Novel dual-responsive semi-interpenetrating polymer network hydrogels for controlled release of anticancer drugs

Novel dual-responsive hydrogels of semi-interpenetrating polymer networks (semi-IPNs) based on temperature-sensitive N-isopropylacrylamide (NIPAA) and pH-sensitive N-ethylmaleamic acid (NEMA) monomers and sodium alginate polymer were synthesized using free-radical polymerization in the presence of N,N '-methylenebisacrylamide as a crosslinker. Stimuli-responsive properties of the semi-IPN hydrogels showed remarkable sensitivity to both temperature and pH without limitation in NEMA content. Doxorubicin hydrochloride (DOX) as a model drug was efficiently loaded into the hydrogels and the release profiles of drug from them were investigated. The results of in vitro studies showed a quick DOX release in the conditions simulating tumor environment (phosphate-buffered saline [PBS], pH 6.5, 37 degrees C) or endosomes/lysosomes (PBS, pH 5.5, 37 degrees C) compared to simulated human physiological conditions (PBS, pH 7.4, 37 degrees C). In conclusion, the novel poly(NIPAA-co-NEMA) semi-IPN hydrogels could be a promising candidate for targeted and controlled release of anticancer drugs in drug delivery system.