Aspects of the in vitro bioaetivity and antimicrobial properties of Ag~+- and Zn~(2+)-exchanged 11 A tobermorites

摘要

11 A tobermorite, Ca_5Si_6O_(16)(OH)_2; 4H_2O, 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-for-mation 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.