Preparation and characterization of nanosized silver phosphate loaded hydroxyapatite by single step co-conversion process

The preparation and characterization of silver phosphate nanoparticles loaded hydroxyapatite aiming to enhance the bactericidal performance by a single step co-conversion technique using low temperature phosphorization in the presence of various silver nitrate concentration (AgNO₃, ranging 0.001–0.1 M) was performed. Characterization by using X-ray diffraction, infrared spectroscopy and transmission electron microscopy showed that hydroxyapatite and silver phosphate were the main phases in all converted samples and the microstructure comprised the distribution of spherical-shaped silver phosphate nanoparticles within the cluster of hydroxyapatite nanocrystals. Total silver content (ranging 0.09–5.6%) in the converted samples was found to increase with increasing silver nitrate content. Flexural modulus and strength of converted samples remained unchanged for samples using silver nitrate between 0.001 and 0.01 M, but decreased at greater silver nitrate concentration. Antibacterial activity of two selected samples (0.001 and 0.005 M AgNO₃) against two bacterial strains (Pseudomonas aeruginosa and Staphylococcus aureus) was observed since 100% reduction of viable cells after 24 h contact was detected. Cytotoxic potential by MTT assay of sample using 0.001 M AgNO₃ was only observed at 24 h extraction, but was seen at all extraction periods (24–72 h) for sample using 0.005 M AgNO₃.     

Single step preparation of nanosilver loaded calcium phosphate by low temperature co-conversion process

The preparation and characterization of nanosilver loaded calcium phosphate aiming to enhance the bactericidal performance by a single step co-conversion technique using low temperature ion exchange phosphorization in combination with Tollen's reaction were performed. Silver nitrate was used as a silver ion supply source (0.001-0.1?M) and glucose was employed as a reducing agent. After conversion, surface and shell zones of all samples comprised hydroxyapatite and metallic silver as the main phases regardless of silver nitrate concentration. However, hydroxyapatite, residual calcium sulfate and monetite were found in the core zone when using silver nitrate concentration lower than 0.1?M. The microstructure of all samples comprised the distribution of spherical-shaped silver nanoparticles within the cluster of calcium phosphate nanocrystals. Total silver content (range, 0.09-6.5?%) in the converted samples was found to linearly increase with increasing silver nitrate content. Flexural modulus and strength of converted samples generally decreased with increasing silver content. Effective antibacterial activity of two selected samples (0.001 and 0.005?M AgNO(3)) against two bacterial strains (Pseudomonas aeruginosa and Staphylococcus aureus) was observed. Cytotoxic potentials by MTT assay of both samples were observed at 24 and 48?h extraction respectively.