&lt;title&gt;Photobleaching of photosensitizers applied for photodynamic therapy&lt;/title&gt;

Stratonnikov, Alexander A.; Meerovich, Gennadii A.; Loschenov, Victor B.

doi:10.1117/12.379885

Cited by 15 publications

(11 citation statements)

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“…The similar results have been observed also by other researchers [4,5]. Figure 5 demonstrates the blood oxygen saturation changes during PDT with suiphonated aluminum phthalocyanines as photosensitizer in mouse tumors [1,2]. We observe distinct vessel response to light irradiation in the presence of photosensitizer in blood.…”

Section: Resultssupporting

confidence: 91%

“…In other words whether vessel response to laser irradiation is related to low intensity therapy and photodynamic therapy (PDT). It was found out that control of vessel response by measuring blood oxygen saturation may be very useful in estimating and monitoring in real time the PDT effect to tissues [1,2]. Here we apply the same method of monitoring blood oxygen saturation in skin of healthy volunteers under influence of laser irradiation alone.…”

Section: Introductionmentioning

confidence: 91%

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Influence of red laser irradiation on hemoglobin oxygen saturation and blood volume in human skin in vivo

2001

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The aim of the present work was to study the response of hemoglobin oxygen saturation and relative blood volume in human skin in vivo to laser irradiation. The hemoglobin oxygen saturation and relative hemoglobin concentration in skin were evaluated from diffuse reflectance spectra in visible wavelength range. The skin spot at human hand was irradiated with laser beam and hemoglobin oxygen saturation and relative hemoglobin concentration were sampled every two second from the center of irradiated spot. It was evidently observed that hemoglobin oxygen saturation is increased after starting irradiation. During occlusion the oxygen consumption rate was higher in the presence of laser irradiation. However these effects were observed only at sufficiently high laser fluence rates. The most probable reason is that it is due to thermal effects.

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Section: Resultssupporting

confidence: 91%

Section: Introductionmentioning

confidence: 91%

Influence of red laser irradiation on hemoglobin oxygen saturation and blood volume in human skin in vivo

2001

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“…These species are unlikely to be singlet oxygen, which has a very short lifetime and thus radius of diffusion, but represent other radicals. 39 In this case, retinol may be regenerated by direct reduction or interaction with molecular oxygen. Ignoring triplet interactions, the possible reactions are where X are nonfluorescent products.…”

Section: Results and Discussionmentioning

confidence: 99%

Characterization of Retinol Stabilized in Phosphatidylcholine Vesicles with and without Antioxidants

Chmykh

Nadeau

2020

ACS Omega

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Retinol stability has been reported to be improved by encapsulation in liposomes, both with and without cholesterol. However, this improvement is limited because of lipid peroxidation. In this study, we compare the stability of retinol in phosphatidylcholine liposomes under ultraviolet (UV) light or standard room air, with and without the addition of antioxidants. Both butylated hydroxytoluene (BHT) and a proprietary mix (StoppOx) improved the shelf stability from <10 to over 30 d. The addition of cholesterol had no effect. Fluorescence imaging showed a heterogeneous distribution of retinol within the vesicles, including within the aqueous layer. Fluorescence lifetimes were equally heterogeneous. Under UV irradiation, StoppOx protected retinol for significantly longer than BHT and via different mechanisms. This suggests that natural antioxidants work well to improve the retinol stability, but that further work to determine the optimal vesicle structure remains to be performed.

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“…To analyze the time-lapse transient absorption signals, we utilized a mathematical model which was originally used to depict the photobleaching of photosensitizers happening during a photodynamic process 16 :…”

Section: Author Contributionsmentioning

confidence: 99%

“…We hypothesized that a specific chromophore in S. aureus is prone to photobleaching under the abovementioned setting. To verify the photobleaching phenomenon, we fitted the time-course curve with a photobleaching model 16 (Fig. 1b showed negligible effect on the bleaching speed (߬ ଶ = 0.14 ± 0.01 s, Supplementary Fig.…”

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confidence: 99%

Annihilation of Methicillin-resistant Staphylococcus aureus via Photobleaching of Staphyloxanthin

Dong

Mohammad

Wang

et al. 2017

Preprint

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Staphylococcus aureus causes a variety of diseases ranging from skin and soft tissue infections to life-threatening septicemia [6][7][8][9] . Moreover, S. aureus has acquired resistance to multiple antibiotic classes that were once effective 10 All rights reserved. No reuse allowed without permission.was not peer-reviewed) is the author/funder, who has granted bioRxiv a license to display the preprint in perpetuity.The copyright holder for this preprint (which . http://dx.doi.org/10.1101/227603 doi: bioRxiv preprint first posted online Dec. 1, 2017; 3Initially we attempted to differentiate MRSA from methicillin-susceptible S. aureus by transient absorption imaging (see Methods and Supplementary Fig. 1) of their intrinsic chromophores. Intriguingly, once the cultured S. aureus was placed under the microscope, the strong signal measured at zero delay between the 520-nm pump and 780-nm probe pulses quickly attenuated over second time scale (Fig. 1a and Supplementary Video 1). We hypothesized that a specific chromophore in S. aureus is prone to photobleaching under the abovementioned setting. To verify the photobleaching phenomenon, we fitted the time-course curve with a photobleaching model 16 ( Fig. 1b): showed negligible effect on the bleaching speed (߬ ଶ = 0.14 ± 0.01 s, Supplementary Fig. 3a). The same phenomenon was observed in methicillin-susceptible S. aureus ( Supplementary Fig. 3b).Collectively, these data support a second-order photobleaching process.Next, we aimed to deduce the specific chromophore inside S. aureus that accounts for the observed photobleaching phenomenon. It is known that carotenoids are photosensitive due to the All rights reserved. No reuse allowed without permission.was not peer-reviewed) is the author/funder, who has granted bioRxiv a license to display the preprint in perpetuity.The copyright holder for this preprint (which . http://dx.doi.org/10.1101/227603 doi: bioRxiv preprint first posted online Dec. 1, 2017; 4 conjugated C=C bonds 17,18 . Therefore, we hypothesized that staphyloxanthin (STX), a carotenoid pigment residing in the cell membrane of S. aureus, underwent photobleaching in our transient absorption study. To test this hypothesis, we treated MRSA with naftifine, a FDA-approved antifungal drug that blocks the synthesis of STX 3 . The treated MRSA exhibited lower signal intensity ( Fig. 1c) and slower photobleaching speed (Fig. 1d) 1f,h) only exhibited background induced by cross-phase modulation 20 , whereas the MRSA colony showed a sharp contrast against the background ( Fig. 1g) and a fast photobleaching decay ( Fig. 1h). Taken together, these data confirm that STX in S. aureus accounts for the observed photobleaching.In the transient absorption study, when changing 520-nm pump irradiance while fixing 780-nm probe intensity, both signal intensity and Fig. 4b,d). These findings collectively imply that photobleaching efficacy is highly dependent on the excitation wavelength ( Supplementary Fig. 4e), which is consistent with the fact that photobleaching is ground...

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<title>Photobleaching of photosensitizers applied for photodynamic therapy</title>

Cited by 15 publications

References 0 publications

Influence of red laser irradiation on hemoglobin oxygen saturation and blood volume in human skin in vivo

Influence of red laser irradiation on hemoglobin oxygen saturation and blood volume in human skin in vivo

Characterization of Retinol Stabilized in Phosphatidylcholine Vesicles with and without Antioxidants

Annihilation of Methicillin-resistant Staphylococcus aureus via Photobleaching of Staphyloxanthin

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