Photodynamic inactivation of planktonic and biofilm growing bacteria mediated by a meso-substituted porphyrin bearing four basic amino groups

Abstract

Biofilm-associated diseases account for 80% of all infections in humans. Due to the emergence of antibiotic resistances, alternative therapies such as Photodynamic Inactivation (PDI) of microorganisms have emerged. Porphyrins with intrinsic positive charges have been proposed as successful photosensitizers (PSs) against microorganisms. We have recently designed the new synthetic porphyrin 5,10,15,20-tetrakis[4-(3-N,Ndimethylammoniumpropoxy)phenyl]porphyrin (TAPP) containing four basic amine groups in the periphery of the tetrapyrrolic macrocycle, which can acquire positive charges at physiological pH, thus favouring the interaction with biomembranes. Illumination of planktonic cultures of Staphylococcus aureus at 180 J/cm 2 in the presence of 2.5 µM TAPP induced complete bacteria eradication. For the TAPP-PDI treatment of S. aureus biofilms, higher light fluences and PS concentrations were needed. Employing 20 µM TAPP and 180 J/cm 2 , around 3-log CFU reduction were obtained. In order to determine the efficacy of TAPP-PDI on Gram-negative bacteria, we performed planktonic and biofilm assays employing Pseudomonas aeruginosa. Much higher TAPP doses as compared to S. aureus were needed to achieve planktonic bacteria photosensitization (3-log CFU reduction at 20 µM TAPP and 180 J/cm 2). On the other hand, high concentrations of TAPP were non toxic to P. aeruginosa growing on biofilms, and employing 30 µM TAPP and 180 J/cm 2 we obtained 3-log CFU reduction. The main conclusion of the present work is that TAPP is a promising and efficient PS capable of promoting photodynamic killing of both Gram-negative and-positive in planktonic bacteria, though more effectively in the latter. In addition, TAPP-PDI induces similar photoinactivation rates in both bacteria types growing on biofilms, with lower dark toxicity in the Gram-negative one. Highlights A porphyrin which is charged at physiological pH was used for S. aureus inactivation. Photodynamic treatment induced complete eradication of S. aureus in planktonic state. The same treatment induced 3 logs of CFU reduction of S. aureus biofilms. Gram-positive and-negative bacteria biofilms were equally photosensitized.

Photodynamic inactivation of Listeria innocua biofilms with food-grade photosensitizers: a curcumin-rich extract of Curcuma longa vs commercial curcumin

“…Although causing a less efficient inactivation in relation to CUR, FCRE also caused a significant reduction in the concentration of viable planktonic cells. The lower susceptibility of biofilms is coherent with several literature reports on the comparison of the susceptibility of the planktonic and biofilm forms to PDI (Beirão et al 2014;Mamone et al 2016). Bacterial biofilms are also more resistant to antibiotics and other antimicrobial agents than planktonic cells (Nakamura et al 2013).…”

“…; Mamone et al . ). Bacterial biofilms are also more resistant to antibiotics and other antimicrobial agents than planktonic cells (Nakamura et al .…”

Properties of halogenated and sulfonated porphyrins relevant for the selection of photosensitizers in anticancer and antimicrobial therapies

“…PEG-conjugated photosensitizers, other micellar modification of tetrapyrroles as well as various hybrid materials have also been synthesized and examined in vitro and in vivo for PDT applications [ 37 , 38 ]. The rational design of PS for PDI of microorganisms has been mostly based on the modification of porphyrins [ 5 , 39 ].…”

Photodynamic inactivation to prevent and disrupt Staphylococcus aureus biofilm under different media conditions

“…Comparable results to inactivate S aureus biofilm with different photosensitizers were showed in independent investigation works. The relative photosensitizer 5,10,15,20‐tetrakis[4‐(3‐ N , N dimethylammoniumpropoxy)phenyl] porphyrin (TAPP), which contained the same four basic amine groups in the periphery of the tetrapyrrolic macrocycle as chlorin TAPC, reduce 3 log CFU of S aureus biofilm with the high concentration of 20 μM and 180 J/cm 2 light doses . On the other hand, a large concentration of methylene blue (MB) (50 μM) fail to completely remove S aureus biofilms upon illumination fluence of 22.93 J/cm 2 .…”