Applications of Antimicrobial Photodynamic Therapy against Bacterial Biofilms

Abstract

Antimicrobial photodynamic therapy and allied photodynamic antimicrobial chemotherapy have shown remarkable activity against bacterial pathogens in both planktonic and biofilm forms. There has been little or no resistance development against antimicrobial photodynamic therapy. Furthermore, recent developments in therapies that involve antimicrobial photodynamic therapy in combination with photothermal hyperthermia therapy, magnetic hyperthermia therapy, antibiotic chemotherapy and cold atmospheric pressure plasma therapy have shown additive and synergistic enhancement of its efficacy. This paper reviews applications of antimicrobial photodynamic therapy and non-invasive combination therapies often used with it, including sonodynamic therapy and nanozyme enhanced photodynamic therapy. The antimicrobial and antibiofilm mechanisms are discussed. This review proposes that these technologies have a great potential to overcome the bacterial resistance associated with bacterial biofilm formation.

Keywords: antibiotic chemotherapy; antimicrobial photodynamic therapy; biofilm; cold atmospheric pressure plasma; extracellular polymeric substance; magnetic hyperthermia therapy; nanozyme enhanced photodynamic therapy; photothermal hyperthermia therapy; planktonic bacteria; sonodynamic therapy.

Figure 1

Jablonski diagram to illustrate the aPDT type I and II mechanisms.

Figure 2

Illustration of the triple therapy combination of PTT, PDT, and nanozyme effect of molybdenum trioxide nanoparticles.

Figure 3

Chemical structures of sinoporphyrin sodium (a) and protoporphyrin IX (b).

Figure 4

Illustration of the Fenton reaction-enhanced SDT, a combination of SDT with the Fenton reaction generation of hydroxyl radicals (Guo et al., 2021) [152].

Figure 5

The self-assembly nanozyme formation mechanism and the planktonic bacterial cell aggregation mechanism leading to photodynamic bacterial cell death and biofilm structure destruction. (a) Bipyridine mediated self-assembly of the porphyrins to form the porphyrin nanozyme with peroxidase/catalase mimic activities. (b) Planktonic cell aggregation mechanism reported by Hu et al. (2022) [163]. (1) planktonic microbial form, (2) surface adhesion, (3) colony formation and maturation, (4) biofilm formation, (5) microbial detachment from biofilm.

Figure 6

Nanozyme, photothermal, photodynamic, and glutathione oxidation activity of molybdenum disulfide sheet conjugated UIO-66 metal-organic-framework [167].