Disinfection with 405nm Visible Light

Disinfection with 405nm Visible Light


LEDs in the 405 nm range provide continuous and safe microbial inactivation for occupied spaces, aiding in reduction of HAIs. 

While UVC is a proven germicidal technology for terminal cleaning, the use of visible light in the 405-470 nm wavelength range for microbial inactivation has gained ground as it is considered safe for human exposure. Photodynamic inactivation of microbes using this visible light is triggered due to the excitation of intracellular light receptors such as porphyrins, present in bacterial cell walls [2]. These endogenous porphyrins exhibit high light sensitivity at 405 nm wavelength (absorption peak of the Soret band of porphyrins) and the interaction of 405 nm light with these molecules, in the presence of oxygen, leads to the creation of reactive oxygen species. This causes damage to intracellular components, resulting in cell death by oxidative stress [3]. While in comparison with UVC, the 405 nm light requires higher dosages to achieve similar microbial reductions, the higher efficiency of 405 nm LEDs and the potential to be used continuously without vacating spaces makes this a favorable technology for use in highly-occupied healthcare settings. High-intensity narrow spectrum lights using 405 nm LEDs have been used in burn-units, intensive care rooms, and operating rooms and have been integrated with general lighting fixtures, without the need for specific operator training. The technology has been proven effective against gram-positive and gram-negative bacteria, fungi, yeasts and spores [4]. However, effectiveness against enveloped viruses such as the SARS-CoV-2, while potentially possible, needs to be proven [1].


[1] Sabino, Caetano P et al., “Light-based technologies for management of COVID-19 pandemic crisis,” Journal of photochemistry and photobiology. Vol. 212, 2020.

[2] Hamblin, M. R., and T. Hasan, “Photodynamic therapy: a new antimicrobial approach to infectious disease? ,” Photochem. Photobiol. Sci., Vol. 3, 2004.

[3] Maclean, M. et al , “405 nm light technology for the inactivation of pathogens and its potential role for environmental disinfection and infection control,” Journal of Hospital Infection, Vol. 88, 2014.

[4] Murdoch L.E et al. “Bactericidal Effects of 405 nm Light Exposure Demonstrated by Inactivation of Escherichia, Salmonella, Shigella, Listeria, and Mycobacterium Species in Liquid Suspensions and on Exposed Surfaces,” Volume 2012, 2012.

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