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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. Highlights: Ultrasonic treatment combined with a sol-gel technique synthesized well dispersed, rod-shaped Cu-Ag doped HA. Ca9.0Cu0.5Ag0.5(PO4)6(OH)2 has excellent antibacterial activity against Gram-positive and Gram-negative bacteria. Cu-Ag doped HA nanoparticle is an effective antibacterial material in biomedical applications. [ABSTRACT FROM AUTHOR]

The present work aims to synthesize hydroxyapatite (HAp) via green template addition using glutinous rice (GR) in combination with sol-gel route under various calcination temperatures (500-900 °C). The physicochemical properties of GR-HAp were analyzed using X-ray diffraction, Fourier-transform infrared spectroscopy, scanning electron microscopy, transmission electron microscopy, and energy dispersive X-ray analysis. The utilization of GR as template in HAp synthesis resulted in the formation of GR-HAp particles that are less crystalline. Surface morphology revealed discrete, rod-shaped GR-HAp particles were formed at low calcination temperature (500-600 °C), while larger particles were formed as temperature was increased. Results confirmed that higher calcination temperature led to the transformation of HAp into various phases including β-Ca3(PO4)2, CaO, and β-NaCa(PO4). In addition, the formation of smaller, elongated GR-HAp particles with diameter of 75-180 nm and homogenous particle size distribution was attained at 900 °C. The antibacterial activity was evaluated via disc diffusion method against four Gram-positive bacteria including B. cereus, B. subtilis, S. aureus, and S. epidermidis, and two Gram-negative bacteria including E. coli and P. aeruginosa. The GR-HAp powder calcined at 900 °C showed strong antibacterial performance against all bacterial strains with inhibition zones ranging from 11.66-16.66 mm, which indicates its suitability to be utilized as a material in biomedical applications. Use of GR as template resulted in formation of less crystalline particles with reduced aggregation.Higher calcination temperature led to formation of β-Ca3 (PO4)2 and β-NaCa(PO4) phases.GR-HAp calcined at 900 °C showed strongest antibacterial performance against all bacterial strains. [ABSTRACT FROM AUTHOR]