Antimicrobial activity of nanoparticulate metal oxides against peri-implantitis pathogens.

Dental plaque accumulation may result in peri-implantitis, an inflammatory process causing loss of supporting bone that may lead to dental implant failure. The antimicrobial activities of six metal and metal oxide nanoparticles and two of their composites against bacterial pathogens associated with peri-implantitis were examined under anaerobic conditions. The activities of nanoparticles of silver (Ag), cuprous oxide (Cu(2)O), cupric oxide (CuO), zinc oxide (ZnO), titanium dioxide (TiO(2)), tungsten oxide (WO(3)), Ag+CuO composite and Ag+ZnO composite were assessed by minimum inhibitory (bacteriostatic) concentration (MIC) and minimum bactericidal concentration (MBC) determination against Prevotella intermedia, Porphyromonas gingivalis, Fusobacterium nucleatum and Aggregatibacter actinomycetemcomitans. Time-kill assays were carried out to examine the dynamics of the antimicrobial activity with ZnO nanoparticles. MIC and MBC values were in the range of <100 µg/mL to 2500 µg/mL and <100 µg/mL to >2500 µg/mL, respectively. The activity of the nanoparticles tested in descending order was Ag>Ag+CuO>Cu(2)O>CuO>Ag+ZnO>ZnO>TiO(2)>WO(3). Time-kill assays with ZnO demonstrated a significant decrease in growth of all species tested within 4h, reaching 100% within 2h for P. gingivalis and within 3h for F. nucleatum and P. intermedia. Coating titanium surfaces of dental and orthopaedic implants with antimicrobial nanoparticles should lead to an increased rate of implant success.

Characterisation of copper oxide nanoparticles for antimicrobial applications.

Copper oxide (CuO) nanoparticles were characterised and investigated with respect to potential antimicrobial applications. It was found that nanoscaled CuO, generated by thermal plasma technology, contains traces of pure Cu and Cu2O nanoparticles. Transmission electron microscopy (TEM) demonstrated particle sizes in the range 20-95 nm. TEM energy dispersive spectroscopy gave the ratio of copper to oxygen elements as 54.18% to 45.26%. The mean surface area was determined as 15.69 m(2)/g by Brunau-Emmet-Teller (BET) analysis. CuO nanoparticles in suspension showed activity against a range of bacterial pathogens, including meticillin-resistant Staphylococcus aureus (MRSA) and Escherichia coli, with minimum bactericidal concentrations (MBCs) ranging from 100 microg/mL to 5000 microg/mL. The ability of CuO nanoparticles to reduce bacterial populations to zero was enhanced in the presence of sub-MBC concentrations of silver nanoparticles. Studies of CuO nanoparticles incorporated into polymers suggest release of ions may be required for optimum killing.