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Updated: May 20, 2026

Inactivation of Pathogens via Visible-Light Photolysis of Riboflavin-5′-Phosphate
Published on: April 6, 2022
Inactivation of bacteria in plasma
Ali Oguz Er1, Jie Chen, Thomas C Cesario
1Department of Chemistry, University of California, Irvine, CA 92697, USA.
Abstract:
The photo-inactivation rate of bacteria by methylene blue, MB, was found to be significantly lower in plasma than in water, saline, and PBS solutions. The spectroscopic data and ultrafast time resolved transient spectra and kinetics presented show that methylene blue photo-bleaches faster and to a larger degree in plasma and the MB excited singlet and triplet state populations in plasma are much lower in plasma than in water and PBS solutions. The optical density, OD, of MB in plasma was found to decrease by ~50% after a minute of illumination with 661 nm light, while under identical conditions the OD in PBS solution decreased by only 1%. Based on these data and the effect of the plasma proteins on MB photochemistry, a mechanism is proposed that accounts for the low inactivation rate of bacteria in plasma.
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