3D Printing rGO/PCL/Mel Bionic Conduit for Peripheral Nerve Regeneration

Abstract The inevitable secondary victimization of patients during the grafting of autogenous nerve necessitates the urgent development of bioactive conduits for the precise repair of peripheral nerve (PN) defects. However, the limited selection of appropriate components and inferior structural designs of many porous scaffolds have hindered satisfactory PN regeneration. In this study, we created a 3D hollow conduit of reduced graphene oxide (rGO) with a hierarchically ordered microstructure through a coaxial printing methodology that enabled a physicochemically cooperative construction process at multiscale. We deposited a mixture of polycaprolactone (PCL) and melatonin (Mel) as the biologically enhancing constitution conformably over the 3D rGO templated conduit. Attributing to its elaborately designed hierarchical structure and arched alignment of 2D micro sheets, the 3D rGO/PCL/Mel hybrid bio-conduit has demonstrated remarkable structural robustness in maintaining ordered pathways and high porosity (98.5 ± 0.24%), which facilitated nerve growth in a complex survival environment in vivo. Furthermore, the excellent combination of properties such as electrical conductivity, biocompatibility, and mechanical properties (with an elastic modulus ranging from 7.06 ± 0.81 MPa to 26.58 ± 4.99 MPa), has led to highly efficient regeneration of well-ordered PN tissue. Systematic evaluations of nerve regeneration and muscle function recovery in an SD rat model with a long nerve defect (> 15 mm) have validated the virtually identical performance of the 3D rGO/PCL/Mel conduit compared to the autogenous nerve graft group. This study confirms a promising approach to clinical PN repair of long defects through the combined regulation of rational structure design on multiscale and indispensable chemical modification of rGO-based functional nerve regeneration conduits.