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Proceedings Paper

Potentiation by potassium iodide using TPPS4 for antimicrobial photodynamic inactivation
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Paper Abstract

Potassium iodide can potentiate antimicrobial photodynamic inactivation (aPDI) of a broad-spectrum of microorganisms, producing many extra logs of killing. We compared two charged porphyrins, TPPS4 (thought to be anionic and not able to bind to Gram-negative bacteria) and TMPyP4 (considered cationic and well able to bind to bacteria). As expected TPPS4 + light did not kill Gram-negative Escherichia coli, but surprisingly when 100 mM KI was added, it was highly effective at mediating aPDI (eradication at 200 nM + 10 J/cm2 of 415 nm light). TPPS4 was more effective than TMPyP4 in eradicating the Gram-positive bacteria, methicillin-resistant Staphylococcus aureus and the fungal yeast Candida albicans (regardless of KI). TPPS4 was also highly active against E. coli after a centrifugation step when KI was added, suggesting that the supposedly anionic porphyrin bound to bacteria and Candida. We conclude that TPPS4 behaves as if it has some cationic character in the presence of bacteria, which may be related to its supply from vendors in the form of a dihydrochloride salt.

Paper Details

Date Published: 8 March 2018
PDF: 9 pages
Proc. SPIE 10479, Light-Based Diagnosis and Treatment of Infectious Diseases, 1047918 (8 March 2018); doi: 10.1117/12.2285246
Show Author Affiliations
Liyi Huang, Guangxi Medical Univ. (China)
Wellman Ctr. for Photomedicine, Massachusetts General Hospital (United States)
Harvard Medical School (United States)
Michael R. Hamblin, Wellman Ctr. for Photomedicine, Massachusetts General Hospital (United States)
Harvard Medical School (United States)
Harvard-MIT Division of Health Sciences and Technology (United States)


Published in SPIE Proceedings Vol. 10479:
Light-Based Diagnosis and Treatment of Infectious Diseases
Tianhong Dai, Editor(s)

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