Study of conductive nerve conduits for anti-inflammatory and antioxidant effects

Replacing autologous nerve grafts with nerve conduits is the prevailing direction for the treatment of peripheral nerves, though the repair of hollow nerve conduits remains unsatisfactory. In this study, cysteinylated zein (l-Zein) was prepared through a disulfide exchange reaction between the disulfide bonds of cysteine (Cys) and those of zein (Zein). Subsequently, electrospinning was utilized to fabricate hollow nerve conduits loaded with berberine (BBR) by means of hydrogen bonding and physical encapsulation. Hydrogels were prepared by ionic cross-linking of Zein with pectin (Pec), and were subsequently loaded with melatonin (MT) and graphene oxide (GO) through physical adsorption and encapsulation. A hydrogel was then injected into a hollow catheter to form a hydrogel composite nerve conduit (l-ZBZPGM). The hydrogels exhibited a continuous porous network structure with pore size distribution between 100 and 200 μm. Most of the hydrogels exhibited porosity exceeding 70% and the compressive modulus was 0.42 ± 0.025 MPa. A hydrogel exhibited a residual mass ratio of 35.15% ± 1.87% at the end of the 30 d degradation period, achieved peak release on day 18 with a release rate of 83.31% ± 3.64%, and had an electrical conductivity of 1.23 ± 0.482 × 10-3 S cm-1, meeting the requirements for nerve repair. The lack of cytotoxicity and the anti-inflammatory and antioxidant properties of l-ZBZPGM were demonstrated using RSC96 cells and Raw264.7 cells. Additionally, through electrical stimulation experiments, it was proven that the addition of GO can promote the proliferation of nerve cells. The biological materials used in this study are of simple composition, and their degradation products may have a minimal impact on the microenvironment. The findings suggested that l-ZBZPGM was more conductive to peripheral nerve regeneration.