Mechanistic and Kinetic Aspects of Photosensitization in the Presence of Oxygen †§

Taniélian, Charles; Méchin, Robert; Seghrouchni, Rachid; Schweitzer, Claude

doi:10.1562/0031-8655(2000)0710012makaop2.0.co2

Cited by 18 publications

(16 citation statements)

References 49 publications

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“…Photons excite the PS to the highly unstable singlet state, which then shifts to the long-lived triplet state before transferring electrons to organic molecules or energy to molecular oxygen, respectively producing free radicals (type I mechanism) or singlet oxygen ( 1 O 2 -type II mechanism) [2][3][4]. These highly reactive species are antibacterial because they irreversibly damage proteins, membrane lipids and DNA [1].…”

Section: Introductionmentioning

confidence: 99%

Rose bengal uptake by E. faecalis and F. nucleatum and light-mediated antibacterial activity measured by flow cytometry

Manoil

Filieri

Schrenzel

et al. 2016

Journal of Photochemistry and Photobiology B: Biology

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Rose bengal uptake by E. faecalis and F. nucleatum and light-mediated antibacterial activity measured by flow cytometry Antibacterial photodynamic therapy (aPDT) using rose bengal (RB) and blue-light kills bacteria through the production of reactive oxygen derivates. However, the interaction mechanism of RB with bacterial cells remains unclear. This study investigated the uptake efficiency and the antibacterial activity of blue light-activated RB against Enterococcus faecalis and Fusobacterium nucleatum. Spectrophotometry and epifluorescence microscopy were used to evaluate binding of RB to bacteria. The antibacterial activity of RB after various irradiation times was assessed by flow cytometry in combination with cell sorting. Uptake of RB increased in a concentration dependent manner in both strains although E. faecalis displayed higher uptake values. RB appeared to bind specific sites located at the cellular poles of E. faecalis and at regular intervals along F. nucleatum. Blue-light irradiation of samples incubated with RB significantly reduced bacterial viability. After incubation with 10 μM RB and 240 s irradiation, only 0.01% (± 0.01%) of E. faecalis cells and 0.03% (±0.03%) of F. nucleatum survived after treatment. This study indicated that RB can bind to E. faecalis and F. nucleatum in a sufficient amount to elicit effective aPDT. Epifluorescence microscopy showed a yet-unreported property of RB binding to bacterial membranes. Flow cytometry allowed the detection of bacteria with damaged membranes that were unable to form colonies on agars after cell sorting.

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Section: Introductionmentioning

confidence: 99%

Rose bengal uptake by E. faecalis and F. nucleatum and light-mediated antibacterial activity measured by flow cytometry

Manoil

Filieri

Schrenzel

et al. 2016

Journal of Photochemistry and Photobiology B: Biology

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“…The ability of PDT to produce ROS needs the presence of molecular oxygen (O 2 ; Foote, 1991; Tanielian et al, 2000). As mentioned above, the ground electronic state of oxygen is a triplet, whereby the two outermost orbitals are unpaired but spin parallel and this triplet can undergo energy transfer upon collision with the excited PS triplet.…”

Section: Introductionmentioning

confidence: 99%

Concepts and Principles of Photodynamic Therapy as an Alternative Antifungal Discovery Platform

Dai¹,

Fuchs²,

Coleman³

et al. 2012

Front. Microbio.

221

137

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Opportunistic fungal pathogens may cause superficial or serious invasive infections, especially in immunocompromised and debilitated patients. Invasive mycoses represent an exponentially growing threat for human health due to a combination of slow diagnosis and the existence of relatively few classes of available and effective antifungal drugs. Therefore systemic fungal infections result in high attributable mortality. There is an urgent need to pursue and deploy novel and effective alternative antifungal countermeasures. Photodynamic therapy (PDT) was established as a successful modality for malignancies and age-related macular degeneration but photodynamic inactivation has only recently been intensively investigated as an alternative antimicrobial discovery and development platform. The concept of photodynamic inactivation requires microbial exposure to either exogenous or endogenous photosensitizer molecules, followed by visible light energy, typically wavelengths in the red/near infrared region that cause the excitation of the photosensitizers resulting in the production of singlet oxygen and other reactive oxygen species that react with intracellular components, and consequently produce cell inactivation and death. Antifungal PDT is an area of increasing interest, as research is advancing (i) to identify the photochemical and photophysical mechanisms involved in photoinactivation; (ii) to develop potent and clinically compatible photosensitizers; (iii) to understand how photoinactivation is affected by key microbial phenotypic elements multidrug resistance and efflux, virulence and pathogenesis determinants, and formation of biofilms; (iv) to explore novel photosensitizer delivery platforms; and (v) to identify photoinactivation applications beyond the clinical setting such as environmental disinfectants.

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“…When the PS is in the long-lived triplet state, it may interact with O 2 in two distinctly different ways. 17,18 The Type I process occurs when the PS directly transfers an electron, sometimes in concert with proton donation, to O 2 , yielding superoxide anion (O 2…”

Section: The Photochemical Generation Of Oxidizing Speciesmentioning

confidence: 99%

All you need is light

et al. 2011

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Mechanistic and Kinetic Aspects of Photosensitization in the Presence of Oxygen †§

Cited by 18 publications

References 49 publications

Rose bengal uptake by E. faecalis and F. nucleatum and light-mediated antibacterial activity measured by flow cytometry

Rose bengal uptake by E. faecalis and F. nucleatum and light-mediated antibacterial activity measured by flow cytometry

Concepts and Principles of Photodynamic Therapy as an Alternative Antifungal Discovery Platform

All you need is light

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