A novel exposure mode based on UVA-LEDs for bacterial inactivation

Area of Science:

• Microbiology
• Photochemistry
• Biophysics

Background:

• Ultraviolet light-emitting diodes (UV-LEDs) are emerging as efficient disinfection sources.
• UVA-LEDs offer advantages over UVC-LEDs, including higher power, lower cost, and deeper penetration.
• Optimizing UV disinfection protocols is crucial for effective microbial control.

Purpose of the Study:

• To propose and validate a novel fractionated exposure mode using UVA-LEDs for enhanced bacterial disinfection.
• To investigate the impact of fractionated exposure parameters on bacterial inactivation.
• To elucidate the underlying mechanisms of enhanced inactivation.

Main Methods:

• Experiments were conducted using Staphylococcus aureus (S. aureus) as a model organism.
• Fractionated UVA exposure was compared with single-dose exposure.
• Inactivation kinetics, photoreactivation, dark repair, and reactive oxygen species generation were analyzed.

Main Results:

• Fractionated UVA exposure with a 15-minute interval significantly increased S. aureus inactivation compared to single exposure.
• Fractionated exposure altered inactivation rate constants and eliminated shoulders in fluence-response curves.
• The enhanced inactivation was attributed to increased •OH radical production and reduced bacterial repair mechanisms.

Conclusions:

• Fractionated UVA-LED exposure is a promising strategy for improving bacterial disinfection efficacy.
• This method demonstrates universality across different bacterial types (Gram-positive and Gram-negative).
• The findings provide novel insights for optimizing UV disinfection technologies.