Time-resolved methods in biophysics. 7. Photon counting vs. analog time-resolved singlet oxygen phosphorescence detection

Jiménez-Banzo, Ana; Ragàs, Xavier; Kapusta, P.; Nonell, Santi

doi:10.1039/b804333g

Cited by 139 publications

(129 citation statements)

References 45 publications

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“…The fluorescence was excited at 375 nm by means of a pulsed laser diode working at 10 MHz repetition rate, and was observed at 420 nm keeping the counting frequency below 1%. Fluorescence decays were analysed using the PicoQuant FluoFit 4.5 data analysis software (PicoQuant, Germany) [26]. …”

Section: Methodsmentioning

confidence: 99%

On the mechanism of Candida tropicalis biofilm reduction by the combined action of naturally-occurring anthraquinones and blue light

et al. 2017

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The photoprocesses involved in the photo-induced Candida tropicalis biofilm reduction by two natural anthraquinones (AQs), rubiadin (1) and rubiadin-1-methyl ether (2), were examined. Production of singlet oxygen (1O2) and of superoxide radical anion (O2•−) was studied. Although it was not possible to detect the triplet state absorption of any AQs in biofilms, observation of 1O2 phosphorescence incubated with deuterated Phosphate Buffer Solution, indicated that this species is actually formed in biofilms. 2 was accumulated in the biofilm to a greater extent than 1 and produced measurable amounts of O2•− after 3h incubation in biofilms. The effect of reactive oxygen species scavengers on the photo-induced biofilm reduction showed that Tiron (a specific O2•− scavenger) is most effective than sodium azide (a specific 1O2 quencher). This suggests that O2•− formed by electron transfer quenching of the AQs excited states, is the main photosensitizing mechanism involved in the photo-induced antibiofilm activity, whereas 1O2 participation seems of lesser importance.

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Section: Methodsmentioning

confidence: 99%

On the mechanism of Candida tropicalis biofilm reduction by the combined action of naturally-occurring anthraquinones and blue light

et al. 2017

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“…Photon counting was achieved with a multichannel scaler (PicoQuant's Nanoharp 250). The fast ''spike'' in the earlier part of the signal, due to scattered laser light and sensitizer fluorescence [31] was eliminated by subtraction of a proper blank, that is, the signal at a wavelength where singlet oxygen does not emit (1140 nm). The corrected time-resolved emission signals were then analyzed using the FluoFit software to extract lifetime values by fitting [Eq.…”

Section: Methodsmentioning

confidence: 99%

Quantification of Photosensitized Singlet Oxygen Production by a Fluorescent Protein

et al. 2010

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Fluorescent proteins are increasingly becoming actuators in a range of cell biology techniques. One of those techniques is chromophore-assisted laser inactivation (CALI), which is employed to specifically inactivate the function of target proteins or organelles by producing photochemical damage. CALI is achieved by the irradiation of dyes that are able to produce reactive oxygen species (ROS). The combination of CALI and the labelling specificity that fluorescent proteins provide is useful to avoid uncontrolled photodamage, although the inactivation mechanisms by ROS are dependent on the fluorescent protein and are not fully understood. Herein, we present a quantitative study of the ability of the red fluorescent protein TagRFP to produce ROS, in particular singlet oxygen ((1)O(2)). TagRFP is able to photosensitize (1)O(2) with an estimated quantum yield of 0.004. This is the first estimation of a quantum yield of (1)O(2) production value for a GFP-like protein. We also find that TagRFP has a short triplet lifetime compared to EGFP, which reflects relatively high oxygen accessibility to the chromophore. The insight into the structural and photophysical properties of TagRFP has implications in improving fluorescent proteins for fluorescence microscopy and CALI.

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“…Production of the reactive species singlet oxygen was assessed by monitoring its specific phosphorescence at 1,275 nm with a setup described in detail elsewhere (Jiménez-Banzo et al, 2008). Hypericin was excited by a pulsed laser at 532 nm and the emission of singlet oxygen was detected by a dedicated near infrared photomultiplier.…”

Section: Singlet Oxygen Detectionmentioning

confidence: 99%

The complex of hypericin with β-lactoglobulin has antimicrobial activity with potential applications in dairy industry

Rodríguez-Amigo

Delcanale

Rotger

et al. 2015

Journal of Dairy Science

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Using a combination of molecular modeling and spectroscopic experiments, the naturally occurring, pharmacologically active hypericin compound is shown to form a stable complex with the dimeric form of β-lactoglobulin (β-LG). Binding is predicted to occur at the narrowest cleft found at the interface between monomers in the dimeric β-LG. The complex is able to preserve the fluorescence and singlet oxygen photosensitizing properties of the dye. The equilibrium constant for hypericin binding has been determined as Ka=1.40±0.07µM(-1), equivalent to a dissociation constant, Kd=0.71±0.03µM. The complex is active against Staphylococcus aureus bacteria. Overall, the results are encouraging for pursuing the potential application of the complex between hypericin and β-LG as a nanodevice with bactericidal properties for disinfection.

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Time-resolved methods in biophysics. 7. Photon counting vs. analog time-resolved singlet oxygen phosphorescence detection

Cited by 139 publications

References 45 publications

On the mechanism of Candida tropicalis biofilm reduction by the combined action of naturally-occurring anthraquinones and blue light

On the mechanism of Candida tropicalis biofilm reduction by the combined action of naturally-occurring anthraquinones and blue light

Quantification of Photosensitized Singlet Oxygen Production by a Fluorescent Protein

The complex of hypericin with β-lactoglobulin has antimicrobial activity with potential applications in dairy industry

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