Synergetic antimicrobial effect of chlorin e6 and hydrogen peroxide on multi-species biofilms

Min Nie, Rodrigo Costa e. Silva, Kleber Thiago de Oliveira, Vanderlei Salvador Bagnato, Alessandra Nara de Souza Rastelli, Wim Crielaard, Jingmei Yang*, Dong Mei Deng

*Corresponding author for this work

Research output: Contribution to JournalArticleAcademicpeer-review


Antimicrobial photodynamic therapy (aPDT) has been considered as a potential alternative to antibiotics for the treatment of biofilm infections. There is evidence that an additional H2O2 enhances the antimicrobial efficacy of aPDT. However, the minimum H2O2 concentration to achieve this synergistic effect is unclear. A saliva-derived multi-species biofilm was treated with the photosensitizer chlorin e6 (Ce6, 50 µM), H2O2 (0.3, 3.3, 33.3 mM), or their combination for 5 min, followed by no irradiation or irradiation at 15 J (cm2)−1 (λ = 450 nm or 660 nm), with or without oxygen. Biofilm viability and metabolic activity were evaluated. The combination of 33.3 mM H2O2 and Ce6-aPDT strongly enhanced antimicrobial efficacy compared with either component alone, irrespective of oxygen availability and irradiation wavelength. In particular, the combination resulted in a 6.6-log colony forming unit (CFU) reduction anaerobically under blue irradiation. This combination is a promising treatment for biofilm infections, especially those thriving in an anaerobic microenvironment.

Original languageEnglish
Pages (from-to)656-665
Number of pages10
Issue number6
Early online date26 Jul 2021
Publication statusPublished - 2021

Bibliographical note

Funding Information:
This work was supported by the Research and Development Foundation of the West China Hospital of Stomatology, Sichuan University (No. RD-02-201905). The authors thank Paul W. Bible from the College of Arts and Sciences of Marian University in Indianapolis, Indiana, for language editing.

Publisher Copyright:
© 2021 Informa UK Limited, trading as Taylor & Francis Group.


  • biofilm
  • chlorin e6
  • hydrogen peroxide
  • oxygen
  • Photodynamic therapy


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