Characterization of emulsified chitosan - PLGA matrices formed using controlled-rate freezing and lyophilization technique

Abstract

This study evaluated the formation of chitosan-50:50 poly-lactic-co- glycolic acid (PLGA) blend matrices using controlled-rate freezing and lyophilization technique (CRFLT). An emulsion system was used in the presence of 1,2-dimyristoyl-sn-glycero-3-phosphocholine (DMPC), a cellular component, as a stabilizer. Blended scaffolds showed an open pore morphology and homogenous interdispersion of PLGA and chitosan. Forming emulsions after dissolving PLGA in chloroform, benzene, or methylene chloride indicated better emulsion stability with benzene and chloroform. Scaffolds formed by freezing at -20, -78, and -196°C from these emulsions showed significant influence of the solvent and freezing temperature on the microarchitecture of the scaffold. By controlling the concentration of chitosan, scaffolds with greater than 90% porosity were attained. Since the two polymers degrade by different mechanisms, formed scaffolds were analyzed for degradation characteristics for 4 weeks in presence of 10 mg/L lysozyme. These results showed no significant difference in the weight loss and dimension changes, as all scaffolds showed significant (a) weight loss and (b) nearly 60% reduction in volume. Further, pH of the incubation media decreased in all the samples. When cellular activity of green fluorescence protein-transfected smooth muscle cells was analyzed, no apparent cytotoxicity was observed. However, the cell spreading area decreased. In summary, these results show promising potential in tissue engineering and drug delivery applications. © 2006 Wiley Periodicals, Inc.