Nanogel fabricated from oxidized sodium alginate and hydrophilic-modified chitosan exhibits great potential as pH-responsive drug delivery system.

This study designed a pH-sensitive nanogel based on sodium alginate and chitosan. In order to improve the solubility of chitosan and reduce the toxicity caused by crosslinking agent, a specific synthetic pathway was designed. Structural modification of chitosan with various hydroxypropyl and carboxyl groups afforded a chitosan derivative (CHPCS), which was mixed with the oxidized sodium alginate (AO) to provide the desired sodium alginate-chitosan nanogel (AO/CHPCS-NG). Morphology study indicated that the nanogel had spherical shape with average diameter of 40–50 nm. Berberine (BBR) was used as the model drug for drug loading study, which produced BBR-loaded nanogel (AO/CHPCS-NG-BBR) with pH-sensitive release ability in vitro. Cytotoxicity investigation showed that AO/CHPCS-NG-BBR had no obvious effect on proliferation of human umbilical vein endothelial cells (HUVECs), which proved its low toxicity on normal human cells. In contrast, AO/CHPCS-NG-BBR exhibited high toxicity against human hepatoma cells (HepG2), thus confirming that the synthesized nanogel should be a potential drug carrier and had widespread applications. [ABSTRACT FROM AUTHOR]