Fabrication of tannic acid/poly(N-vinylpyrrolidone) layer-by-layer coating on Mg-based metallic glass for nerve tissue regeneration application

For improving recovery rates and functional outcomes in large nerve defects, a nerve guide conduit, in addition to topographic, physical and chemical cues should provide contact guidance and adequate mechanical support for cell migration and axon outgrowth. Among biomaterials, magnesium (Mg) metal has potential to support nerve regeneration owing to its electrical conductivity, biodegradation and ability to be formed into wires, filaments and ribbons. However, rapid degradation of magnesium can pose a challenge. Mg-based metallic glasses with desirable features including favorable biocompatibility, proper biodegradation and good mechanical properties are a good alternative to crystalline Mg alloys. This study investigates the biocorrosion and biocompatibility of Mg-Zn-Ca metallic glass ribbon with Mg70Zn26Ca4 composition. For controlling biocorrosion, layer-by-layer coating of tannic acid/ poly(N-vinylpyrrolidone) was applied on Mg70Zn26Ca4 ribbon and characterized by SEM and FTIR. Immersion and potentiodynamic polarization test results indicated that coating significantly improved the corrosion resistance of Mg70Zn26Ca4. Schwann cells were selected for the cytocompatibility evaluation of samples due to their key role in peripheral nerve regeneration and ability to repair spinal cord injuries. The MTT assay and cell morphology results showed good biocompatibility for Mg70Zn26Ca4 metallic glass as a promising candidate for nerve regeneration and implantable nervous prosthetic devices.