Engineering a wirelessly self-powered neural scaffold based on primary battery principle to accelerate nerve cell differentiation

Electrical stimulation displayed tremendous potential in promoting nerve regeneration. However, the current electrical stimulation therapy required complex traversing wires and external power sources, which significantly limited its practical application. Herein, a self-powered nerve scaffold based on primary battery principle was gradient printed by laser additive manufacturing technique. Specifically, poly-L-lactide (PLLA) containing Ag₂O and Zn nanoparticles was prepared as the positive and negative electrode of the scaffold respectively, and PLLA/PPy was prepared as the middle conductive segment. In simulated body fluid, the negative electrode underwent oxidation to lose electrons and become positively charged. The lost electrons were transferred to the positive segment in a directed and orderly manner via the middle conductive segment, causing the positive electrode to be enriched electrons and become negatively charged. Subsequently, two segments can generate a potential difference to form an electric field, further generating current. Not merely, the redox process can release Ag⁺ and Zn²⁺ to endow the scaffold with antibacterial properties. Results showed that the scaffold could generate a current of up to 17.2 μA, which promoted a 14-fold increase in calcium ion influx and increased the mRNA expression of neuronal markers MAP2 by 24-fold. Moreover, the antibacterial rates of the scaffold against E. coli and S. aureus could reach 92.6 % and 91.9 %, respectively.