Optimizing Crosslinking Density and Electrical Conductivity for the Potential Application of Multifunctional Electrically Conductive Nerve Guidance Conduits with Immune Compatibility and Nerve Regeneration Capabilities

Abstract

Peripheral nerve injury (PNI) remains a significant clinical challenge due to its complex repair mechanisms and limited regenerative capacity. To address this issue, nerve guidance conduits (NGCs) have been developed as a promising strategy for structural and functional nerve regeneration. In this study, I prepared various conductive hydrogels using gelatin methacryloyl (GelMA) and reduced graphene oxide (rGO) for potential NGC applications with high nerve regeneration efficacy. Specifically, by varying the reduction time of rGO and gelation time of the GelMA hydrogel, I synthesized four types of hydrogels with different conductivity and crosslinking density: 1) low crosslinking density and low conductivity, 2) low crosslinking density and high conductivity, 3) high crosslinking density and low conductivity, and 4) high crosslinking density and high conductivity. These hydrogels were characterized for their physicochemical, mechanical, and electrical properties to evaluate their potential as artificial NGCs. In vitro studies revealed that hydrogels with high crosslinking density and high conductivity showed superior performance for nerve regeneration, as evidenced by significantly enhanced neural outgrowth in dorsal root ganglion (DRG) neurons and anti-inflammatory character by inducing M2 phenotype in bone marrow- derived macrophages (BMDMs). Moreover, the application of electrical stimulation (ES) further augmented these effects. The findings highlight the critical roles of electrical conductivity and crosslinking density in designing effective NGCs and offer new insights into optimizing NGC properties for peripheral nerve repair.