ABSTRACT
ABSTRACT Enzymatically crossliked gelatin hydrogel was submitted to two different drying methods: air drying and freeze drying. The resulting polymeric tridimensional arrangement (compact or porous, respectively) led to different thermal and swelling properties. Significant differences (p < 0.05) on thermal and mechanical characteristics as well as swelling in non-enzymatic gastric and intestinal simulated fluids (37 ºC) were detected. Water absorption data in such media was modelled according to Higuchi, Korsmeyer-Peppas, and Peppas-Sahlin equations. Freeze dried hydrogel showed Fickian diffusion behavior while air dried hydrogels presented poor adjustment to Higuchi model suggesting the importance of the relaxation mechanism at the beginning of swelling process. It was possible to conclude that the same gelatin hydrogel may be suitable to different applications depending on the drying process used.
Subject(s)
Water , Hydrogels/metabolism , Freeze Drying , Gelatin/metabolism , Time Factors , Calorimetry, Differential Scanning , Microscopy, Electron, Scanning , Hydrogels/chemistry , Mechanical Phenomena , Gelatin/ultrastructure , Gelatin/chemistryABSTRACT
ABSTRACT:The encapsulation of progesterone in poly (hydroxybutirate-co-hydroxyvalerate) (PHBV), poly (ε-caprolactone) (PCL), poly (L-lactic acid) (PLLA) nanoparticles and PHBV/PCL and PHBV/PLLA blend nanoparticles was investigated in this research. Nanoparticles were produced by miniemulsion/solvent evaporation technique with lecithin as surfactant and were characterized regarding to z-average diameter (Dz) and polydispersity (PDI), progesterone recovery yield and encapsulation efficiency. Possible interactions between progesterone and the polymer matrices were investigated by Fourier Transform Infrared Spectroscopy (FTIR). High recoveries (up to 102.43±1.80% for the PHBV/PLLA blend) and encapsulation efficiencies (up to 99.53±0.04% for PCL) were achieved and the nanoparticles presented narrow size distribution (0.12±0.03 for PLLA). PCL nanoparticles (217.5±2.12nm) presented significant difference with the Dz from all the other formulations (P<0.05). The most evident interaction between progesterone and the nanoparticles polymeric matrix was found to PHBV/PCL due to the increase in the intensity of the band located in 1631 cm-1.
RESUMO:A encapsulação de progesterona em nanopartículas de poli(hidroxibutirato-co-hidroxivalerato) (PHBV), poli (ε-caprolactona) (PCL), poli (L-ácido lático) (PLLA) e em nanopartículas blenda de PHBV/PCL e PHBV/PLLA foi investigada neste trabalho. As nanopartículas foram produzidas pela técnica de miniemulsificação/evaporação do solvente com lecitina como surfactante e foram caracterizadas em relação ao diâmetro médio em intensidade (Dz) e o índice de polidispersão (PDI), rendimento de recuperação e eficiência de encapsulação de progesterona. Possíveis interações entre progesterona e as matrizes poliméricas foram investigadas por Espectroscopia de Infravermelho por Transformada de Fourier (FTIR). Valores elevados de rendimento de recuperação (de até 102,43±1,80% para a blenda PHBV/PLLA) e eficiência de encapsulação (de até 99,53±0,04% para PCL) foram obtidos e as nanopartículas apresentaram distribuição de tamanho estreita (0,12±0,03 para PLLA). As nanopartículas de PCL (217,5±2,12nm) apresentaram diferença significativa com todas as outras formulações (P<0,05) quanto ao Dz. A interação mais evidente entre progesterona e a matriz polimérica das nanopartículas foi para a blenda PHBV / PCL, devido ao aumento na intensidade da banda localizada em 1631 cm-1.