Laser Assisted Selective Texturing and Alloying of Titanium Implant surfaces for Enhanced Bactericidal and Osteointegration Properties

Orthopedic device-related infections (ODRIs) in implants represent a critical and multifaceted healthcare challenge, necessitating a comprehensive understanding of their impact on patient well-being, management, and prevention. While titanium-based (Ti) implants are commonly used due to their favorable corrosion resistance, excellent biocompatibility, and mechanical properties similar to that of bone, the development of bacterial infections owing to ORDI remains a daunting concern. Functionalizing the implant surface with antimicrobial agents, without altering the bulk properties of the Ti alloy, presents an effective approach to improving the efficacy of orthopedic implants and elevating patient outcomes. In this context, we have developed a two-step process involving laser texturing and alloying of silver (Ag) nanocomposites into the widely used titanium alloy (Ti6Al4V) implant surfaces, thereby conferring antibacterial properties. The process involved spray coating silver nanoparticles onto the implant surface, followed by heat sintering and laser-induced alloying of Ag into the Ti alloy. The local heat generated by the laser process enables simultaneous intermetallic alloying and texturing of the implant surface, enhancing its surface roughness without affecting its bulk mechanical properties. A systematic study was conducted by varying the laser beam power to analyze the structural, morphological, and elemental composition of the surface, utilizing X-ray diffraction (XRD), scanning electron microscopy (SEM), and energy-dispersive X-ray spectroscopy (EDX) analysis. The results demonstrated that the developed laser-textured surface exhibited enhanced wettability, increased surface roughness, and effective alloying of silver on the implant surface without compromising bulk mechanical properties. The optimized laser-textured surface was subjected to a seven-day antibacterial test against a model population of gram-positive (<i>Staphylococcus aureus</i>) and gram-negative bacteria (<i>Escherichia coli</i>). Furthermore, the osteointegrative properties of the developed surface were assessed through in-vitro bone mineralization assays using Mesenchymal Stem Cells (MSC), and the calcified extracellular matrix levels were measured. The results indicated a two-fold increase in bone cell mineralization and long term antibacterial properties for the optimized laser-textured surface compared to the control Ti alloy surfaces. By modifying the implant surface, the antibacterial properties can help prevent bacterial colonization, while the enhanced osteointegration properties can promote bone cell adhesion and colonization. Ultimately, this scalable laser-assisted alloying approach holds the potential to enhance the long-term success of orthopedic implants and improve patient outcomes.