BACKGROUND AND OBJECTIVES: The rise of antibiotic resistance in bacteria poses a significant challenge in hospital settings. In response, researchers are exploring various novel drug candidates to combat bacterial infections. Among these promising candidates are metal nanoparticles. This study investigates the potential of Cu nanoparticle (Cu-NP) synthesized using green method for their antimicrobial and anti-virulence properties. MATERIALS AND METHODS: CU-NPs were synthesized using Ralstonia sp. SM8 culture and the iron sulfate precursor. To characterize the post-synthesis properties of the nanoparticles, various techniques were employed, including UVvisible spectrometry, field emission scanning electron microscopy (FESEM), X-ray energy dispersion spectroscopy (EDX), dynamic light scattering (DLS), zeta potential measurement, and Fourier transform infrared spectroscopy (FTIR). Successful synthesis of Cu-NPs was confirmed by UV-visible spectrometry, revealing a strong absorption peak at 228 nm. After the successful synthesis of the nanoparticles, their antibacterial and anti-virulence properties were measured by standard bacterial methods. RESULTS AND DISCUSSION: The nanoparticles were primarily spherical with an average size of 69 nm. The DLS confirmed an average hydrodynamic diameter of 78.2 nm with a polydispersity index (PDI) of 0.38, indicating moderate size distribution. The zeta potential of -5.1 mV suggests good colloidal stability of the nanoparticles. FTIR analysis suggested that proteins play a role in nanoparticle formation and stabilization. The Cu-NPs exhibited promising antibacterial activity, with MICs ranging from 0.16 to 0.33 µg/mL and MBCs ranging from 0.33 to 0.66 µg/mL. Additionally, Cu-NPs significantly affected most bacterial virulence factors at sub-MIC concentrations. These effects included inhibition of biofilm formation at MIC/2 concentration, inhibition of motility for motile bacteria at MIC/2, synergistic interactions with cefixime and penicillin antibiotics, and inhibition of the S. aureus efflux pump. These findings suggest that the green-synthesized nanoparticles can effectively inhibit the tested bacteria, making them potentially useful antibacterial agents.
