Integration of 3% Silver-Doped Hydroxyapatite Coated on Alumina Using Radio Frequency Magnetron Sputtering for Superior Bioactivity, Mechanical and Electrical Properties, and Wear Resistance

The research investigates the integration of 3% silver-doped hydroxyapatite (Ag-HAP) onto a hexagonal alumina substrate with a matching structure to reduce interface strain utilizing radio frequency magnetron sputtering (RFMS). This method aims to improve film adhesion while enhancing the bioactivity, antimicrobial properties, and wear resistance of biomedical implants. Hydroxyapatite (HAP) has excellent biocompatibility and is widely used in bone implants due to its similarity to bone minerals, but it suffers from brittleness and limited mechanical strength. By doping Ag with HAP, mechanical and antimicrobial properties are enhanced, addressing infection and material longevity challenges. Alumina (Al₂O₃) is known for its mechanical strength and wear resistance, making it a suitable substrate for implants; however, its lack of bioactivity requires modification. The RFMS technique ensures a uniform and well-adhered nanocoating of Ag-HAP on alumina, creating a composite material that balances alumina's durability with silver-doped HAP bioactivity and antimicrobial benefits. The study reveals improved mechanical properties, such as increased hardness and wear resistance, along with enhanced antibacterial efficacy, making the composite material promising for orthopedic applications. The characterization of coatings using various analytical techniques such as EDS, FESEM, FTIR, and XRD confirms the formation and stability of Ag-HAP, while electrical properties are described by dielectric measurements. The changes in the lattice parameters, grain size, and pore size led to changes in hardness, coefficient of friction, and ultimately, the material's biocompatibility. Improvement in corrosion resistance after coating can be due to intermetallic compound formation at the interface. Biocompatibility was studied through assays that show favorable results, supporting the potential of Ag-HAP/Al₂O₃ in implantology. The mechanism of improvement in the antibacterial mechanism against <i>E. coli</i> and <i>S. aureus</i> is proposed. This research proposes a novel solution to implant-related challenges by combining silver-doped hydroxyapatite mechanical and biological advantages with alumina, thereby optimizing both biocompatibility and structural integrity for long-term use in biomedical implants.