Silver nanoparticles deposited on calcium hydrogenphosphate – silver phosphate matrix; biological activity of the composite

The composite containing nanosilver uniformly deposited on matrix composed of CaHPO₄  x 2H₂ O (brushite, ca 89 mass %), CaHPO₄  (monteonite, ca 9.5 mass%), and Ag₃ PO₄  (0.5 mas%) was obtained by addition of calcium nitrate and silver nitrate aqueous solution at 30:1 Ca:Ag molar ratio into excess of (NH₄ )₂ PO₄  solution at pH 5.0 – 5.5. The isolated solid was characterized by STEM, XRD, and LDI mass spectrometry. It has been found that nanosilver was uniformly distributed within composite as <10 nm diameter sized nanoparticles. Determination of silver by AAS showed that 60% of silver is present as Ag(0) nanoparticles, the present as matrix Ag₃ PO₄  as identified by XRD method. The composite showed strong growth inhibition in E. coli and P. aeruginosa strains, and moderate towards S. aureus. The C. albicans cells were the most resistant to the tested material, although still composite was moderately cytostatic for the yeast.