Optical determination of the rates of formation and decay of O2(1Δg) in H2O, D2O and other solvents

Parker, J. G.; Stanbro, W.D.

doi:10.1016/0047-2670(84)87054-9

Cited by 39 publications

(26 citation statements)

References 5 publications

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“…Direct detection as described in previous papers was done by time resolved measurements at 1270 nm (10 nm FWHM filter) in near-backward direction with respect to the exciting beam using an infrared-sensitive photomultiplier (R5509-42, Hamamatsu Photonics Deutschland GmbH, Herrsching, Germany). The luminescence intensity is given by

\begin{matrix} I (t) = \frac{c}{t_{R}^{- 1} - t_{D}^{- 1}} [\exp (- \frac{t}{t_{D}}) - \exp (- \frac{t}{t_{R}})], \end{matrix}

where c was used to fit the singlet oxygen luminescence signal, and t R and t D are the rise and decay times [44–46]. Therefore, the Levenberg-Marquardt algorithm of Mathematica (Wolfram Research, Champaign, IL USA) was used.…”

Section: Materials and Methodologymentioning

confidence: 99%

Hydrogen Bond Acceptors and Additional Cationic Charges in Methylene Blue Derivatives: Photophysics and Antimicrobial Efficiency

Felgenträger

Maisch

Dobler

et al. 2013

BioMed Research International

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Photodynamic inactivation of bacteria (PIB) by efficient singlet oxygen photosensitizers might be a beneficial alternative to antibiotics in the struggle against multiresistant bacteria. Phenothiazinium dyes belong to the most prominent classes of such sensitizers due to their intense absorption in the red-light region (λ abs, max ca. 600–680 nm, ε > 50000 L mol−1 cm−1), their low toxicity, and their attachment/penetration abilities. Except simple substituents like alkyl or hydroxyalkyl residues, nearly no modifications of the phenothiaziniums have been pursued at the auxochromic sites. By this, the properties of methylene blue derivatives and their fields of application are limited; it remains unclear if their potential antimicrobial efficacy may be enhanced, also to compete with porphyrins. We prepared a set of six mainly novel methylene blue derivatives with the ability of additional hydrogen bonding and/or additional cationic charges to study the substituents' effect on their activity/toxicity profiles and photophysical properties. Direct detection of singlet oxygen was performed at 1270 nm and the singlet oxygen quantum yields were determined. In suspensions with both, Gram-positive and Gram-negative bacteria, some derivatives were highly active upon illumination to inactivate S. aureus and E. coli up to 7 log10 steps (99.99999%) without inherent toxicities in the nonirradiated state.

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\begin{matrix} I (t) = \frac{c}{t_{R}^{- 1} - t_{D}^{- 1}} [\exp (- \frac{t}{t_{D}}) - \exp (- \frac{t}{t_{R}})], \end{matrix}

Section: Materials and Methodologymentioning

confidence: 99%

Hydrogen Bond Acceptors and Additional Cationic Charges in Methylene Blue Derivatives: Photophysics and Antimicrobial Efficiency

Felgenträger

Maisch

Dobler

et al. 2013

BioMed Research International

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“…To determine the rise and decay times, the least-square fit routine of Mathematica (version 4.2; Wolfram Research, Berlin, Germany) was used, with an experimental error of Ϸ20%. Given the pair of time constants, D and R , it is sometimes difficult to decide which time is due to the deactivation of the triplet state T 1 and which is due to singlet oxygen luminescence (48). Additionally, the theory must be extended when bidirectional transfer takes place, as shown for Photofrin (15).…”

Section: Oxygen Concentration In Aqueous Bacterialmentioning

confidence: 99%

“…Thus, the decaying portion of luminescence should be attributed to the decay time of singlet oxygen (48).…”

Section: Singlet Oxygen Luminescence For Variable and High Bacterial mentioning

confidence: 99%

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The role of singlet oxygen and oxygen concentration in photodynamic inactivation of bacteria

Maisch¹,

Baier²,

Franz³

et al. 2007

Proc. Natl. Acad. Sci. U.S.A.

375

289

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New antibacterial strategies are required in view of the increasing resistance of bacteria to antibiotics. One promising technique involves the photodynamic inactivation of bacteria. Upon exposure to light, a photosensitizer in bacteria can generate singlet oxygen, which oxidizes proteins or lipids, leading to bacteria death. To elucidate the oxidative processes that occur during killing of bacteria, Staphylococcus aureus was incubated with a standard photosensitizer, and the generation and decay of singlet oxygen was detected directly by its luminescence at 1,270 nm. At low bacterial concentrations, the time-resolved luminescence of singlet oxygen showed a decay time of 6 ؎ 2 s, which is an intermediate time for singlet oxygen decay in phospholipids of membranes (14 ؎ 2 s) and in the surrounding water (3.5 ؎ 0.5 s). Obviously, at low bacterial concentrations, singlet oxygen had sufficient access to water outside of S. aureus by diffusion. Thus, singlet oxygen seems to be generated in the outer cell wall areas or in adjacent cytoplasmic membranes of S. aureus. In addition, the detection of singlet oxygen luminescence can be used as a sensor of intracellular oxygen concentration. When singlet oxygen luminescence was measured at higher bacterial concentrations, the decay time increased significantly, up to Ϸ40 s, because of oxygen depletion at these concentrations. This observation is an important indicator that oxygen supply is a crucial factor in the efficacy of photodynamic inactivation of bacteria, and will be of particular significance should this approach be used against multiresistant bacteria.luminescence ͉ oxygen depletion ͉ Staphylococcus aureus

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“…In controls, in which the rhodamine derivatives were not photoactivated, or the samples were irradiated in the absence of the 1 O 2 generators, no quenching of the detector molecules became apparent. To confirm the conclusion that TMRM is highly effective in generating 1 O 2 , the fluorescence quenching of 1,3-diphenylisobenzofuran and 9,10-diphenylanthracene was performed in the presence of D 2 O, which is known to increase the lifetime and thus the steady state level of 1 O 2 severalfold (30,31). In line with our view, the fluorescence quenching of the 1 O 2 detector molecules was enhanced 2-3-fold in the presence of D 2 O (data not shown).…”

Section: Oxidation Of Nad(p)h Bymentioning

confidence: 99%

NAD(P)H, a Primary Target of 1O2 in Mitochondria of Intact Cells

Petrat

Pindiur

Kirsch

et al. 2003

Journal of Biological Chemistry

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Direct reaction of NAD(P)H with oxidants like singlet oxygen ( 1 O 2 ) has not yet been demonstrated in biological systems. We therefore chose different rhodamine derivatives (tetramethylrhodamine methyl ester, TMRM; 2,4,5,7-tetrabromorhodamine 123 bromide; and rhodamine 123; Rho 123) to selectively generate singlet oxygen within the NAD(P)H-rich mitochondrial matrix of cultured hepatocytes. In a cell-free system, photoactivation of all of these dyes led to the formation of 1 O 2 , which readily oxidized NAD(P)H to NAD(P)؉ . In hepatocytes loaded with the various dyes only TMRM and Rho 123 proved suited to generating 1 O 2 within the mitochondrial matrix space. Photoactivation of the intracellular dyes (TMRM for 5-10 s, Rho 123 for 60 s) led to a significant (29.6 ؎ 8.2 and 30.2 ؎ 5.2%) and rapid decrease in mitochondrial NAD(P)H fluorescence followed by a slow reincrease. Prolonged photoactivation (>15 s) of TMRMloaded cells resulted in even stronger NAD(P)H oxidation, the rapid onset of mitochondrial permeability transition, and apoptotic cell death. These results demonstrate that NAD(P)H is the primary target for 1 O 2 in hepatocyte mitochondria. Thus NAD(P)H may operate directly as an intracellular antioxidant, as long as it is regenerated. At cell-injurious concentrations of the oxidant, however, NAD(P)H depletion may be the event that triggers cell death.Pyridine nucleotides, i.e. NAD(H) and NADP(H), play a central role in metabolism; they are the most important coenzymes acting as hydride (hydrogen anion) donors of various cellular dehydrogenases (e.g. glutathione reductase), functioning as reducing/oxidizing equivalents in essential reactions such as energy supply (aerobic or anaerobic) and photosynthesis, and are required for DNA repair.The ability of an organism to counteract reactive oxygen species (ROS) 1 or reactive nitrogen species depends on its antioxidative capabilities, which involves destroying of both prooxidants (e.g. ROOH, H 2 O 2 , ONOOH) and oxidants (e.g. radicals and reactive intermediates like singlet oxygen, 1 O 2 ). Whereas pro-oxidants are typically degraded by enzymes (e.g. catalase, glutathione peroxidase, and superoxide dismutase), oxidants are scavenged by relatively small biomolecules (e.g. ascorbic acid, glutathione, and ␣-tocopherol); these are termed directly operating antioxidants. In this context, NAD(P)H is crucial to maintaining the cellular redox state and/or antioxidative capacity, because of its essential role as a coenzyme in the enzymatic re-reduction of directly operating antioxidants (1, 2). Consequently, NAD(P)H deficiencies are linked with an increased sensitivity to oxidative stress (2, 3).The capability of NAD(P)H to additionally act as a directly operating antioxidant, i.e. to donate only one electron, was sharply underestimated by various biochemical researchers, a fact that is probably because of the observation that a biochemical standard one-electron oxidant, [Fe(CN) The H 2 O 2 -consuming enzymes catalase and glutathione peroxidase (GPx) strongly limi...

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Optical determination of the rates of formation and decay of O2(1Δg) in H2O, D2O and other solvents

Cited by 39 publications

References 5 publications

Hydrogen Bond Acceptors and Additional Cationic Charges in Methylene Blue Derivatives: Photophysics and Antimicrobial Efficiency

Hydrogen Bond Acceptors and Additional Cationic Charges in Methylene Blue Derivatives: Photophysics and Antimicrobial Efficiency

The role of singlet oxygen and oxygen concentration in photodynamic inactivation of bacteria

NAD(P)H, a Primary Target of 1O2 in Mitochondria of Intact Cells

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