Degradable nanohydrogel with high doxorubicin loadings exhibiting controlled drug release and decreased toxicity against healthy cells.

A new nanogel/drug carrier of 100-150 nm size, based on poly(N-isopropylacrylamide-co-sodium acrylate) and degradable crosslinker (cystine derivative), was synthesized. Using the electrostatic interactions between the carboxylic groups in the polymer network and the protonated amine groups of doxorubicin it was possible to load the drug into the carrier to a very high level of 28-30% relative to the dry mass of the polymer. The presence of the -S-S- groups made the polymer network susceptible to degradation by glutathione. The size of the nanoparticles was small enough to enable them to easily penetrate the cells. The MTT assay indicated that compared to free doxorubicin the nanogel particles loaded with doxorubicin were more cytotoxic against the MCF-7 and A2780 cancer cells, while they were 150 times less toxic against the MCF-10A healthy cells. The new carrier nanoparticles appeared also to be useful for prolonged drug delivery.