Systematic investigation and controlled synthesis of Ag/Ti co-doped hydroxyapatite for bone tissue engineering

Abstract

Hydroxyapatite (HA) is a cornerstone bio ceramic in bone tissue engineering applications, prized for its inherent biocompatibility and structural resemblance to natural bone tissue. However, both porous and dense, conventional HA formulations face notable stability and mechanical robustness constraints, impeding their broader utility. We introduce an innovative biomaterial synthesized via a straightforward and efficient sol-gel method to surmount these challenges and imbue novel scaffolds with multifunctional capabilities. Leveraging a double doping strategy, our approach seeks to enhance mechanical performance and incorporate antibacterial features, maintaining the biocompatibility of HA-based scaffolds for advanced tissue engineering applications. In pursuit of this objective, we synthesized Ag-doped, Ag, Ti-doped, and Ti-doped HA samples to explore the impact of varying dopant types and concentrations on various structural, thermal, crystallographic, chemical, morphological, mechanical, and biocompatibility characteristics. X-ray Diffraction (XRD) analysis confirmed the presence of apatitic phase compositions across all samples, while Fourier-transform Infrared Spectroscopy (FTIR) data corroborated phosphate formation and functional group identification. Scanning Electron Microscopy (SEM) studies revealed a correlation between particle size and dopant concentration, consistent with XRD findings. Nanoindentation results indicated optimal mechanical performance was achieved with balanced incorporation of Ag and Ti ions despite increased Vickers microhardness with higher Ti concentrations. All doped samples exhibited effective antibacterial activity against Escherichia coli (E. coli) and Staphylococcus aureus (S. aureus), except for the Ti-doped HA sample. Moreover, the HA sample co-doped with equal amounts of Ag and Ti demonstrated noncytotoxicity for human lung cancer (A549) cells. In contrast, all doped samples exhibited cytotoxicity towards human prostate cancer cell (PC3) cells. Statistical analysis confirmed a synergistic enhancement of biocompatibility and mechanical performance in HA samples doped with Ag and Ti ions in equal proportions. In conclusion, our study presents a simple and effective approach for enhancing HA's mechanical and antibacterial properties through co-doping with Ag and Ti. This innovative biomaterial holds significant promise for advancing bone tissue engineering applications.