Injectable pH-responsive poly (γ-glutamic acid)-silica hybrid hydrogels with high mechanical strength, conductivity and cytocompatibility for biomedical applications

A novel injectable pH-responsive poly (gamma-glutamic acid) (PGA)-silica hybrid hydrogel with controlled structural and physicochemical properties has been developed. Hybrid hydrogels are composited of PGA and 3-glycidoxypropyl trimethoxysilane (GPTMS) with different content of silica which is derived from hydrolyzed tetraethylorthosilicate (TEOS). In this hybrid system, GPTMS is employed as a coupling agent and TEOS is used for adjusting the silica content. Effects of the silica content on the morphology, microstructure, mechanical strength, swelling behavior, drug delivery performance, conductivity and cytocompatibility are investigated. Results reveal that the microporous structure, compressive strength, swelling as well as drug delivery behavior, and in vitro cytocompatibility of hybrid hydrogels are effectively tailored by adjusting the silica content. Besides the pHresponsive swelling and drug release behaviors, the hybrid hydrogel possesses good conductivity as well as high sensitivity to external strain. Therefore, the prepared hybrid hydrogels reveal great application potential as promising injectable biomaterials for biomedical applications.