Photoinactivation of Pseudomonas aeruginosa Biofilm by Dicationic Diaryl-Porphyrin

Abstract

In recent years, antimicrobial photodynamic therapy (aPDT) has received increasing attention as a promising tool aimed at both treating microbial infections and sanitizing environments. Since biofilm formation on biological and inert surfaces makes difficult the eradication of bacterial communities, further studies are needed to investigate such tricky issue. In this work, a panel of 13 diaryl-porphyrins (neutral, mono- and di-cationic) was taken in consideration to photoinactivate Pseudomonas aeruginosa. Among cationic photosensitizers (PSs) able to efficiently bind cells, in this study two dicationic showed to be intrinsically toxic and were ruled out by further investigations. In particular, the dicationic porphyrin (P11) that was not toxic, showed a better photoinactivation rate than monocationic in suspended cells. Furthermore, it was very efficient in inhibiting the biofilms produced by the model microorganism Pseudomonas aeruginosa PAO1 and by clinical strains derived from urinary tract infection and cystic fibrosis patients. Since P. aeruginosa represents a target very difficult to inactivate, this study confirms the potential of dicationic diaryl-porphyrins as photo-activated antimicrobials in different applicative fields, from clinical to environmental ones.

Gallium Protoporphyrin Liquid Crystalline Lipid Nanoparticles: A Third-Generation Photosensitizer against Pseudomonas aeruginosa Biofilms

“…The antibacterial photodynamic activity of GaPP and GaPP-LCNP was evaluated against P . aeruginosa (PAO1) in planktonic culture, as previously reported [ 17 , 18 ] with appropriate modifications. Briefly, an overnight culture of P .…”

Photodynamic Inactivation of Opportunistic Premise Plumbing Pathogens and Their Biofilms

“…On the other hand, strong binding can have negative consequences, as seen among the 13 diaryl-porphyrins (neutral, mono-and di-cationic) tested on P. aeruginosa; it turned out, as expected, that all the cationic ones strongly bind to the bacterial cell, but some of them were intrinsically toxic and were thus excluded from further studies [137]. A cationic porphyrin that did not show intrinsic toxicity, dicationic diaryl porphyrin with two benzyl groups attached to nitrogen atoms of two pyridyl substituents on the porphyrin, was chosen as the most promising against P. aeruginosa PAO1 biofilm [137]. This PS was applied with blue light (410 nm; 30 J/cm 2 ) against biofilms formed by two clinical isolates, among which BT1 clinical isolate formed a biofilm with very high biomass value, and the PS inhibited biomass adhesion for all tested strains [137].…”

“…A cationic porphyrin that did not show intrinsic toxicity, dicationic diaryl porphyrin with two benzyl groups attached to nitrogen atoms of two pyridyl substituents on the porphyrin, was chosen as the most promising against P. aeruginosa PAO1 biofilm [137]. This PS was applied with blue light (410 nm; 30 J/cm 2 ) against biofilms formed by two clinical isolates, among which BT1 clinical isolate formed a biofilm with very high biomass value, and the PS inhibited biomass adhesion for all tested strains [137]. Together with light, the PS caused a significant reduction of the adherent population and biomass, as well as planktonic population, while for the mature biofilm (24 h old), there was a mild effect (2-log reduction) on all cells in the biofilm [137].…”

Photodynamic Inactivation of Legionella pneumophila Biofilm Formation by Cationic Tetra- and Tripyridylporphyrins in Waters of Different Hardness

“…Porphyrin PSs have been widely tested in the treatment of Pseudomonas aeruginosa, another Gram-negative OPPP. Orlandi et al recently tested the effects of a group of 13 diaryl porphyrins on biofilm formation and eradication of biofilm mass [36]. It was shown that diaryl porphyrins bearing two positively charged pyridyl groups on the opposite side of the porphyrin core have the highest antibiofilm properties and can inhibit the biofilm formation and have a mild effect on the formed biofilm [36].…”

“…Orlandi et al recently tested the effects of a group of 13 diaryl porphyrins on biofilm formation and eradication of biofilm mass [36]. It was shown that diaryl porphyrins bearing two positively charged pyridyl groups on the opposite side of the porphyrin core have the highest antibiofilm properties and can inhibit the biofilm formation and have a mild effect on the formed biofilm [36]. The authors presumed that the highest antibiofilm properties are due to the positive charge of the pyridyl groups being delocalized and directly coordinated with the tetrapyrrole system of porphyrin.…”