pH-sensitive polyelectrolyte complex micelles assembled from CS-g-PNIPAM and ALG-g-P(NIPAM-co-NVP) for drug delivery.

In this paper, pH-sensitive polyelectrolyte complex micelles assembled from two oppositely charged graft copolymers chitosan-g-poly(N-isopropylacrylamide) (CS-g-PNIPAM) and sodium alginate-g-poly(N-isopropylacrylamide-co-N-vinyl-pyrrolidone) [ALG-g-P(NIPAM-co-NVP)] were prepared for controlled release of 5-fluorouracil (5-FU). The polyelectrolyte complex micelles showed a narrow size distribution with core-shell structure, where the core formed from positively charged CS and negatively charged ALG by electrostatic interactions. The hydrogen bonding interactions between micelles and 5-FU improved the drug loading. Changing temperature or pH, a controlled drug release was observed. Glutaraldehyde, as a chemical cross-linking agent, was used to improve the micelles stability and decrease the initial burst release. Cytotoxicity assays showed that drug-loaded micelles retained high cell inhibition efficiency in Hela cells. These novel complex micelles with environmentally sensitive properties are expected to be useful in the field of intelligent drug delivery system.