Photosensitizing activity of water- and lipid-soluble phthalocyanines on Escherichia coli

Abstract

Escherichia coli, as most Gram‐negative bacteria, is insensitive to the photosensitizing action of both lipid‐soluble Zinc‐phthalocyanine (Zn‐Pc) and water‐soluble Zinc‐mono/disulfonated phthalocyanine (Zn‐PcS). Photosensitivity can be induced by alteration of the outer membrane, as obtained by either induction of competence or treatment with Tris‐EDTA. Both phthalocyanines largely bind at the level of the cytoplasmic membrane; however, Zn‐PcS shows a superior photosensitizing activity as compared with Zn‐Pc. Biochemical analyses performed on irradiated cells suggest that the cytoplasmic membrane is an important target of the photoprocess, while DNA is not involved.

Photodestruction of human dental plaque bacteria: Enhancement of the photodynamic effect by photomechanical waves in an oral biofilm model

“…Several studies have demonstrated that Gram-positive bacteria are susceptible to photoinactivation [27][28][29]. On the other hand, Gram-negative bacteria have been resistant to photodynamic action [27,30], unless the permeability of their outer membrane is modified by Tris/EDTA [31] or polymyxin B nonapeptide [32].…”

“…On the other hand, Gram-negative bacteria have been resistant to photodynamic action [27,30], unless the permeability of their outer membrane is modified by Tris/EDTA [31] or polymyxin B nonapeptide [32]. Gram-negative species have shown enhanced susceptibility to photodynamic action following the application of a PS with cationic charge [33,34] including cationic phenothiazines such as toluidine blue O and methylene blue [35][36][37].…”

An in vitro study of the photodynamic effect of rose bengal on trichophyton rubrum

“…They are chosen on the basis of their charge, ability to be non-toxic without illumination (dark toxicity) and the ability to become genotoxic or mutagenic following irradiation [23]. Rose Bengal (RB) is a photosensitizer that has been found to be toxic to various microbes, including Streptococcus mutans and Candida albicans, when used with PDT [24,25].…”

Photobiological activity of exogenous and endogenous porphyrin derivatives in Escherichia coli and Enterococcus hirae cells

“…the combined use of photosensitisers and visible light, is considered to be a new potential method for inactivation of microorganisms [1,2,3,4], in the context of the disinfection of water, blood and blood products [5]. A number of photosensitisers are known to be phototoxic towards a variety of Gram-positive bacteria, mycoplasma and yeast [2,6,7]. However, Gram-negative bacteria have not usually been susceptible to photosensitising effects, unless the permeability of their membranes has been artificially increased [8,9].…”

“…Photodynamic treatment, i.e. the combined use of photosensitisers and visible light, is considered to be a new potential method for inactivation of microorganisms [1,2,3,4], in the context of the disinfection of water, blood and blood products [5]. A number of photosensitisers are known to be phototoxic towards a variety of Gram-positive bacteria, mycoplasma and yeast [2,6,7].…”