Preparation and properties of thermoreversible hydrogels based on methoxy poly(ethylene glycol)-grafted chitosan nanoparticles for drug delivery systems

A thermoreversible nanoparticle hydrogels based on carboxylated methoxy poly(ethylene glycol)-grafted chitosan (N-CS-g-mPEG) were investigated in this paper. The aqueous dispersion of N-CS-g-mPEG nanoparticle freeze-dried powder (NP-FDP) can undergo reversible gel–sol transition as the temperature changes. The structures of N-CS-g-mPEG NPs and hydrogels were characterized by TEM, DLS and ESEM. Using 5-Fluorouracil (5-FU), bovine serum albumin (BSA) and dexamethasone (DXM) as model drugs, in vitro release behaviors of drug-loaded hydrogels were also investigated. The release results show that there is a sustained release of BSA and DXM from the drug-loaded hydrogel. In vitro cytotoxicity tests investigated by MTT assay indicate that N-CS-g-mPEG is non-toxic to normal mouse embryonic fibroblast cells (3T3). Therefore, the thermoreversible N-CS-g-mPEG NP hydrogels could be potentially applied in a local minimally invasive drug delivery system.