Drug controlled releasing system based on polypyrrole modified multi-responsive hydrogel constructed from methacrylic acid and N-isopropylacrylamide

Stimuli-responsive hydrogels could effectively solve the problem that traditional drug carriers were difficult to deliver drug on-demand. However, some shortcomings such as complex preparation, single responsiveness, and narrow application still needed to be urgently overcome. In view of this situation, two kinds of hydrogels were elaborately designed in this work. In the unique ethanol/water mixed solvent, a homogeneous reaction system consisting of methacrylic acid (MAA) and N-isopropylacrylamide (NIPAM) was constructed, and a dual-responsive P(MAA-co-NIPAM) hydrogel was successfully synthesized. A near-infrared (NIR) responsive multi-functional PPy/P(MAA-co-NIPAM) hydrogel was subsequently prepared by the introduction of polypyrrole (PPy) via in-situ polymerization. NIR-responsive swelling, photodeformable, and photothermal ability of the hydrogel under NIR light irradiation were explored. It was found that rapid shape and temperature change could be achieved within 60 s for PPy/P(MAA-co-NIPAM) hydrogel. With doxorubicin as a model drug, the drug loading and in vitro controlled releasing behaviors under different conditions were comprehensively investigated. It was confirmed that the multi-responsive hydrogels had controllable drug releasing ability under different stimulations, which would realize potential targeted drug delivery in physiological environment. This work might provide a new synthetic method of hydrogel for drug releasing, which was expected to expand the potential application domain of hydrogel materials in NIR penetration targeted therapy.