Abstract

Objective: This study evaluates the antibacterial activity against mono and multispecies bacterial models and the cytotoxic effects of zinc oxide and copper nanoparticles(ZnO-NPs/Cu-NPs) in cell cultures of human gingival fibroblasts(HGFs). Design: The antibacterial activities of ZnO-NPs and Cu-NPs against 4 bacteria species were tested according to their minimum inhibitory concentrations(MICs) and against mature multispecies anaerobic model by spectral confocal laser scanning microscopy. The viabilities and cytotoxic effects of ZnO-NPs and Cu-NPs to HGFs cell cultures were tested by MTT, LDH assays, production of ROS, and the activation of caspase-3. The results were analyzed using one-way ANOVA followed by Tukey tests, considering p 0.05 as statistically significant. Results: For all strains, MICs of ZnO-NPs and Cu-NPs were in the range of 78.3 mu g/mL-3906 mu g/mL and 125 mu g/mL-625 mu g/mL, respectively. In a multispecies model, a significant decrease in the total biomass volume(mu 3) was observed in response to exposure to 125 mu g/mL of each NPs for which there was bactericidal activity. Significant differences were found between the volumes of viable and nonviable biomass exposed to nanostructures with Cu-NPs compared to ZnO-NPs. Both NPs induced mitochondrial dose-dependent cytotoxicity, ZnO-NPs increases LDH release and intracellular ROS generation. Cu-NPs at a concentration of 50 mu g/mL induced production of cleaved caspase-3, activating the apoptotic pathway early and at low doses. Conclusions: After 24 h, ZnO-NPs are biocompatible between 78-100 mu g/mL and Cu-NPs below 50 mu g/mL. Antibacterial activity in a monospecies model is strain dependent, and in a multispecies model was a lower doses after 10 min of exposure.