Osteomodulatory potential of green-synthesized SA-ZnO/PVA coatings on Ti-6Al-4V alloy

Bone fractures and skeletal injuries resulting from trauma, accidents, or diseases remain a major global health concern, often requiring surgical intervention with orthopedic implants. Titanium-alloys, are commonly employed due to superior structural properties and excellent corrosion resistance. However, these implants lack antibacterial activity and may release toxic ions, increasing the risk of infection, inflammation, and impaired bone healing. Surface modification using bioactive coatings is a promising strategy to overcome these limitations. In this study, a green-synthesized Saraca asoca mediated zinc oxide and polyvinyl alcohol (SA-ZnO/PVA) nanocomposite coating was applied to Ti-6Al-4V substrates, followed by characterization and evaluation of their biological performance. The coated and uncoated substrates were evaluated for mechanical strength, surface topography, and in vitro biological performance using MC3T3-E1 osteoblast cells, including cell viability, migration, reactive oxygen species (ROS) production, and osteogenic differentiation. In vivo studies in a rat femur defect model assessed the potential of coating for bone regeneration, osseointegration, systemic inflammatory response, and visceral organ toxicity. The SA-ZnO/PVA coated substrates maintained mechanical integrity, supported higher osteoblast viability with lower ROS levels compared to uncoated titanium. Coated substrates also promoted faster cell migration, enhanced early osteogenic differentiation, and improved bone formation. These findings suggest that SA-ZnO/PVA coating enhances the antibacterial, cytocompatibility, and hemocompatible properties of Ti-6Al-4V alloy, promoting faster and safer bone healing. The study demonstrates that green synthesized zinc oxide nanoparticles blended PVA coatings effectively enhances the surface properties of Ti-6Al-4V, making it a suitable for orthopedic implant applications.