Related Experiment Video
Updated: Nov 26, 2025

Studying Chronic Exposure of Mice to Ultraviolet B Radiation
Published on: August 19, 2025
Ultraviolet A irradiation induces ultraweak photon emission with characteristic spectral patterns from biomolecules
Katsuhiko Tsuchida1, Masaki Kobayashi2
1Shiseido Global Innovation Center, 1-2-11, Takashima, Nishi-Ku, Yokohama, 220-0011, Japan. katsuhiko.tsuchida2@shiseido.com.
Abstract:
Oxidative stress is associated with photoaging of the skin as well as with skin cancer, and is therefore, critical to monitor. Ultraweak photon emission (UPE) is extremely weak light generated during the oxidative process in the living body and has been used as a non-invasive and label-free marker for the evaluation of oxidative stress. However, the mechanism of UPE generation is not clear. Therefore, we aimed to elucidate the molecular mechanism underlying UPE generation by analyzing the spectra of UPE generated from biomolecules in the skin during ultraviolet A (UVA) exposure. The spectra of UVA-induced UPE generated from linoleic acid, linolenic acid, elastin, phospholipids, and 5,6-dihydroxyindole-2-carboxylic acid were measured, and the spectrum of human skin tissue was also obtained. The spectral patterns varied for the different biomolecules and the peaks were distinct from those of the skin tissue. These results suggested that the UPE generated from skin tissue is a collection of light emitted by biomolecules. Moreover, we proposed that UPE is generated through a photosensitization reaction and energy transfer. The identified characteristic spectral patterns of UPE can be useful to elucidate UVA-induced oxidative stress in the skin, with implications for prevention and treatment of photoaging and skin diseases.
Related Concept Videos
Mutations
Chromosomal Alterations Are Large-Scale Mutations
While point mutations are changes in a single nucleotide in...
Ultraviolet and Visible (UV–Vis) Spectroscopy: Overview
UV–Vis Spectrometers
UV–Vis Spectroscopy: Molecular Electronic Transitions
Pigmentation
Melanin occurs in two primary forms: eumelanin that provides black and brown pigment and pheomelanin that provides red color. Dark-skinned individuals produce more melanin than those with pale...
UV–Vis Spectrum
The UV–Vis spectrum of a molecule is the plot of its absorbance versus wavelength. The plot is drawn by taking molar...

