Antibacterial effect of red laser-activated silver nanoparticles synthesized with grape seed extract against Staphylococcus aureus and Escherichia coli

Living organisms, particularly humans, frequently encounter microorganisms such as bacteria, fungi, and viruses in their surroundings. Silver nanoparticles are widely used in biomedical devices because of their antibacterial and antiviral properties. The study evaluates the efficacy of red laser and silver nanoparticles from grape seed extract (AgNPs-GSE) in reducing Gram-negative Escherichia coli and Gram-positive Staphylococcus aureus bacteria, which cause infections. The sample comprised three groups: a control group without laser irradiation (T0), Escherichia coli samples (A1 and A2) irradiated with a 405-nm diode laser at different times and concentrations of silver nanoparticles, and Staphylococcus aureus samples (A3 and A4) illuminated with a 405-nm diode laser at different times and concentrations. Bacteria in groups A2 and A4 were treated with a photosensitizer (PS) made from grape seed extracts, incubated for 10 min, and then irradiated for 90, 120, 150, and 180 s. The samples were cultured on TSA media, set at 37 °C, counted using a Quebec colony counter, and analyzed using ANOVA and Tukey tests with a significance level of p < 0.05. The study illustrated that the combination of 10 µl of AgNPs-GSE, exposure to a red laser at 405 nm, and an energy density of 3.44 J/cm² effectively photoinactivated both Escherichia coli and Staphylococcus aureus bacteria. For Escherichia coli bacteria irradiated for 180 s with concentrations of 1 mM, 1.5 mM, and 2 mM AgNPs-GSE, bacterial viability decreased by 64.50%, 70.74%, and 79.53%, respectively. Similarly, Staphylococcus aureus bacteria, subjected to irradiation for 180 s with concentrations of 1 mM, 1.5 mM, and 2 mM AgNPs-GSE, demonstrated reductions in bacterial viability by 70.23%, 73.47%, and 85.04%, respectively. The findings from the present study indicate that at an energy density of 3.44 J/cm², it was possible to inactivate Escherichia coli by 79.53% and Staphylococcus aureus by 85.04%.