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Photodynamic inactivation of bacteria: Why it is not enough to excite a photosensitizer

Gennady A Meerovich1, Ekaterina V Akhlyustina2, Igor D Romanishkin3

  • 1Prokhorov General Physics Institute of the Russian Academy of Sciences, Moscow 119991, Russia; National Research Nuclear University "MEPhI", Moscow 115409, Russia.

Photodiagnosis and Photodynamic Therapy
|October 20, 2023
PubMed
Abstract

Insights

Antimicrobial photodynamic therapy (APDT) effectively combats multidrug-resistant (MDR) pathogens. Optimizing photosensitizer (PS) design is crucial for successful bacterial inactivation, especially in biofilms.

Area of Science:

  • Microbiology
  • Biophysics
  • Photochemistry

Background:

  • Multidrug resistance (MDR) in infectious agents poses a significant global health threat.
  • Antimicrobial photodynamic therapy (APDT) offers a promising strategy against MDR pathogens and biofilms.

Purpose of the Study:

  • To analyze key approaches for enhancing photosensitizer (PS) efficiency in bacterial photosensitization.
  • To investigate the photodynamic inactivation of bacteria and biofilms using various PS types.

Main Methods:

  • Utilized diverse photosensitizers (PS): methylene blue, phthalocyanines, and bacteriochlorins.
  • Employed LED irradiation for photodynamic inactivation of Gram-positive and Gram-negative bacteria and biofilms.
  • Assessed PS-bacteria interactions via zeta potential, confocal imaging, and coarse-grained modeling.
  • Studied PS aggregation and photobleaching using absorption and fluorescence spectroscopy.

Main Results:

  • Analyzed main strategies for achieving high efficiency in bacterial photosensitization.
  • Evaluated the performance of different PS classes against planktonic bacteria and biofilms.

Conclusions:

  • Photosensitizers (PS) require a balance between cell surface interaction and cell wall penetration.
  • Effective PS must reach intracellular targets without aggregation or photobleaching for optimal photooxidation.
Keywords:
AggregationAntimicrobial photodynamic therapyBacteriaBiofilmElectrostatatic interactionsPhotobleachingPhotodynamic inactivationPhotosensitizerPolycationic

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