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Updated: Aug 19, 2026
LED-Based In Vitro Screening for Assessing Photoactivable Molecules in Bacterial Photodynamic Inactivation
Published on: January 24, 2025
A study on the bacterial photo-toxicity of phenothiazinium based photosensitisers
Zia Sayed1, Frederick Harris, David A Phoenix
1Department of Forensic and Investigative Science, University of Central Lancashire, Preston, PR1 2HE, England, UK.
Abstract:
"Comet assay" showed light activated (3.15 Jcm-2 over 30 min) phenothiazinium based photosensitisers (PhBPs) to induce photo-damage of Staphylococcus aureus DNA, as indicated by DNA "tails" between 80 and 120 microm. In general, PhBPs exhibited significant singlet oxygen yields (Phi(DeltaPhBP)>0.7), suggesting the use of type II mechanisms of photo-oxidation. However, the photodynamic action of PhBPs on DNA showed generally insignificant production of 7,8-dihydro-8-oxo-2'-deoxyguanosine, normally a major product of type II DNA photo-oxidation. These combined results show DNA to be a major site of action of PhBPs and suggest that this action may involve type II attack on a nucleoside(s) other than guanosine.
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