Skin optical properties from 200 to 300 nm support far UV-C skin-safety in vivo

• Published in: Journal of photochemistry and photobiology. B, Biology Vol. 247; p. 112784
• Main Authors: Zamudio Díaz, Daniela F., Klein, Anna Lena, Guttmann, Martin, Zwicker, Paula, Busch, Loris, Kröger, Marius, Klose, Holger, Rohn, Sascha, Schleusener, Johannes, Meinke, Martina C.
• Format: Journal Article
• Language: English
• Published: Elsevier B.V 01-10-2023
• Subjects: 233 nm LED; Absorption coefficient; DNA damage; Effective scattering coefficient; Inflammatory reactions; MC simulations; np; Inflammatory reactions; D; iMCS; Effective scattering coefficient; DNA damage; LR; Tc; SC; Td; Rd; CFU; MC simulations; CLSM; ED; Tt; TEWL; μa; 233 nm LED; g; Absorption coefficient; LED; MED; n; UV-C; nc; CPD; μs; ITA; 6–4PP; MCRT
• ISSN: 1011-1344; 1873-2682
• DOI: 10.1016/j.jphotobiol.2023.112784

The growing threat of multi-drug resistant pathogens and airborne microbial diseases has highlighted the need to improve or develop novel disinfection methods for clinical environments. Conventional ultraviolet C (UV-C) lamps effectively inactivate microorganisms but are harmful to human skin and eyes upon exposure. The use of new 233 nm far UV-C LEDs as an antiseptic can overcome those limitations. In this research, the light penetration into the skin was elucidated for the UV-C region (<300 nm) by measuring the scattering and absorption of skin layers and inverse Monte Carlo simulation, and further confirmed by the first clinical pilot trial in which healthy volunteers were irradiated with a dose of 60 mJ/cm2 at 233 nm. The radiation is strongly absorbed in the stratum corneum, resulting in minimal skin damage without inducing inflammatory responses. The results suggest that 233 nm far UV-C light emitting diodes (LEDs) could effectively inactivate microorganisms, while being safe and soft for the skin.
•Optical Properties of human skin (Stratum Corneum, Epidermis, Dermis) from 200 to 300 nm•Simulation of penetration depth and light distribution for 200 nm – 300 nm•Skin safety of 233 nm far-UVC LEDs irradiation in healthy humans in vivo•Minimal and superficial skin damage without induction of inflammatory responses