Tailoring the interfaces of titanium with strontium and zinc: a surface functionalization approach with in vitro and in vivo evaluation for bone implants

Abstract

Recently, surface modification of titanium with bioactive elements has emerged as a promising approach to enhance the biological performance of medical implants. In this study, a multifunctionalized nanonetwork surface, mimicking the extracellular matrix, was generated by employing the alkali-mediated surface modification approach. Subsequently, strontium (Sr) and zinc (Zn) ions were incorporated into this nanonetwork, and the results were evidenced by EDX, XPS, and HR-TEM analyses. The surface morphology demonstrated an improvement in surface characteristics and properties, such as roughness, wettability, and phase formation, as evidenced by AFM, water contact angle measurement, and Raman spectroscopy. Resistance to the microbes Staphylococcus aureus (Gram positive) and Escherichia coli (Gram negative) indicates the antibacterial activity of Zn/ZnO in accordance with the direct contact method and live–dead assay results. While cell material interaction studies with MG-63 cells suggest enhanced cell proliferation rates with respect to cytoskeleton evaluation, mitochondrial potential, live–dead assay, and extracellular mineralisation, with strong support for the cytocompatibility of the material. In vivo studies of 3D-printed surface functionalised Ti implants in a rat model, along with the osteogenic gene expression profile, further reveal the enhanced osseointegration capacity of our multifunctionalized surface. Thus, this Sr and Zn multi-element incorporated nanotitania layer over the Ti metal is expected to be a good candidate for next-generation implant development.