Chitosan-g-PEG nanoparticles ionically crosslinked with poly(glutamic acid) and tripolyphosphate as protein delivery systems.

In the present study chitosan grafted copolymers with poly(ethylene glycol) (CS-g-PEG) were prepared and studied using PEG with molecular weights 2000 and 5000g/mol. The materials were characterized using (1)H NMR, FTIR and WAXD techniques. These polyelectrolytes were ionically crosslinked with tripolyphosphate (TPP) and poly(glutamic acid) (PGA) at different polymer/crosslinking agent ratios (1:1, 2:1, 3:1 and 4:1, w/w) for the nanoencapsulation of bovine serum albumin (BSA). Prepared nanoparticles are spherical in shape with a mean diameter ranging from 150 to 600 nm. The size depends mainly to the molecular weight of the PEG and the crosslinking agent used. The PEG molecular weight also seems to affect the release rate of BSA especially the first burst effect which appears to be high in copolymers containing PEG5000, compared with copolymer prepared with PEG2000, and it is also higher when PGA was used as crosslinking agent, instead of TPP.