Photodynamic antibacterial activity of green-synthesized gold nanoparticles from mangosteen peel extract using blue...

diseases caused by antibiotic-resistant bacteria pose a growing global health challenge. Photodynamic Therapy (PDT), which uses light-activated photosensitizers to kill bacteria, offers a promising alternative. This study evaluates the antibacterial efficacy of gold nanoparticles synthesized from mangosteen peel extract (AuNPs-GML) combined with blue diode laser irradiation against Escherichia coli (E. coli) and Staphylococcus aureus (S. aureus), two common pathogens.

Four treatments were applied: control (no treatment), AuNPs-GML alone, blue laser irradiation alone (405 nm), and a combination of AuNPs-GML with laser irradiation. Samples were incubated at 37 °C for 24 h before bacterial viability was assessed. Statistical analysis was performed using Two-Way ANOVA and Tukey's post hoc test (p < 0.05).

Results showed that combining AuNPs-GML with blue laser irradiation significantly enhanced bacterial inactivation compared to laser or nanoparticles alone. At 180 seconds irradiation and 2 mM AuNPs-GML concentration, bacterial reduction reached 86.25% for E. coli and 72.84% for S. aureus at an energy density of 3.34 J/cm2.

This study demonstrates the potential of AuNPs-GML activated by blue laser PDT as an effective antibacterial treatment against resistant bacteria.