Design of Multi-responsive and Actuating Microgel toward On-demand Drug Release

Abstract

Multifunctional colloidal microgels that exhibit stimuli-responsive behavior and excellent biocompatibility have attracted particular attention for developing functional compartmentalized networks. Herein, a series of stimuli-responsive microgels (M0, M1 and M2) were designed by copolymerization of di(ethylene glycol) methyl ether methacrylate (DEGMA) and methacrylic acid (MAA) monomers using hydroxy ethyl methacrylate-coupled azobenzene (HEMA-Az) and ethylene glycol dimetharylate (EGDMA) as crosslinkers. The behaviour of the microgels in response to temperature-, pH- and light was thoroughly investigated by using spectroscopic, microscopic and light scattering techniques. Interestingly, the microgels deswelled with increase in temperature, decrease in pH and with the irradiation of UV light. Such a reversible swelling/deswelling behaviour was exploited for mircogel M2 showing better photoactuation at pH 5 with higher fluid pumping velocity. The actuating microgel M2 was optimized for the loading of ciprofloxacin (Cf) drug to study the release at different temperature, pH and light conditions. Finally, microgel M2 exhibited photoresponsive Cf release in pH 5 and 37 oC toward application in on-demand drug release.