Synergistic Photodynamic Antimicrobial Therapy Using 405 nm Laser Diode and Moringa Oleifera-Derived Silver Nanoparticles against Pathogenic Bacteria

Introduction: This study examines the antibacterial capabilities of Moringa oleifera green-synthesized silver nanoparticles (AgNPs-MO), in combination with UV light and a blue laser set at 405 nm, against Staphylococcus aureus and Escherichia coli. Higher concentrations of AgNPs-MO enhanced the antimicrobial activity when exposed to both light treatments. The findings suggest that Moringa oleifera-derived photosensitizers improve the efficacy of photodynamic antimicrobial therapy, offering an eco-friendly approach for enhanced infection control.
Methods: The experimental design comprised four groups: three bacterial groups (A1/A2 and A3/A4) exposed to laser irradiation at varying concentrations and durations of silver nanoparticles, and a control group (T0) that was not exposed to laser irradiation. A photosensitizer produced from Moringa oleifera was also administered to bacteria in groups A2 and A4, and different laser exposure durations were then applied. After incubation, bacterial colonies were measured with a Quebec colony counter.
Results: Statistical analysis using a two-way ANOVA factorial test and post-hoc Tukey test revealed significant reductions in bacterial viability. E. coli exhibited viability reductions of 70.90%, 76.44%, and 79.87% with mmol L-1, mmol L-1.5, and mmol L-2 AgNPs-MO after 180 seconds of laser exposure, respectively. Similarly, S. aureus showed viability reductions of 97.48%, 95.94%, and 94.72% under the same conditions.
Conclusion: At an energy density of 3.44 J/cm2, our approach demonstrated notable efficacy, achieving a 79.87% ± 1.92% inactivation of E. coli and a 97.48% ± 0.78% inactivation of S. aureus. This study suggests promising applications for the combined use of a blue laser, UV radiation, silver nanoparticles, and Moringa oleifera extract in combating infectious bacteria.