Effects of Polyethylene Glycol on Mechanical and Degradation Properties of Silk Fibroin Coatings for Deep Brain Stimulation Electrodes

In deep brain stimulation (DBS), metal cannulas for flexible electrode implantation risk secondary tissue injury. This study proposes silk fibroin/polyethylene glycol (SF/PEG) composite coating as a biodegradable alternative. Fourier transform infrared spectroscopy (FT-IR) confirmed PEG incorporation in SF matrices (1:1 and 10:1 ratios). Nanoindentation revealed PEG reduced elastic modulus from 9.4 GPa (pure SF) to 3.9 GPa (SF/PEG 1:1) and enhanced ductility. Degradation tests showed SF/PEG 1:1 achieved near-complete weight loss within 72 h in PBS at 37°C, while SF/PEG 10:1 exhibited slower degradation. These results demonstrate SF/PEG composites as tunable, rapidly degradable coatings for DBS electrodes, eliminating cannula removal and improving surgical safety.