title: Antibacterial nanosized silver substituted hydroxyapatite: synthesis and characterization.
abstract: The silver (0.5-3 at %) substituted nanosize hydroxyapatites (AgHAs) were synthesized by microwave processing. The X-ray diffraction (XRD) peaks are very broad, indicating that the AgHAs were of nanosize (30 nm). Transmission electron microscopy analysis shows needle-like morphology of AgHA, having length 60-70 nm and width 15-20 nm. The AgHA phase was stable up to 700 degrees C without any secondary phases. The antibacterial effect of AgHA against Escherichia coli and Staphylococcus aureus was observed by spread plate method, even for low concentration of silver ions (0.5%) with 1 x 10(5) cells/mL of respective bacterial culture, after a 48 h incubation period. However, some colonies of E. coli were seen with a high dose of 1 x 10(8) cells/mL after 24 h. The zone of inhibition by disc diffusion test method was found to vary with the amount of silver in the sintered AgHA pellets, for both the bacteria, after 24 h of inoculation. Osteoblast cell attachment in varying density was noticed on AgHA samples with 0.5, 1.0, and 1.5% silver substitution. However, osteoblast spreading was significantly greater on 0.5% AgHA compared to 1.0 or 1.5% substituted AgHA samples. Thus, the low amount of AgHA has a potential of minimizing the risk of bacterial contamination, without compromising the bioactivity, and is expected to display greater biological efficacy in terms of osseointegration.
authors.affiliation: Department of Metallurgical and Materials Engineering, Indian Institute of Technology Madras, Chennai 600036, India.
authors.forename: N
authors.initials: N
authors.lastname: Rameshbabu
authors.forename: T S
authors.initials: TS
authors.lastname: Sampath Kumar
authors.forename: T G
authors.initials: TG
authors.lastname: Prabhakar
authors.forename: V S
authors.initials: VS
authors.lastname: Sastry
authors.forename: K V G K
authors.initials: KV
authors.lastname: Murty
authors.forename: K
authors.initials: K
authors.lastname: Prasad Rao
mesh_terms: D000900:Anti-Bacterial Agents; D001424:Bacterial Infections / Q000517:prevention & control; D001672:Biocompatible Materials / Q000737:chemistry / Q000494:pharmacology; D002448:Cell Adhesion; D002460:Cell Line; D004926:Escherichia coli / Q000187:drug effects; D006801:Humans; D006882:Hydroxyapatites; D053758:Nanoparticles / Q000737:chemistry; D016348:Osseointegration / Q000187:drug effects*; D010006:Osteoblasts / Q000166:cytology*; D012834:Silver / Q000737:chemistry / Q000494:pharmacology; D013211:Staphylococcus aureus / Q000187:drug effects; D023822:Tissue Engineering / Q000379:methods*
chemical_list: D000900:Anti-Bacterial Agents; D001672:Biocompatible Materials; D006882:Hydroxyapatites; D012834:Silver