Synthesis of copper-silver doped hydroxyapatite via ultrasonic coupled sol-gel techniques: structural and antibacterial studies

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Fabrication of hydroxyapatite (HA) via doping with metal ions to enhance its antibacterial properties has attracted much interest. The present study aims to synthesize copper-silver doped hydroxyapatite particles (Cu-Ag doped HA) with an improved antibacterial activity through a sol-gel technique coupled with ultrasonic irradiation. The doping materials consist of Cu2+ and Ag+ ions with precursor molar ratios of 0.0, 0.25, 0.50, 0.75 and 1.0. The physicochemical properties of Ca9.0Cu1.0-xAgx(PO4)6(OH)2 samples were investigated using X-ray diffraction, Fourier-transform infrared spectroscopy (FT-IR), and transmission electron microscopy coupled with energy dispersive X-ray analysis (TEM-EDS). Characterization studies revealed that Cu2+ and Ag+ ions were incorporated into a hexagonal framework of HA. The main functional groups were identified as hydroxyl (OH−) and phosphate (PO43−) moieties. Their morphologies were rod-shaped with various diameters and particle size distributions, depending on the molar ratio of Cu2+ to Ag+. Antibacterial activity was evaluated using an agar well diffusion method against Staphylococcus epidermis, S. aureus, Bacillus subtilis, B. cereus, and Pseudomonas aeruginosa. It was found that Cu-Ag doped HA is an effective antibacterial agent. Ca9.0Cu0.5Ag0.5(PO4)6(OH)2 showed the best antibacterial performance against all bacterial strains with inhibition zones ranging from 13 to 17 mm, indicating its suitability as an antibacterial material in biomedical applications.