Rapid electric field-driven biomimetic multi-gradient conductive hydrogels for regulating neural cell behavior

Peripheral nerve injury remains a major clinical challenge due to the limited availability of autologous nerve grafts and the risk of donor-site morbidity. Neural tissue engineering demands biomimetic scaffolds that can replicate the native extracellular matrix (ECM) and provide combined physicochemical gradients to guide neural cell behavior. However, integrating multiple functional gradients into a single scaffold has proven difficult. Here, we present an electric field-driven approach to rapidly fabricate a biomimetic conductive hydrogel featuring simultaneous gradients in stiffness, conductivity, and morphology. This is achieved by incorporating β-sheet-rich silk nanofibrils (BSNF)-stabilized reduced graphene oxide (rGO) into a polyisocyanopeptide (PIC) matrix. BSNF effectively improves rGO dispersion and reinforces mechanical strength, while rGO imparts favorable conductivity to the hydrogel. Upon application of a direct current electric field, the negatively charged BSNF/rGO complexes migrate directionally toward the anode, enabling controllable and rapid formation of the desired gradients. Under electrical stimulation, the multi-gradient hydrogel markedly regulates the behavior of SH-SY5Y cells: axon length is increased up to ∼1.7-fold, and neurite number is significantly enhanced, while neurite branching shows no significant alteration. Notably, neurites preferentially extend toward stiffer and more conductive regions, demonstrating clear combined guidance. This rapid and electric-driven multi-gradient strategy holds strong promise for neural tissue engineering and peripheral nerve repair.