Quenching of Singlet Molecular Oxygen (1O2) by Azide Anion in Solvent Mixtures¶

Li, M. Y.; Cline, C. S.; Koker, Edmond B.; Carmichael, Halbert; Chignell, Colin F.; Bilski, Piotr

doi:10.1562/0031-8655(2001)074<0760:qosmoo>2.0.co;2

Cited by 154 publications

(85 citation statements)

References 25 publications

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“…This photo-oxidative mechanism is compatible with the results of photodynamic inactivation experiments performed in the presence of antioxidants. Sodium azide, a wellknown physical quencher of singlet oxygen and inhibitor of PDT cell killing caused by singlet oxygen (Li et al 2001), significantly protected P. aeruginosa cells from the photooxidation induced by GD11 even at the highest light doses tested (114 J cm −2 ), whereas mannitol, a scavenger of free radicals (Tavares et al 2011), did not elicit any effect ( Figure S4). GD11 administered at a concentration of 2.5 μM showed the highest level of photoinactivation in planktonic cultures, but was completely inefficient against biofilms.…”

Section: Discussionmentioning

confidence: 99%

Antimicrobial and anti-biofilm effect of a novel BODIPY photosensitizer againstPseudomonas aeruginosaPAO1

et al. 2014

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Photodynamic therapy (PDT) combines the use of organic dyes (photosensitizers, PSs) and visible light in order to elicit a photo-oxidative stress which causes bacterial death. GD11, a recently synthesized PS belonging to the boron-dipyrromethene (BODIPY) class, was demonstrated to be efficient against planktonic cultures of Pseudomonas aeruginosa, causing a 7 log unit reduction of viable cells when administered at 2.5 μM. The effectiveness of GD11 against P. aeruginosa biofilms grown in flow-cells and microtiter trays was also demonstrated. Confocal laser scanning microscopy of flow-cell-grown biofilms suggests that the treatment has a biocidal effect against bacterial biofilm cells.

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Section: Discussionmentioning

confidence: 99%

Antimicrobial and anti-biofilm effect of a novel BODIPY photosensitizer againstPseudomonas aeruginosaPAO1

et al. 2014

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“…In the presence of 0.1 mM PtPcS and after 24 h of visible light irradiation, we observed very clean type II photooxidation of furfuryl alcohol (30 mM), with formation of the diagnostic products coming from the rearrangement of furfuryl alcohol endoperoxide (Table 1, Figs 7 and 8) [15]; the color of the sensitizer turned green, in agreement with the decreased intensity and the red shift of the Q band. In the presence of sodium azide, a strong singlet oxygen quencher [16], endoperoxide formation was totally suppressed and the reaction mixtures fully preserved their initial blue color. RuPcS behaved differently: we noticed weak NMR signals, attributable to the rearranged endoperoxide products, even if the relative amounts were extremely small (less than 5% with respect to the conversion of furfuryl alcohol).…”

Section: Resultsmentioning

confidence: 99%

“…calcd. for C 36 H 16 RuPcC. The same procedure as above was carried out except for the metal salt which was RuCl 3 ·nH 2 O instead of K 2 PtCl 4 (only one molecule of H 2 O was considered in the molecular weight).…”

Section: Synthesis Of Metal Phthalocyaninesmentioning

confidence: 99%

Visible photostability of some ruthenium and platinum phthalocyanines in water and in the presence of organic substrates

Carchesio

Tonucci

d’Alessandro

et al. 2010

J. Porphyrins Phthalocyanines

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Water-soluble, metal-tetrasubstituted phthalocyanines (-SO 3 H, MPcS and -COOH, MPcC) of platinum and ruthenium were synthesized and their photostability to visible light irradiation was determined. For the ruthenium phthalocyanines, the characteristic visible Q band of the phtha locyanines was almost totally suppressed after five days of irradiation. The platinum derivatives were instead more resistant to photodegradation, and the Q band did not decrease by more than 25%. The addition of carbonyl compounds to the phthalocyanine solution in water (at concentrations at least 1400-fold those of the phthalocyanines) dramatically accelerated the photobleaching of these phthalocyanine complexes. PtPcS turned from blue to green and to colorless with one day of visible-light irradiation in the presence of acetone. This effect decreased with the increase in molecular weight of the ketones (from acetone to 2-pentanone). The addition of alcohols (i.e. 1-butanol) or other organics (i.e. phenylacetic acid) did not affect the photostability of these metal-tetrasubstituted phthalocyanines. Dioxygen also had an important role, as when the solutions of phthalocyanines were carefully deaerated before irradiation, the visible spectra were preserved. The platinum phthalocyanines, as with the palladium analogs, sensitize the photoproduction of 1 O 2 , as shown by the formation of endoperoxide and its rearranged products in the presence of furfuryl alcohol (a singlet oxygen trapping agent).

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“…In that study, they used two different PS: MB (type I mechanism) and polyethylenimine-chlorin (e6) (PEI-ce6) conjugate (type II mechanism) expecting to see quenching of killing by NaN 3 . NaN 3 is well known as a physical quencher of 1 O 2 [182] and has been widely employed to quench singlet oxygen during aPDI [183]. They observed that addition of NaN 3 (100 μm or 10 mm) to Gram-negative E. coli and Gram-positive S. aureus incubated with MB and illuminated with red light gave significantly increased bacterial killing (1–3 logs), rather than the expected protection from killing.…”

Section: Methods Of Potentiating Apdimentioning

confidence: 99%

Advances in antimicrobial photodynamic inactivation at the nanoscale

2017

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The alarming worldwide increase in antibiotic resistance amongst microbial pathogens necessitates a search for new antimicrobial techniques, which will not be affected by, or indeed cause resistance themselves. Light-mediated photoinactivation is one such technique that takes advantage of the whole spectrum of light to destroy a broad spectrum of pathogens. Many of these photoinactivation techniques rely on the participation of a diverse range of nanoparticles and nanostructures that have dimensions very similar to the wavelength of light. Photodynamic inactivation relies on the photochemical production of singlet oxygen from photosensitizing dyes (type II pathway) that can benefit remarkably from formulation in nanoparticle-based drug delivery vehicles. Fullerenes are a closed-cage carbon allotrope nanoparticle with a high absorption coefficient and triplet yield. Their photochemistry is highly dependent on microenvironment, and can be type II in organic solvents and type I (hydroxyl radicals) in a biological milieu. Titanium dioxide nanoparticles act as a large band-gap semiconductor that can carry out photo-induced electron transfer under ultraviolet A light and can also produce reactive oxygen species that kill microbial cells. We discuss some recent studies in which quite remarkable potentiation of microbial killing (up to six logs) can be obtained by the addition of simple inorganic salts such as the non-toxic sodium/potassium iodide, bromide, nitrite, and even the toxic sodium azide. Interesting mechanistic insights were obtained to explain this increased killing.

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Quenching of Singlet Molecular Oxygen (1O2) by Azide Anion in Solvent Mixtures¶

Cited by 154 publications

References 25 publications

Antimicrobial and anti-biofilm effect of a novel BODIPY photosensitizer againstPseudomonas aeruginosaPAO1

Antimicrobial and anti-biofilm effect of a novel BODIPY photosensitizer againstPseudomonas aeruginosaPAO1

Visible photostability of some ruthenium and platinum phthalocyanines in water and in the presence of organic substrates

Advances in antimicrobial photodynamic inactivation at the nanoscale

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