Therefore the CE is an alternative method to HPLC.

Apesar de ser uma das doenças infecciosas mais antigas e bem conhecidas, a tuberculose (TB) permanece como a segunda maior causa de morte após a síndrome da imunodeficiência adquirida. A TB é uma doença infecciosa e transmissível, causada pela bactéria Mycobacterium tuberculosis (Mtb), que afeta prioritariamente os pulmões, embora possa acometer outros órgãos e sistemas. O presente trabalho teve como objetivo desenvolver nanofibras e nanoesferas de poli (D,L-láctico co-glicólico) (PLGA) contendo os Insumos Farmacêuticos Ativos (IFAs), rifampicina e isoniazida; caracterizá-las físico quimicamente e determinar a eficiência de encapsulação destes IFAs pelos métodos de eletroforese capilar (CE) e cromatografia líquida de alta eficiência (HPLC). O método de CE para a determinação simultânea dos IFAs antituberculose (isoniazida, rifampicina, pirazinamida e etambutol) foi otimizado por meio de um delineamento de experimentos de mistura com uma abordagem de vértices extremos usando o Software estatístico Minitab 17. Para o desenvolvimento das nanofibras se utilizou a técnica de electrospinning e para as nanoesferas se utilizou a técnica de emulsão/evaporação de solvente. As nanofibras foram caraterizadas por microscopia eletrônica de varredura (SEM), microscopia eletrônica de transmissão (TEM), espectrofotometria de absorção na região do infravermelho (FTIR), calorimetria exploratória diferencial (DSC) e termogravimetria/termogravimetria derivada (TGA) e as nanoesferas foram caracterizadas pelas técnicas de espalhamento dinâmico de luz (DLS), potencial zeta, índice de polidispersão, pH, SEM, TEM, FTIR e DSC. A eficiência de encapsulação dos IFAs nas nanofibras e nas nanoesferas foram realizadas através de duas técnicas analíticas, HPLC e CE, previamente validadas. A eficiência de encapsulação de isoniazida e rifampicina nas nanofibras foi 12,16 % e 5,90 %, respectivamente usando a técnica de HPLC e através da técnica de CE a eficiência de encapsulação foi de 12,30 % e 6,36 %, para isoniazida e rifampicina, respectivamente. A eficiência de encapsulação para a melhor formulação das nanoesferas foi de 2,33 % e 14,75 % para a isoniazida e rifampicina, respectivamente através da técnica de HPLC e uma eficiência de encapsulação de 2,26 % para a isoniazida e 14,22 % para a rifampicina através da técnica de CE. O método por CE teve a vantagem de apresentar um menor tempo de analise, menos de 6 min, com uma adequada resolução entre os picos dos IFAs. O tempo de analise por HPLC foi de 10 min. O método de CE foi menos lesivo ao meio ambiente, devido à pouca quantidade de solventes orgânicos, tornando assim a CE em um método alternativo à HPLC. / Despite being one of the oldest and most well-known infectious diseases, tuberculosis (TB) remains the second leading cause of death after acquired immunodeficiency syndrome. TB is an infectious and transmissible disease caused by Mycobacterium tuberculosis (Mtb) bacteria, which primarily affects the lungs, although it can affect other organs and systems. The present work aimed to develop nanofibers and nanospheres of poly (D, L-lactic co-glycolic) (PLGA) containing Active Pharmaceutical Ingredients (IPAs), rifampicin and isoniazid; characterize them physical-chemically and determine the encapsulation efficiency of these drugs by capillary electrophoresis (CE) and high-performance liquid chromatography (HPLC) methods. A CE method for determination of IPAs (isoniazid, rifampicin, pyrazinamide and ethambutol) was optimized through a design of mixing experiments with an extreme vertex approach using the Minitab 17 statistical Software. For the development of nanofibers and nanospheres the electrospinning and the emulsion/solvent evaporation techniques, respectively were used. Nanofibers were characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM), fourier-transform infrared spectroscopy (FTIR), differential scanning calorimetry (DSC) and thermogravimetry (TGA). Nanospheres were characterized by dynamic light scattering (DLS), zeta potential, polydispersity index, pH, SEM, TEM, FTIR and DSC. The encapsulation efficiency of the IPAs in nanofibres and nanospheres was performed using two analytical techniques, HPLC and EC, previously validated. For nanofibers, the encapsulation efficiency were 12.16 % and 5.90 % for isoniazid and rifampicin, respectivey by using HPLC method and 12,30 % for isoniazid and 6,36 % for rifampicin by CE method. The encapsulation efficiency for the best formulation of nanospheres was 2,33 % and 14,75 % for rifampicin and isoniazid, respectively by using HPLC method and 2,26 % for isoniazid and 14,22 % for rifampicin by EC method. It was shown that CE method presented a shorter analysis time (< 6min) and also and adequate resolution between the IPAs peaks. The time of analysis for the HPLC method was 10 min.CE method was less aggressive to the environment because it uses smaller amount of organic solvents. Therefore the CE is an alternative method to HPLC.