Microporous PDMAEMA-based stimuli-responsive hydrogel and its application in drug release

The microporous hydrogels (Pn-Cm gels) composed of poly(dimethylaminoethyl methacrylate) and carboxymethylchitosan were synthesized in situ radical polymerization by using nano g-Fe2O3 particles as pore-agent. The microporous structure formed through eliminating the Fe2O3 particles was designed to achieve a faster response rate and better drug loading effect. Comparing to the neat gels, Pn-Cm gels exhibit deteriorative mechanical properties with the increased pores, while the gels still keep the elastic network structure which could bear some degree of tensile and compression deformation. Meantime, Pn-Cm gels show similar temperature and pH double responsiveness with same isoelectric point shrink as that of neat gels, the swelling ability decreases slightly, and the deswelling rate increases with the increase of pores. Moreover, the 5-fluorouracil was used as a target drug to explore the potential of this gel applied as drug-release system. For Pn-Cm gels, the more pores and carboxymethyl chitosan inside the gels are beneficial to the drug loading, all gels show a burst release of drug, being followed by a slow and sustained release with different rate. Comprehensively, the Pn-Cm gels exhibit a better sustained release effect in the simulated stomach condition (pH=2.1), the related release mechanism could be interpreted by the superposition of Fickian diffusion. (C) 2017 Wiley Periodicals, Inc.