Photosensitization of Wild and Mutant Strains ofEscherichia colibymeso-Tetra (N-methyl-4-pyridyl)porphine

Valduga, Giuliana; Breda, B.; Giacometti, Giorgio M.; Jori, Giulio; Reddi, Elena

doi:10.1006/bbrc.1999.0190

Cited by 70 publications

(53 citation statements)

References 18 publications

Supporting

Mentioning

Contrasting

Unclassified

Order By: Relevance

“…-Several enzymes, which are associated with the cytoplasmic side of the S. aureus membrane, such as NADH, lactate or succinic dehydrogenase, are photoinactivated by phthalocyanines at a rate which closely corresponds with the rate of photoinduced cell death [70]. Similarly, several outer membrane and plasma membrane proteins undergo an extensive cross-linking in the early stages of phenothiazine photosensitization of Porphyromonas gingivalis [71] and cationic porphyrin photosensitization of E. coli [72]. -A loss of membrane barrier properties resulting in the leakage of intracellular contents, including a collapse of K þ and ionic balance, represents an important step for loss of clonogenicity in photosensitized bacteria and yeasts, such as S. aureus [73] and, respectively, Kluyveromyces marxianus [74].…”

Section: Photodynamic Inactivation Of Microbial Cells: In Vitro Studiesmentioning

confidence: 99%

“…-A loss of membrane barrier properties resulting in the leakage of intracellular contents, including a collapse of K þ and ionic balance, represents an important step for loss of clonogenicity in photosensitized bacteria and yeasts, such as S. aureus [73] and, respectively, Kluyveromyces marxianus [74]. Membrane damage is also responsible for the rapid impairment of transport functions in bacteria [72] and yeasts [75]; in general, the photoprocess causes a massive reduction in the transport capacity of a wide variety of solutes, thus leading to a shortage of essential substrates for anabolic and catabolic pathways and providing an important contribution to the drop of cell viability.…”

Section: Photodynamic Inactivation Of Microbial Cells: In Vitro Studiesmentioning

confidence: 99%

“…As a consequence, a variety of targets, including DNA, undergo photooxidative modification at later stages of the overall photoprocess, even though such damage is not directly correlated with cell death [24,69,75,78,80]. Thus, any major influence of DNA modification seems unlikely since (a) Deinococcus radiodurans, which possesses a very efficient DNA repair mechanism, is readily killed by photodynamic processes [81]; and (b) wild E. coli strains, as well as E. coli strains which are defective for DNA repair mechanisms, display a closely similar sensitivity to photoinactivation by a tetracationic porphyrin [72]. This pattern of cellular photomodification is in agreement with the repeatedly observed lack of mutagenic effects induced by photosensitization of microbial cells by porphyrin-type or phenothiazine derivatives [17,43,52].…”

Section: Photodynamic Inactivation Of Microbial Cells: In Vitro Studiesmentioning

confidence: 99%

See 2 more Smart Citations

Photodynamic therapy in the treatment of microbial infections: Basic principles and perspective applications

et al. 2006

Self Cite

View full text Add to dashboard Cite

Background and Objectives: Photodynamic therapy (PDT) appears to be endowed with several favorable features for the treatment of infections originated by microbial pathogens, including a broad spectrum of action, the efficient inactivation of antibiotic-resistant strains, the low mutagenic potential, and the lack of selection of photoresistant microbial cells. Therefore, intensive studies are being pursued in order to define the scope and field of application of this approach. Results: Optimal cytocidal activity against a large variety of bacterial, fungal, and protozoan pathogens has been found to be typical of photosensitizers that are positively charged at physiological pH values (e.g., for the presence of quaternarized amino groups or the association with polylysine moieties) and are characterized by a moderate hydrophobicity (n-octanol/water partition coefficient around 10). These photosensitizers in a micromolar concentration can induce a > 4-5 log decrease in the microbial population after incubation times as short as 5-10 minutes and irradiation under mild experimental conditions, such as fluence-rates around 50 mW/cm 2 and irradiation times shorter than 15 minutes. Conclusions: PDT appears to represent an efficacious alternative modality for the treatment of localized microbial infections through the in situ application of the photosensitizer followed by irradiation of the photosensitizer-loaded infected area. Proposed clinical fields of interest of antimicrobial PDT include the treatment of chronic ulcers, infected burns, acne vulgaris, and a variety of oral infections.

show abstract

Section: Photodynamic Inactivation Of Microbial Cells: In Vitro Studiesmentioning

confidence: 99%

Section: Photodynamic Inactivation Of Microbial Cells: In Vitro Studiesmentioning

confidence: 99%

Section: Photodynamic Inactivation Of Microbial Cells: In Vitro Studiesmentioning

confidence: 99%

See 1 more Smart Citation

Photodynamic therapy in the treatment of microbial infections: Basic principles and perspective applications

et al. 2006

Self Cite

View full text Add to dashboard Cite

show abstract

“…We incubated S. aureus or E. coli with 100 mM TMPyP for 60 min, which can yield a killing efficacy of 99.99% upon radiant exposure [11,12,30]. At first, incubated bacteria in suspension were placed under the fluorescence microscope.…”

Section: Aqueous Suspension Of Bacteria Incubated With the Photosensimentioning

confidence: 99%

A helpful technology – the luminescence detection of singlet oxygen to investigate photodynamic inactivation of bacteria (PDIB)

Regensburger

Maisch

Felgenträger

et al. 2010

Journal of Biophotonics

View full text Add to dashboard Cite

Photodynamic inactivation of bacteria (PDIB) is considered a new approach for the struggle against multiresistant bacteria. To achieve a sufficient level of bacteria killing, the photosensitizer must attach to and/or penetrate the bacteria and generate a sufficiently high amount of singlet oxygen. To optimize PDIB, the direct detection and quantification of singlet oxygen in bacteria is a helpful tool. Singlet-oxygen luminescence is a very weak signal, in particular in living bacteria. We first performed experiments in aqueous photosensitizer solution to optimize the luminescence system. We eliminated non-singlet-oxygen photons, which is important for the quantification of singlet oxygen and its rise and decay rates. This procedure is even more important when the laser excitation beam is scattered by bacteria (diameter 1 microm). In suspensions with both Gram-positive and Gram-negative bacteria we then clearly detected singlet oxygen by its luminescence and determined the respective rise and decay times. The decay times should provide an indication of localization of singlet oxygen and hence of the photosensitizer even in small bacteria.

show abstract

“…Previous studies [25][26][27] have shown that while it works well for Gram-positive bacteria, with only a few exceptions photodynamic inactivation is ineffective in eradicating Gram-negative bacteria as a result of their additional outer layer of cell wall. It is so unless the bacteria are treated with reagents such as ethylenediaminetetraacetic acid (EDTA) or polymyxin nonapeptide (PMNP) to alter the permeability of the bacterial outer membrane before photosensitization [28,29], or a cationic photosensitizer was employed instead [30].…”

Section: Bacterial Strainmentioning

confidence: 99%

Evaluation of the Practicality of Melanin as a Photodynamic-Inactivation Photosensitizer by Its Nanonization

Liu

Lin

2015

J. Photopol. Sci. Technol.

View full text Add to dashboard Cite

It has been proposed that melanin may play a role in the antimicrobial defense system of a human body. Furthermore, it has been found that melanin has efficacy against oxidative stress, tumor, venin, virus, and heavy metal ions. In view of the great potential of melanin in medical applications revealed by its photodynamic actions, we develop techniques based on mechanical stir and photo-fragmentation with femtosecond laser pulses respectively for nanonization of melanin to produce nanometer-sized and water-dispersible melanin, in order to more reliably study melanin as a photodynamic-inactivation photosensitizer. In vitro experiments on the antimicrobial efficacy of nanonized melanin were conducted. It was found that both Sepia melanin and synthetic melanin do not have a significant effect on lowering the survival rate of Gram-positive bacteria Streptococcus mutans with or without light irradiation. Therefore, it is concluded that melanin, though capable of generating melanin radicals and reactive oxygen species, is not a practical agent for photodynamic inactivation.

show abstract

Photosensitization of Wild and Mutant Strains ofEscherichia colibymeso-Tetra (N-methyl-4-pyridyl)porphine

Cited by 70 publications

References 18 publications

Photodynamic therapy in the treatment of microbial infections: Basic principles and perspective applications

Photodynamic therapy in the treatment of microbial infections: Basic principles and perspective applications

A helpful technology – the luminescence detection of singlet oxygen to investigate photodynamic inactivation of bacteria (PDIB)

Evaluation of the Practicality of Melanin as a Photodynamic-Inactivation Photosensitizer by Its Nanonization

Contact Info

Product

Resources

About