Photosensitized Lysis of Liposomes by Hematoporphyrin Derivative

Grossweiner, Leonard I.; Goyal, Greesh C.

doi:10.1111/j.1751-1097.1983.tb04513.x

Cited by 42 publications

(13 citation statements)

References 9 publications

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“…Lysis of liposomes that was observed in the group of Grossweiner (45–47) was achieved with light intensities that were higher than in normal PDT. Thus, liposomal membrane diffusion potential is not abolished as a consequence of photosensitization, under conditions that lead to massive death of animal and bacterial cells.…”

Section: Discussionmentioning

confidence: 91%

Lipid Composition Affects the Rate of Photosensitized Dissipation of Cross-Membrane Diffusion Potential on Liposomes

et al. 2010

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Hydrophobic or amphiphilic tetrapyrrole sensitizers are taken up by cells and are usually located in cellular lipid membranes. Singlet oxygen is photogenerated by the sensitizer and it diffuses in the membrane and causes oxidative damage to membrane components. This damage can occur to membrane lipids and to membrane-localized proteins. Depolarization of the Nernst electric potential on cells' membranes has been observed in cellular photosensitization, but it was not established whether lipid oxidation is a relevant factor leading to abolishing the resting potential of cells' membranes and to their death. In this work we studied the effect of liposomes' lipid composition on the kinetics of hematoporphyrin-photosensitized dissipation of K + -diffusion electric potential that was generated across the membranes. We employed an electrochromic voltage-sensitive spectroscopic probe that possesses a high fluorescence signal response to the potential. We found a correlation between the structure and unsaturation of lipids and the leakage of the membrane, following photosensitization. As the extent of non-conjugated unsaturation of the lipids is increased from 1 to 6 double bonds, the kinetics of depolarization become faster. We also found that the kinetics of depolarization is affected by the percentage of the unsaturated lipids in the liposome: as the fraction of the unsaturated lipids increases the leakage trough the membrane is enhanced. When liposomes are composed of a lipid mixture similar to that of natural membranes and photosensitization is being carried out under usual photodynamic therapy (PDT) conditions, photodamage to the lipids is not likely to cause enhanced permeability of ions through the membrane, which would have been a mechanism that leads to cell death.

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Section: Discussionmentioning

confidence: 91%

Lipid Composition Affects the Rate of Photosensitized Dissipation of Cross-Membrane Diffusion Potential on Liposomes

et al. 2010

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“…Liposome bilayers of lipids are similar in structure to living cell membranes (9–11). They have been used to study the peroxidation of lipid membranes (12–15), enzyme activities in membranes (16) or phototoxicity mechanisms (17). In the present work, liposomes were used as a membrane model to study the efficiency of UV filters in vitro.…”

Section: Introductionmentioning

confidence: 99%

A New Model Using Liposomes That Allow to Distinguish Between Absorption and Oxidative Properties of Sunscreens¶

Tran¹,

Sorg²,

Carraux³

et al. 2002

Photochemistry and Photobiology

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We have developed a new model using liposome-encapsulated fluorescent probes, aiming at assessing both the physical and the biological protection provided by filter molecules such as those incorporated in sunscreens. The fluorescent indicator Indo-1 or 2',7'-dichlorofluorescin (DCFH) was inside the liposomes, in the aqueous inner compartment, whereas the filter molecules octyl methoxycinnamate (OMC), benzophenone-3 (BP3) or avobenzone, widely used in sunscreens, were incorporated into liposome membranes. When liposome suspensions were placed in a fluorometer cuvette exposed to an incident UV beam, the decrease of Indo-1 fluorescence as a function of filter concentration was related to the extinction coefficient of the filters. On the other hand, when liposome suspensions were exposed to moderate UVB doses allowing Indo-1 photobleaching, the remaining intact Indo-1 was linked to the protection provided by filter-containing liposome membranes. Finally, when liposome-encapsulated DCFH was exposed to UVB, the degree of photo-oxidation of the fluorescent probe into 2',7'-dichlorofluorescein accounted for the photoprotection provided by the filter contained in liposome membranes. BP3 was more potent and slightly less efficient than the other two filters in preventing Indo-1 fluorescence; all three filters provided a similar concentration-dependent protection of Indo-1 photobleaching, whereas only OMC was able to prevent the photooxidation of DCFH. The liposome model presented here has the advantage of combining both physical and biological parameters to assess the photoprotection provided by filter molecules, and the lack of photoprotection by two sunscreen molecules having a good filter capacity highlights the need for such a biological parameter when talking about the safety of sunscreens.

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“…(1978). The HpD-A fraction was separated by fractionation on Bio-Gel P-10 (Bio-Rad Laboratories) following the procedure of Grossweiner and Goyal (1983). The liposomes were prepared with egg yolk L-a-phosphatidylcholine (Sigma type VII E) by swelling the dry lipid film in buffer followed by probe sonication under N2 for 2 h (Goyal er a/.. 1983).…”

Section: Introductionmentioning

confidence: 99%

SINGLET OXYGEN GENERATION BY HEMATOPORPHYRIN IX, UROPORPHYRIN I and HEMATOPORPHYRIN DERIVATIVE AT 546 nm IN PHOSPHATE BUFFER and IN THE PRESENCE OF EGG PHOSPHATIDYLCHOLINE LIPOSOMES

Blum

Grossweiner

1985

Photochem & Photobiology

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122

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Abstract— The quantum yield of singlet oxygen generation (φ) was measured at 546 nm with the p‐nitrosodimethylaniline (RNO) method. The results obtained in pH 7.4 phosphate buffer (PB) were: φ(HP) = 0.44 ± 0.05: φ= 0.71 ± 0.07: φ(HpD‐A) = 0.06 ± 0.02. The value of φ was constant from 3 to 67 μM, attributed to the dominance of HP dimers; φ (HP) increased to 0.77 ± 0.13 in the presence of small egg phosphatidylcholine liposomes (SUV), attributed to solubilization and monomerization: φ (HpD‐A) increased to 0.87 ± 0.17 in the presence of SUV. attributed to monomerization of the impurity porphyrins and unfolding of the covalent dimer constituents. The quantum efficiency of the RNO system (100 μM RNO plus 10 mM histidine) was approximately 0.015 at pH 7.4 and increased significantly at lower pH.

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Photosensitized Lysis of Liposomes by Hematoporphyrin Derivative

Cited by 42 publications

References 9 publications

Lipid Composition Affects the Rate of Photosensitized Dissipation of Cross-Membrane Diffusion Potential on Liposomes

Lipid Composition Affects the Rate of Photosensitized Dissipation of Cross-Membrane Diffusion Potential on Liposomes

A New Model Using Liposomes That Allow to Distinguish Between Absorption and Oxidative Properties of Sunscreens¶

SINGLET OXYGEN GENERATION BY HEMATOPORPHYRIN IX, UROPORPHYRIN I and HEMATOPORPHYRIN DERIVATIVE AT 546 nm IN PHOSPHATE BUFFER and IN THE PRESENCE OF EGG PHOSPHATIDYLCHOLINE LIPOSOMES

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