The application of antimicrobial photodynamic therapy on S. aureus and E. coli using porphyrin photosensitizers bound to cyclodextrin

Abstract

Photodynamic therapy is usually used against malignant and non-malignant tumors. Nowadays, due to resistance of bacterial strains, we are looking for a new antimicrobial strategy to destroy bacteria with minimal invasive consequences. The worldwide increase in antibiotic resistance among different classes of gram-positive and gram-negative bacteria has led to the search for alternative anti-microbial therapies such as antimicrobial PDT (aPDT). Development antimicrobial technology combines a nontoxic compound, called photosensitizer, visible light of the appropriate wavelength, and the generation of reactive oxygen species. In this work, the photosensitizers TMPyP and ZnTPPS4 are investigated for photodynamic and antimicrobial photodynamic therapy. We tested these two porphyrins on two cell lines and two bacterial strains to compare effectiveness. In addition, we applied photosensitizers bound in the complex created with hp-β-cyclodextrin. The light-emitting diodes were used at the doses 0, 1, 5, 10 J/cm(2) for cells and 0, 150 J/cm(2) for bacteria. Tested concentrations for cells and microbes were from 0.5 to 50 μM and from 0.78 to 100 μM, respectively. From this work it can be concluded that TMPyP is a promising compound both in aPDT and in PDT, particularly in contrast to ZnTPPS4, which was efficient only in PDT. Furthermore, the eradication of gram-positive bacteria is possible only with higher concentrations of ZnTPPS4.

Glycosylated Porphyrins, Phthalocyanines, and Other Porphyrinoids for Diagnostics and Therapeutics

“…Several porphyrin and Pc-based PSs are reported to be effective for the photodynamic inactivation (PDI) of bacteria and viruses. 99–106 The work reported so far is promising for the deployment of novel glycosylated porphyrinoids to obtain therapies with a large spectrum of antibacterial activity.…”

Photodynamic antimicrobial chemotherapy with the novel amino acid-porphyrin conjugate 4I: In vitro and in vivo studies

“…On the other hand, biofilm formation could lead to reduce susceptibility to photoinactivation [26]. ROS are formed after non-toxic photosensitizers are actived by irradiation with laser through either electron transfer (type I) or energy transfer (type II) mechanisms, which can react with many cellular components (cytoplasmic membrane, DNA/RNA, amino acids, unsaturated lipids and so on) and then cause leakage of cellular contents or inactivation of membrane transport systems and enzymes and last induce lethal damage to bacteria [30, 31]. Moreover, our colleague verified and validated the photoinactivation mechanism of 4I mediated PACT against MRSA, P .…”

“…The cell viability decreased as 4I concentrations increased to or over 3.9 μM, which could be ascribed to the production of ROS. It have been proved that low concentration of ROS is essential for normal cellular processes, while high levels can induce deleterious effects on cells [30, 34]. Once increasing the PS concentration, the amount of PS bound to each cell increases; otherwise, photodynamic effects have a strong connection with photosensitizer binding due to the generation of ROS in situ [35].…”

Antibacterial photodynamic therapy: overview of a promising approach to fight antibiotic-resistant bacterial infections

“…A cationic charge is a critical factor in APDT of Gram-positive species. Porphyrins with a net cationic charge, such as meso-substituted cationic porphyrins, effectively kill Gram-negative bacteria because of increased binding/uptake efficacy [38]. Corroboratively, two novel cationic porphyrins carrying pyridinium (PyP, Table 1) and imidazolium (ImP) substituents were shown to bind different loci at the bacterial outer membrane via ionic interactions, penetrate the cell wall, and enter the cell [39].…”