Production of polyhydroxyalkanoate nanoparticles using a green solvent

Abstract

AbstractBiopolymer nanoparticles (NPs) produced from poly(3‐hydroxybutyrate‐co‐3‐hydroxyvalerate) (PHBV) are typically formed by first dissolving the polymer in organic solvents. In order to eliminate the use of toxic solvents, an alternative “green” solvent system using glacial acetic acid was used in this study for the preparation of NPs via nanoprecipitation. The influence of various factors on the resulting particle size was investigated including the use of an emulsifying agent, temperatures of stock and receiving solutions, and concentration of stock solution. The addition of emulsifier significantly reduced the NP size, whereas temperature had minimal influence on the particle size over the tested range. By varying the concentration of the stock solution, the size of the NPs can be adequately controlled. The minimum size of NPs prepared using a stock solution of 0.5 ml at 80°C into a 100 ml receiving solution was 70 nm with a narrow size distribution. Imaging by scanning electron microscopy revealed smooth spherical NPs and thermal and structural analysis showed only minor changes in properties in comparison with the source PHBV powder. Overall, the results show that glacial acetic acid is an appropriate alternative solvent for the dissolution of PHBV and the subsequent formation of biopolymer NPs.