Synthesis and properties of pH sensitive carboxymethylated hydroxypropyl chitosan nanocarriers for delivery of doxorubicin

A novel amphiphilic polymer, carboxymethylated hydroxypropyl chitosan (HPCMS) was successfully synthesized for delivery of doxorubicin (DOX). The chemical structure and thermal stability were characterized by FTIR, 1H NMR and TGA, respectively. In aqueous medium, HPCMS could self-assembled into micelles with a low critical aggregation concentration of 0.54 mg/mL. The DOX-loaded HPCMS micelles showed a considerable drug-loading capacity of around 13 wt%. The prepared micelles were spherical morphology with average hydrodynamic diameter 300-380 nm and zeta potential of around −13 mv. The HPCMS/DOX micelles showed a sustained and pH-dependent drug release behavior in vitro and good stability. The drug release data could be well fitted with the Higuchi kinetic model, suggesting a diffusion-controlled mechanism. The diffusional exponent values indicated non-Fickian diffusion where the diffusion of drug and polymer relaxation had an important role in the process of drug release.