Synthesis of silver nanoparticle-decorated hydroxyapatite (HA@Ag) poriferous nanocomposites and the study of their antibacterial activities

Herein, we demonstrate a facile and green rapid approach for the synthesis of uniform poriferous hydroxylapatite [Ca-10(PO4)(6)(OH)(2), HA] and poriferous silver nanoparticle (Ag NPs)-decorated hydroxylapatite (HA@Ag) nanocomposites with excellent antibacterial properties. All the nanocomposites were fully characterized in the solid state via various techniques such as X-ray powder diffraction (XRD), transmission electron microscopy (TEM), Fourier transform infrared spectroscopy (FTIR), automatic specific surface area and porosity analysis (BET) and field emission scanning electron microscopy (FESEM). The results show that HA has a porous rod-like structure, which the HA@Ag nanocomposites retained, and the surface of HA was loaded with globular-like Ag NPs with an average diameter of about 5.8 nm, which exhibit a well-crystalline state. The experimental parameters such as pH, the molar ratio of HA and Tollens' reagent, and reductant have a significant effect on the size and distribution of the Ag NPs. Moreover, the antimicrobial activities of HA and HA@Ag against Escherichia coli (E. coli), Pseudomonas aeruginosa (P. aeruginosa) and Staphylococcus aureus (S. aureus) were evaluated via broth dilution, filter paper diffusion, optical density (OD600) and electron microscopy observation. The as-prepared HA@Ag nanocomposites exhibit excellent antibacterial activities, especially for S. aureus. The minimum inhibition concentration (MIC) of HA@Ag is only 3.9 g mL(-1).