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Cationic Phenosafranin Photosensitizers Based on Polyhedral Oligomeric Silsesquioxanes for Inactivation of

Krystyna Rozga-Wijas1, Irena Bak-Sypien1, Katarzyna Turecka2

  • 1Centre of Molecular and Macromolecular Studies, Polish Academy of Science, Sienkiewicza 112, 90-363 Lodz, Poland.

International Journal of Molecular Sciences
|December 24, 2021
PubMed

Insights

New cationic phenosafranin polyhedral oligomeric silsesquioxane (POSS) conjugates demonstrate potent photodynamic antibacterial effects against Staphylococcus aureus and E. coli. These novel POSS-photosensitizers achieve bacterial eradication at low concentrations upon light activation.

Area of Science:

  • Materials Science
  • Nanotechnology
  • Photochemistry
  • Antimicrobial Agents

Background:

  • Development of novel antimicrobial strategies is crucial to combat antibiotic-resistant bacteria.
  • Photodynamic therapy (PDT) offers a light-activated approach to bacterial killing.
  • Polyhedral oligomeric silsesquioxanes (POSS) are versatile inorganic nanostructures with tunable properties.

Purpose of the Study:

  • To synthesize and characterize novel cationic light-activated phenosafranin polyhedral oligomeric silsesquioxane (POSS) conjugates.
  • To evaluate the in vitro photodynamic antibacterial efficacy of these POSS conjugates against Staphylococcus aureus and Escherichia coli.
  • To investigate the cellular localization and mechanism of bacterial eradication.

Main Methods:

  • Synthesis of water-soluble POSS-photosensitizers by chemically coupling phenosafranin dye (PSF) to POSS cages.
  • Structural characterization using NMR, HRMS, IR, fluorescence, and UV-VIS spectroscopy.
  • In vitro antibacterial assays involving light irradiation, confocal microscopy, and transmission electron microscopy (TEM).

Main Results:

  • High photodynamic antibacterial effect observed for POSS-PSF conjugates against S. aureus and E. coli.
  • Bacterial eradication achieved at low POSS concentrations (0.38 µM) after 5 min of light irradiation.
  • TEM revealed ruptured bacterial cells, indicating membrane damage and cytosolic leakage.
  • Confocal microscopy showed intracellular accumulation of POSSPSF and cell wall/membrane accumulation of POSSPSFDAU.

Conclusions:

  • Cationic phenosafranin POSS conjugates are effective photosensitizers for photodynamic antibacterial therapy.
  • The conjugates eradicate bacteria via reactive oxygen species (ROS) production, leading to oxidative damage of cellular components.
  • These findings highlight the potential of POSS-based nanomaterials as novel antimicrobial agents.
Keywords:
E. coliPOSS conjugateROSantibacterial photodynamic inactivationbacterial infectious diseaseclinical isolates S. aureusdaunorubicindrug resistancephenazinum dyephenosafranin photosensitizersilsesquioxanevesicularization

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