Aspects of Photodynamic Inactivation of Bacteria

Abstract

Increasing resistance of bacteria to antibiotics is a serious worldwide problem, and to combat resistant bacteria, new antibacterial approaches are to be developed. One alternative to traditional antibiotic therapy is photodynamic antimicrobial chemotherapy (PACT). PACT is based on excitation of photosensitizers (PS) capable of transferring the absorbed light energy to dissolved molecular oxygen causing generation of reactive oxygen species, which irreversibly damage bacterial cell components. The overall efficiency of PACT has been proven for Grampositive and Gram-negative bacteria. The effectiveness of PACT can be increased by encapsulation of PS in liposomes providing more concentrated delivery of PS, enhanced cytotoxicity, improved pharmacokinetic properties, sustained release, and prolonged action of the PS. For continuous and reusable application, PS can be immobilized in polymers. Chemiluminescence, sonodynamic treatment, and radiofrequency irradiation allow to perform excitation of PS in the dark without external illumination, opening prospects for combating internal infections. Combination of PS with antibiotics can gain a synergistic effect, allowing in some cases to overcome the resistance of bacteria to antibiotics.

Physico-Chemical Characterization and Antimicrobial Properties of Hybrid Film Based on Saponite and Phloxine B

“…PhB manifests suitable photoactive properties, absorbing visible light at 540 nm. Moreover, PhB was effective in PDI in the reduction of oral plaques caused by Streptococcus mutans [ 39 ] and Bacillus subtilis [ 40 ]. As it has anionic functional groups, it does not adsorb on layered silicates directly.…”

Antimicrobial Photoinactivation Approach Based on Natural Agents for Control of Bacteria Biofilms in Spacecraft

“…In this context, the antimicrobial photoinactivation (API) approach seems to be one of the most promising strategies. API is a biophotonic technology involving the employment of a photoactive compound (a photosensitizer (PS)) that selectively accumulates in the target cells, which are then illuminated [15,16]. The interaction of the PS and light in the presence of oxygen results in a plethora of cytotoxic reactions.…”

“…Analysis of the literature regarding the application of API to control bacterial biofilms shows that a large number of natural products and their derivatives have significant photodynamic activities, and some of them have been clinically applied. There are several main natural products that can be used in API-some of the most commonly used are curcumin (CUR), riboflavin (RF), perylenequinones (hypericin (Hyp), hypocrellin), psoralens, and chlorophyll derivatives (sodium chlorophyllin (Chl)) [16,18,21]. The emergence of new detection and analysis technologies raises the possibility of the rapid identification of potent PSs derived from natural products, and the extension of the application of already known natural agents.…”

In vitro photodynamic inactivation of B. subtilis and E. coli O157 by a new chalcone conjugate photosensitizer tethered with the NMe 2 group as fluorescence donor auxochrome

“…To increase the e ciency of the PDI, the bioavailability of the PSs within the bacterial cells was improved by penetration enhancers like EDTA [11] and cationic polypeptides that in ict disorganization of the outer membrane in Gram-negative bacteria [21]. As well, the incorporation of the PSs within arti cial liposomes improves their intracellular accumulation and controls their release [22]. The adhesion of porphyrins to bacterial cells and even their endocytosis was modi ed by the glycosylation of pigments such as porphyrins [23].…”