Cytocompatibility and antibacterial properties of copper-magnesium nanoparticles for potential dental applications

Copper-magnesium nanoparticles (Cu-Mg NPs) have attracted increasing interest in dentistry because of their reported biological and antibacterial properties. This study evaluated the cytocompatibility of hybrid Cu-Mg NPs with oral fibroblasts, osteoblasts, and dental pulp stem cells (DPSCs) and investigated their antibacterial activity against Streptococcus mutans and Enterococcus faecalis, two clinically relevant oral pathogens associated with cariogenic and endodontic infections.

Cytocompatibility was assessed at 24, 48, and 72 h using the MTT assay, live/dead staining, and phase-contrast microscopy after exposing cells to Cu-Mg NP suspensions (0.05-6.4 mg/mL). Antibacterial activity was evaluated using NP suspensions ranging from 0.025 to 12.8 mg/mL to determine the minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC). Bacterial survival was further quantified by colony counting at 0.8 and 1.6 mg/mL.

Cu-Mg NPs maintained cell viability above 70% above at concentrations of 0.05-1.6 mg/mL across all cell types and at concentrations up to 3.2 mg/mL for DPSCs. Higher concentrations (3.2 and 6.4 mg/mL) produced dose-dependent reductions in cell viability, consistent with the live/dead staining results and observed morphological changes. The MIC for both bacterial species and the MBC were 1.6 mg/mL and 12.8 mg/mL, respectively. Colony counting assays confirmed reduced bacterial survival at 0.8 and 1.6 mg/mL.

Cu-Mg NPs exhibited antibacterial activity against S. mutans and E. faecalis while maintaining cytocompatibility at lower concentrations. These findings demonstrate a concentration-dependent response and support further evaluation of Cu-Mg NPs in applications requiring antimicrobial activity and cytocompatibility.