Initial immune response to a FRET-based MMP sensor-immobilized silk fibroin hydrogel in vivo.

Abstract To investigate the initial immune response to biodegradable silk fibroin (SF) hydrogels in vivo, a Forster/fluorescence resonance energy transfer (FRET)-based sensor was developed to detect matrix metalloproteinase (MMP) activity (FRET-MMPS) and immobilized to SF hydrogel. FRET-MMPS immobilized to SF hydrogel in vitro displayed intra-molecular FRET more than inter-molecular FRET, and MMP activity was detected through a decrease in FRET signal intensity. Then, the SF hydrogel modified with FRET-MMPS was implanted into mice subcutaneously, and it was observed that the FRET signal intensity decreased significantly soon ( Statement of significance Silk fibroin (SF) materials are degraded gradually by the immune response. Immune cells, such as macrophages, break down implanted SF materials on a timescale of weeks or months, but the initial (