In vitro studies of biocompatible thermo-responsive hydrogels with controlled-release basic fibroblast growth factor

In this study, poly (γ-glutamic acid) with 72% sulfonated carboxyl groups and poly(N-isopropylacrylamide) (γ-PGA-S72/PNIPAAm) semi-interpenetrating network (semi-IPN) hydrogels were developed and used as a soft-wet platform for cell harvesting and controlled release of basic fibroblast growth factor (bFGF). The physical and chemical properties of the γ-PGA-S72/PNIPAAm semi-IPN hydrogels were systemically investigated. Furthermore, the specific binding and controlled release of growth factor were confirmed by enzyme-linked immunosorbent assay and the released bFGF shown to promote NIH-3T3 cell proliferation in 7 days. Cells could spontaneously detach from γ-PGA-S72/PNIPAAm semi-IPN hydrogels without enzyme treatment. This work demonstrates that the γ-PGA-S72/PNIPAAm semi-IPN08 hydrogel may be an excellent carrier for avoiding the sudden release and low bioactivity of growth factors in culture systems.