title: Aspects of the in vitro bioactivity and antimicrobial properties of Ag(+)- and Zn (2+)-exchanged 11 A tobermorites.
abstract: 11 A tobermorite, Ca(5)Si(6)O(16)(OH)(2) . 4H(2)O, is a layer lattice ion exchange mineral whose potential as a carrier for Ag(+) and Zn(2+) ions in antimicrobial, bioactive formulations has not yet been explored. In view of this, the in vitro bioactivity of Ag(+)- and Zn(2+)-exchanged 11 A tobermorites and their bactericidal action against S. aureus and P. aeruginosa are reported. The in vitro bioactivity of the synthetic unsubstituted tobermorite phase was confirmed by the formation of bone-like hydroxycarbonate apatite (HCA) on its surface within 48 h of contact with simulated body fluid. The substitution of labile Ag(+) ions into the tobermorite lattice delayed the onset of HCA-formation to 72 h; whereas, the Zn(2+)-substituted phase failed to elicit an HCA-layer within 14 days. Both Ag(+)- and Zn(2+)-exchanged tobermorite phases were found to exhibit marked antimicrobial action against S. aureus and P. aeruginosa, two common pathogens in biomaterial-centred infections.
authors.affiliation: University of Greenwich, Chatham Maritime, Kent, UK. nj_coleman@yahoo.co.uk
authors.forename: Nichola J
authors.initials: NJ
authors.lastname: Coleman
mesh_terms: D000900:Anti-Bacterial Agents / Q000737:chemistry*; D001031:Apatites / Q000378:metabolism; D001672:Biocompatible Materials / Q000737:chemistry*; D001826:Body Fluids; D017610:Calcium Compounds / Q000737:chemistry*; D002254:Carbonates / Q000378:metabolism; D015169:Colony Count, Microbial / Q000379:methods; D008956:Models, Chemical; D011550:Pseudomonas aeruginosa / Q000187:drug effects; D017640:Silicates / Q000737:chemistry*; D012834:Silver / Q000737:chemistry*; D017550:Spectroscopy, Fourier Transform Infrared; D013211:Staphylococcus aureus / Q000187:drug effects; D013329:Structure-Activity Relationship; D014961:X-Ray Diffraction; D015032:Zinc / Q000737:chemistry*
chemical_list: D000900:Anti-Bacterial Agents; D001031:Apatites; D001672:Biocompatible Materials; D017610:Calcium Compounds; D002254:Carbonates; D017640:Silicates; C413465:hydroxycarbonate apatite; C512534:tobermorite; D012834:Silver; D015032:Zinc