A Novel Silver-Based Metal-Organic Framework Incorporated into Nanofibrous Chitosan Coatings for Bone Tissue Implants

In this work, new multi-layer nanocomposite coatings comprised of chitosan (CS) nanofibers functionalized using an innovative silver-based metal-organic framework (SOF) were developed. The SOFs were produced via a facile process using green and environmental-friendly materials. The CS-SOF nanocomposites were coated on hierarchical oxide (HO) layers fabricated on titanium substrates by an innovative two-step etching process. X-ray diffraction revealed fruitful production of the SOF NPs and their stable crystalline structure within the nanocomposite coatings. Energy-dispersive x-ray spectroscopy approved uniform SOFs distribution in the CS-SOF nanocomposites. Atomic force microscopy indicated more than 700% increased nanoscale roughness for the treated surfaces compared to the bare sample. In vitro MTT assay revealed proper cell viabilities on the samples, however, high SOFs concentration led to less biocompatibility. All coatings demonstrated positive cell proliferation rates up to 45% after 72 h. Antibacterial studies showed significant inhibition zones against Escherichia coli and Staphylococcus aureus bacteria with 100-200% effective antibacterial activities. Electron microscopy exhibited excellent cell-implant integration for the CS-SOF nanocomposite surfaces due to the attached cells with expanded morphologies and long filopodia. The prepared coatings showed high apatite formation capability and bone bioactivity.