Blue light-emitting diode as the promising photodynamic method for the inactivation of Staphylococcus aureus

Abstract

Staphylococcus aureus is one of the most common bacteria in the human skin and causes various severe infections. Methicillin-resistant Staphylococcus aureus (MRSA) has raised significant concerns and challenges because they are difficult to kill due to their ability to resist many antibiotics. In the present study, a blue light-emitting diode with a wavelength of 405 nm was designed and applied for inactivating S. aureus. We investigated the dependence of the S. aureus inactivation rate on the irradiation factors, including time, distance, and energy dose. The results indicated that irradiation time and distance were observed to significantly affect the growth of S. aureus. In particular, the energy dose of 322.2 J/cm² at a distance of 5 cm for 35 min was recommended to inactivate S. aureus growth completely. The study also proposes the DNA self-repair mechanism causing the delaying time during inactivating S. aureus. Therefore, energy dose is a reliable parameter for designing a single-factor experiment to optimize the irradiation time and distance to obtain a suitable range of values. The comparison between red and blue LED also confirmed the ability of the blue LED to inhibit bacterial growth, while red LED enhances the growth of bacteria. Briefly, our research suggested that blue LED at the wavelength of 405 nm has the potential to be applied in clinical hygiene and food processing as an antimicrobial technique to prevent the development of antibiotic resistance.