Chemical stability, mass loss and hydrolysis mechanism of sterile and non- sterile lipid-core nanocapsules: The influence of the molar mass of the polymer wall

摘要

The purpose of this study was to investigate the chemical stability and the mechanism of hydrolysis of the polyester wall of lipid-core nanocapsules (LNC) dispersed in water comparing sterile and non-sterile formulations. Sterile or non-sterile LNC formulations (LNCS and LNC, respectively) were prepared using poly(epsilon-capro-lactone) (PCL) with different molar masses (M-n 10 kg mol(-1), M-n 80 kg mol(-1) and a mixture (1:9, w/w) of both PCL). All formulations presented unimodal size distribution profile without significant changes (p .05) after 60 days. Molar weight changes, fraction of chain scissions and hydrolysis mechanism of LNC under storage (60 days; 5 degrees C) were determined by size exclusion chromatography (SEC). The highest PCL weight loss was observed for the non-sterile formulations (LNC 1-45%; LNC 2-32%; LNC 3-27%). In turn, the sterile formulations showed a lower weight loss, proving that biotic hydrolysis was responsible for accelerating hydrolysis of the LNC even when stored at low temperature (5 degrees C). In conclusion, the predominant hydrolysis mechanism was of the non-catalyzed type.