Fully biodegradable ion-induced silk fibroin-based triboelectric nanogenerators with enhanced performance prevent muscle atrophy

Applying electrical stimulation (ES) on nerve or muscle denervation can significantly restore the nerve function and prevent muscle atrophy. The triboelectric nanogenerator (TENG) can couple the mechanical energy and electrical energy for ES. However, the triboelectric performance of fully biodegradable TENGs and the effect of ES need to be optimized and verified. Here, the triboelectric performance of silk fibroin (SF) is regulated by ions to fabricate SF-TENGs with full biodegradability, good biocompatibility, and excellent output. This SF-TENG shows a good electrostimulation recovery effect and is used for function restoration of the injured sciatic nerve and innervated muscle. Li+ effectively improves the dielectric constant and increases the positively charged ability of SF. The highest output power density of SF-TENG is 128 mW/m2, which is superior to most reported fully biodegradable TENGs. The morphology, protein expression levels, neural/muscular function are assessed to evaluate the recovery of damaged nerves and innervated muscle. The function restoration of the injured nerve and innervated muscle under ES of SF-TENG is significantly close to the normal nerve and muscle. This TENG has great potential to achieve in vivo energy generation, ES, and biodegradability as an implantable electrical stimulator for the therapy of nerve, muscle, and tissue injury.