Bidirectional energy transfer between the triplet T1 state of photofrin and singlet oxygen in deuterium oxide

Kilger, Robert; Maier, Max; Szeimies, Rolf‐Markus; Bäumler, Wolfgang

doi:10.1016/s0009-2614(01)00738-2

Cited by 18 publications

(17 citation statements)

References 16 publications

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“…This leads to prolonged phosphorescence and an increase in the decay time of the triplet state. In the absence of oxygen, the luminescence signal measured is equivalent to the triplet emission of Photofrin, which is Ϸ200 s (15). Thus, when we measure the time-resolved luminescence, the signal contains information about the oxygen concentration at the site of singlet oxygen generation, as either rise or decay time.…”

Section: Singlet Oxygen Luminescence For Variable and High Bacterial mentioning

confidence: 99%

“…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). There, the rise (␤ 1 ϭ 1/ R ) and decay (␤ 2 ϭ 1/ D ) rates are connected with two decay rates: K T , which is responsible for the relaxation of the T 1 state of the photosensitizer, and K ⌬ , which is responsible for the relaxation of the singlet oxygen state.…”

Section: Oxygen Concentration In Aqueous Bacterialmentioning

confidence: 99%

“…For low oxygen concentrations, the decay rate ␤ 2 can be equated with K T , which represents the decay rate of the photosensitizer triplet T 1 state. For high oxygen concentrations, decay rate ␤ 2 can be equated with the relaxation rate of singlet oxygen, K ⌬ (15,48).…”

Section: Oxygen Concentration In Aqueous Bacterialmentioning

confidence: 99%

“…Either charge (type I reaction) or energy (type II reaction) is transferred to a substrate or to molecular oxygen to generate reactive oxygen species (13). In photodynamic action, singlet oxygen ( 1 O 2 ) is considered to play the major role (14,15). This highly reactive oxygen initiates further oxidative reactions in the proximate environment, such as the bacterial cell wall, lipid membranes, enzymes, or nucleic acids (16,17).…”

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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.

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384

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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Section: Singlet Oxygen Luminescence For Variable and High Bacterial mentioning

confidence: 99%

Section: Oxygen Concentration In Aqueous Bacterialmentioning

confidence: 99%

Section: Oxygen Concentration In Aqueous Bacterialmentioning

confidence: 99%

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.

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384

289

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“…In a type II reaction the excited photosensitizer reacts directly with molecular oxygen. Therefore, the excited photosensitizer may then react with normal triplet oxygen to produce singlet oxygen ( 1 O 2 ) when the photosensitizer returns to its ground state, the singlet state (31,33). This highly reactive singlet oxygen initiates further oxidative reactions in a closed environment, like the bacterial cell wall, lipid membranes, enzymes, or nucleic acids (6,28).…”

mentioning

confidence: 99%

Photodynamic Effects of Novel XF Porphyrin Derivatives on Prokaryotic and Eukaryotic Cells

Maisch¹,

Bosl²,

Szeimies³

et al. 2005

Antimicrob Agents Chemother

212

138

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The worldwide rise in the rates of antibiotic resistance of bacteria underlines the need for alternative antibacterial agents. A promising approach to the killing of gram-positive antibiotic-resistant bacteria of the skin uses light in combination with a photosensitizer to induce a phototoxic reaction. Different concentrations (0 to 100 M) of porphyrin-based photosensitizers (CTP1, XF70, and XF73) and different incubation times (5 min, 1 h, and 4 h) were used to determine phototoxicity against two methicillin-resistant Staphylococcus aureus strains, one methicillin-sensitive S. aureus strain, one methicillin-resistant Staphylococcus epidermidis strain, one Escherichia coli strain, and human keratinocytes and fibroblasts. Incubation with 0.005 M XF70 or XF73, followed by illumination, yielded a 3-log 10 (>99.9%) decrease in the viable cell numbers of all staphylococcal strains, indicating that the XF drugs have high degrees of potency against gram-positive bacteria and also that the activities of these novel drugs are independent of the antibiotic resistance pattern of the staphylococci examined. CTP1 was less potent against the staphylococci under the same conditions. At 0.005 M, XF70 and XF73 demonstrated no toxicity toward fibroblasts or keratinocytes. No inactivation of E. coli was detected at this concentration. XF73 was confirmed to act via a reactive oxygen species from the results of studies with sodium azide (a quencher of singlet oxygen), which reduced the killing of both eukaryotic and prokaryotic cells. When a quencher of superoxide anion and the hydroxyl radical was used, cell killing was not inhibited. These results demonstrate that the porphyrin-based photosensitizers had concentration-dependent differences in their efficacies of killing of methicillin-resistant staphylococcal strains via reactive oxygen species without harming eukaryotic cells at the same concentrations.

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Structure-activity relationships of three differently substituted 2,7,12,17-tetrakis-(�-methoxyethyl) porphycene derivatives in vitro

Scherer

Abels

Bäumler

et al. 2004

Archives of Dermatological Research

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The subcellular localization, efficacy and photooxidative mechanism of three new photosensitizing porphycenes (HexoTMPn, PeloTMPn, CpoTMPn) for photodynamic therapy with different substituents at position 9 of the tetrapyrrole macrocycle were investigated in vitro using different human skin-derived cell lines (HaCaT, SCL I, SCL II) with the aim of customizing the side-chain chemistry to accelerate cellular uptake and so enhance photodynamic activity. Cells were incubated with a porphycene and costained with organelle-specific markers. Subcellular localization was determined by fluorescence microscopy. Also, cells were incubated with different sensitizer concentrations (0-1000 nmol/l) and irradiated by an incoherent light source (lambda(em) = 600-750 nm, 40 mW/cm(2), 24 J/cm(2)) with/without quenchers or enhancers (NaN(3), histidine, mannitol or D(2)O). Cell viability was assessed. All porphycenes were localized in perinuclear lysosomes and induced a decrease in mitochondrial activity following irradiation. HexoTMPn was the most efficient in all three cell lines (EC(50) in HaCaT cells: HexoTMPn 14 nmol/l, CpoTMPn 62 nmol/l, PeloTMPn 89 nmol/l). Addition of either NaN(3) or histidine reduced the phototoxicity significantly. Due to the short lifetime of singlet oxygen, the sites of sensitizer localization are the initial subcellular targets. The cytotoxicity of each sensitizer varied depending on singlet oxygen quantum yield and cell line. Despite the different chemical structures, the biological effects were not very distinct, since they seemed to be mostly determined by the tetrapyrrole ring and only slightly modified by the substituent at position 9. Also, there was only a narrow margin between biological compatibility and efficacy.

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Bidirectional energy transfer between the triplet T1 state of photofrin and singlet oxygen in deuterium oxide

Cited by 18 publications

References 16 publications

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

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

Photodynamic Effects of Novel XF Porphyrin Derivatives on Prokaryotic and Eukaryotic Cells

Structure-activity relationships of three differently substituted 2,7,12,17-tetrakis-(�-methoxyethyl) porphycene derivatives in vitro

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