Evaluation of Antimicrobial and Antibiofilm Activities of Copper Oxide Nanoparticles within Soft Denture Liners against Oral Pathogens

Abstract

Objectives. Soft denture liners provide a favorable environment for adhesion and colonization of microorganisms. This in vitro study aimed to examine the efficacy of different concentrations of copper oxide nanoparticles (CuO NPs) incorporation into soft denture liner on the biofilm formation of the microbial species. Methods. Field Emission Scanning Electron Microscopy (FESEM) images from NPs were recorded. Antifungal susceptibility testing of CuO NPs against five standard strains of Candida albicans (CBS 10261, 1905, 1912, 1949, 2730), Streptococcus mutans (ATCC35668), Streptococcus sobrinus (ATCC27607), and Streptococcus salivarius (ATCC9222) was performed by the broth microdilution method with the Clinical and Laboratory Standards Institute reference method. The biofilm inhibition percentages of CuO NPs on the soft denture liners were determined by XTT assay. Results. The characterization of CuO NPs by scanning electron microscope (SEM) analyses confirmed the synthesis of NPs with appropriate structure and size with a mean diameter of 18.3 ± 9.1 nm. The CuO NPs successfully inhibited the growth of the tested standard strains of C. albicans and Streptococcus spp. at concentrations ranging from 64 to 128 µg mL−1. Indeed, incorporation of CuO NPs at a concentration of 500 µg mL−1 into the soft denture liners exhibited a significant activity (75%) in inhibition of C. albicans. biofilm formation in a dose-dependent manner. The biofilm formation of C. albicans in the presence of CuO NPs was lower than Streptococcus spp. in comparison with the control group ( $p<0.05$ ). Conclusion. Incorporation of CuO NPs significantly decreased the colonization and plaque formation of the oral pathogens, especially C. albicans accumulation. These NPs may be useful as a promising agent for the antimicrobial management of soft denture liner materials.