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Soares ARM, Taniguchi M, Chandrashaker V, Lindsey JS. Self-organization of tetrapyrrole constituents to give a photoactive protocell. Chem Sci 2012. [DOI: 10.1039/c2sc01120d] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
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Ibrahim H, Kasselouri A, You C, Maillard P, Rosilio V, Pansu R, Prognon P. Meso-tetraphenyl porphyrin derivatives: The effect of structural modifications on binding to DMPC liposomes and albumin. J Photochem Photobiol A Chem 2011. [DOI: 10.1016/j.jphotochem.2010.09.008] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
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Vermathen M, Vermathen P, Simonis U, Bigler P. Time-dependent interactions of the two porphyrinic compounds chlorin e6 and mono-L-aspartyl-chlorin e6 with phospholipid vesicles probed by NMR spectroscopy. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2008; 24:12521-12533. [PMID: 18823137 DOI: 10.1021/la802040v] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/26/2023]
Abstract
The distribution processes of chlorin e6 (CE) and monoaspartyl-chlorin e6 (MACE) between the outer and inner phospholipid monolayers of 1,2-dioleoyl-phosphatidylcholine (DOPC) vesicles were monitored by 1H NMR spectroscopy through analysis of chemical shifts and line widths of the DOPC vesicle resonances. Chlorin adsorption to the outer vesicle monolayer induced changes in the DOPC 1H NMR spectrum. Most pronounced was a split of the N-methyl choline resonance, allowing for separate analysis of inner and outer vesicle layers. Transbilayer distribution of the chlorin compounds was indicated by time-dependent characteristic spectral changes of the DOPC resonances. Kinetic parameters for the flip-flop processes, that is, half-lives and rate constants, were obtained from the experimental data points. In comparison to CE, MACE transbilayer movement was significantly reduced, with MACE remaining more or less attached to the outer membrane layer. The distribution coefficients for CE and MACE between the vesicular and aqueous phase were determined. Both CE and MACE exhibited a high affinity for the vesicular phase. For CE, a positive correlation was found between transfer rate and increasing molar ratio CE/DOPC. Enhanced membrane rigidity induced by increasing amounts of cholesterol into the model membrane was accompanied by a decrease of CE flip-flop rates across the membrane. The present study shows that the movement of porphyrins across membranes can efficiently be investigated by 1H NMR spectroscopy and that small changes in porphyrin structure can have large effects on membrane kinetics.
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Affiliation(s)
- Martina Vermathen
- Department of Chemistry and Biochemistry, University of Bern, Freiestrasse 3, CH-3012 Bern, Switzerland.
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Bonneau S, Vever-Bizet C. Tetrapyrrole photosensitisers, determinants of subcellular localisation and mechanisms of photodynamic processes in therapeutic approaches. Expert Opin Ther Pat 2008. [DOI: 10.1517/13543776.18.9.1011] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
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Bonneau S, Vever-Bizet C, Mojzisova H, Brault D. Tetrapyrrole-photosensitizers vectorization and plasma LDL: A physico-chemical approach. Int J Pharm 2007; 344:78-87. [PMID: 17656052 DOI: 10.1016/j.ijpharm.2007.06.019] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/06/2007] [Revised: 06/01/2007] [Accepted: 06/06/2007] [Indexed: 11/16/2022]
Abstract
A photosensitizer is defined as a chemical entity able to induce, under light-irradiation effect, a chemical or physical alteration of another chemical entity. Thanks to their preferential retention in proliferating tissues, some photosensitizers are therapeutically used such as in photodynamic therapy (PDT). Besides, this method has already been approved for several indications. The selectivity of photosenzitizers for cells in proliferation involves both their association with low density lipoproteins (LDLs) and their ability to cross membranes under various pH conditions. The photosensitizers used are in most cases based on the porphyrin structure, but other compounds, of which far-red-light absorption properties are most compatible with biological tissues irradiation, have been developed, such as phthalocyanines. This paper presents physico-chemical studies of the interaction of a disulfonated aluminium phthalocyanine (AlPcS2) with human LDLs. The data obtained are compared with the parameters of the interaction of these lipoproteins with deuteroporphyrin (DP) and chlorin e6 (Ce6). A close attention is paid to the dynamic aspects of these phenomena. The data obtained on these simple systems then allowed us to interpret the sub-cellular localization of the photosensitizers on a human line of fibroblasts, and to evaluate the influence of LDLs on the intracellular distribution of the compounds. This last point is of major importance because the localization of such photosensitizers (in particular AlPcS2) in endocytic vesicles and their subsequent ability to induce a release of the contents of these vesicles - including externally added macromolecules - into the cytosol is the basis for a recent method for macromolecule activation, named photochemical internalization (PCI). PCI has been shown to potentiate the biological activity of a large variety of macromolecules. The comprehension of the mechanisms governing this particular sub-cellular localization could allow the design of better candidates for PCI.
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Affiliation(s)
- Stéphanie Bonneau
- Université Pierre et Marie Curie, Paris 6, UMR 7033, BioMoCeTi, Paris, F-75005, France.
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Mojzisova H, Bonneau S, Brault D. Structural and physico-chemical determinants of the interactions of macrocyclic photosensitizers with cells. EUROPEAN BIOPHYSICS JOURNAL: EBJ 2007; 36:943-53. [PMID: 17628795 DOI: 10.1007/s00249-007-0204-9] [Citation(s) in RCA: 50] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/15/2007] [Revised: 05/28/2007] [Accepted: 06/12/2007] [Indexed: 12/14/2022]
Abstract
New therapies have been developed using reactive oxygen species produced by light-activation of photosensitizers (PS). Since the lifetime of these species is extremely short and their diffusion in space is limited, the photo-induced reactions primarily affect the cell organelles labeled by the PS. In addition to the development of molecules with the best optical and photosensitizing properties, considerable research has been done to understand the physico-chemical parameters governing their subcellular localization. In this review, we examine these parameters to establish the structure/efficacy relationships, which allow specific targeting of PS. We examine the effect of subcellular localization on the cellular response to photosensitization processes. We discuss the determinants of subcellular localization, including the hydrophobic/hydrophilic balance, the specific charge effects and the dynamics of PS' transfer through membranes. Specific targeting can also be achieved with molecular structures able to recognize cellular or intracellular receptors, and this is also dealt with in this paper.
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Affiliation(s)
- Halina Mojzisova
- Laboratoire de Biophysique Moléculaire Cellulaire et Tissulaire (BIOMOCETI), CNRS UMR 7033, Université Pierre and Marie Curie, Genopole Campus 1, 5 rue Henri Desbruères, 91030, Evry Cedex, Paris, France.
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Bonneau S, Morlière P, Brault D. Dynamics of interactions of photosensitizers with lipoproteins and membrane-models: correlation with cellular incorporation and subcellular distribution. Biochem Pharmacol 2004; 68:1443-52. [PMID: 15345334 DOI: 10.1016/j.bcp.2004.06.014] [Citation(s) in RCA: 37] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2004] [Accepted: 06/17/2004] [Indexed: 10/26/2022]
Abstract
The incorporation and subcellular localization of photosensitizers are critical determinants of their efficiency. Here, we correlate these properties with the interactions of photosensitizers with membrane-models and low density lipoproteins (LDL) in acellular systems. Focus was given on dynamics aspects. Two amphiphilic photosensitizers, deuteroporphyrin (DP) and aluminum phthalocyanine sulfonated on two adjacent isoindole units (AlPcS2a) were selected. The phthalocyanine was bound to LDL with an overall association constant around 5 x 10(7)M(-1). Biphasic association kinetics was indicative of two types of sites. The release of the phthalocyanine into the bulk aqueous medium occurred within less than a second. A similar behavior was found previously for deuteroporphyrin although its affinity was somewhat higher (5.5 x 10(8)M(-1)). Both compounds were previously characterized by high affinity for membrane-models and quick exchange with the bulk solution. However, they strongly differed by their rate of transfer through the lipid bilayer, in the range of seconds for the porphyrin, several hours for the phthalocyanine. In the case of the porphyrin, fluorescence microscopy on human fibroblasts showed diffuse labeling with no significant modification of the distribution upon vectorization by LDL. In contrast, the phthalocyanine was localized in intracellular vesicles. Vectorization by LDL favored lysosomal localization although little effect was found on the overall uptake as shown by extraction experiments. The role of lipoproteins in the cellular localization of photosensitizers is significantly more important for photosensitizers not freely diffusing through bilayers. The dynamics of the interactions of photosensitizers with membranes appears as an important determinant of their subcellular localization.
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Affiliation(s)
- Stéphanie Bonneau
- Laboratoire de Physicochimie Biomoléculaire et Cellulaire, Université Pierre et Marie Curie, CNRS UMR 7033, 75005 Paris, France
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Bonneau S, Maman N, Brault D. Dynamics of pH-dependent self-association and membrane binding of a dicarboxylic porphyrin: a study with small unilamellar vesicles. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2004; 1661:87-96. [PMID: 14967478 DOI: 10.1016/j.bbamem.2003.12.002] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/01/2003] [Revised: 12/03/2003] [Accepted: 12/03/2003] [Indexed: 11/23/2022]
Abstract
Steady-state and stopped-flow measurements of the absorbance and fluorescence of aqueous solutions were performed to characterize the pH-dependent ionization and aggregation states of deuteroporphyrin. Porphyrin self-association promoted by neutralization of the carboxylic groups takes place within a few milliseconds impeding characterization of the monomer ionization states. Extrapolation at infinite dilution of the values obtained from steady-state measurements yielded the pKs of the carboxylic groups (6.6, 5.3) and inner nitrogens (4.1, 2.3). The kinetics of interactions of the porphyrin with unilamellar fluid state dioleoylphosphatidylcholine vesicles was examined in a large pH range, with focus on the entry step. From alkaline pH to a value of 6.5, the entrance rate is maximal (1.69 x 10(6) M(-1) s(-1) versus phospholipid concentration). It decreases to 2.07 x 10(5) M(-1) s(-1) at lower pH with an apparent pK of 5.39. This effect appears to be related to the formation of porphyrin dimer rather than to the protonation of inner nitrogen. In keeping with previous data, these results support the concept of a pH-mediated selectivity of carboxylic porphyrins for tumor. They also indicate that the propensity of these molecules to self-associate at low pH could yield to some retention in acidic intracellular vesicles of the endosome/lysosome compartment.
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Affiliation(s)
- Stéphanie Bonneau
- Laboratoire de Physicochimie Biomoléculaire et Cellulaire, CNRS UMR 7033, Université Pierre et Marie Curie, 75005 Paris, France
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Bonneau S, Vever-Bizet C, Morlière P, Mazière JC, Brault D. Equilibrium and kinetic studies of the interactions of a porphyrin with low-density lipoproteins. Biophys J 2002; 83:3470-81. [PMID: 12496113 PMCID: PMC1302421 DOI: 10.1016/s0006-3495(02)75346-0] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
Abstract
Low-density lipoproteins (LDL) play a key role in the delivery of photosensitizers to tumor cells in photodynamic therapy. The interaction of deuteroporphyrin, an amphiphilic porphyrin, with LDL is examined at equilibrium and the kinetics of association/dissociation are determined by stopped-flow. Changes in apoprotein and porphyrin fluorescence suggest two classes of bound porphyrins. The first class, characterized by tryptophan fluorescence quenching, involves four well-defined sites. The affinity constant per site is 8.75 x 10(7) M(-1) (cumulative affinity 3.5 x 10(8) M(-1)). The second class corresponds to the incorporation of up to 50 molecules into the outer lipidic layer of LDL with an affinity constant of 2 x 10(8) M(-1). Stopped-flow experiments involving direct LDL porphyrin mixing or porphyrin transfer from preloaded LDL to albumin provide kinetic characterization of the two classes. The rate constants for dissociation of the first and second classes are 5.8 and 15 s(-1); the association rate constants are 5 x 10(8) M(-1) s(-1) per site and 3 x 10(9) M(-1) s(-1), respectively. Both fluorescence and kinetic analysis indicate that the first class involves regions at the boundary between lipids and the apoprotein. The kinetics of porphyrin-LDL interactions indicates that changes in the distribution of photosensitizers among various carriers could be very sensitive to the specific tumor microenvironment.
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Affiliation(s)
- Stéphanie Bonneau
- Laboratoire de Photobiologie, Muséum National d'Histoire Naturelle, 43 rue Cuvier, 75231 Paris Cedex 05, France
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Galántai R, Bárdos-Nagy I, Módos K, Kardos J, Závodszky P, Fidy J. Serum albumin-lipid membrane interaction influencing the uptake of porphyrins. Arch Biochem Biophys 2000; 373:261-70. [PMID: 10620347 DOI: 10.1006/abbi.1999.1522] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
It is frequently observed in pharmaceutical practice that entrapped substances are lost rapidly when liposomes are used as carriers to introduce substances into cells. The reason for the loss is the interaction of serum components with liposomes. To elucidate the mechanism of this phenomenon the partition of mesoporphyrin (MP) was systematically studied in model systems composed of various lipids and human serum albumin (HSA). As surface charge is an important factor in the interaction, neutral (1, 2-dimyristoyl-sn-glycero-3-phosphatidylcoline, DMPC) and negatively charged (1,2-dimyristoyl-sn-glycero-3-phosphatidylcoline/1, 2-dimyristoyl-sn-glycero-3-phosphatidylglycerol, DMPC/DMPG = 19/1 w/w) lipids were compared. The liposome/apomyoglobin system was the negative control. The size distribution of sonicated samples was carefully analyzed by dynamic light scattering. Constants of association of MP to the proteins and to the liposomes were determined: K(p,1) = (2.5 +/- 0.7) x 10(7) M(-1), K(p,2) = (1.0 +/- 0.7) x 10(8) M(-1), K(L,1) = (1.3 +/- 0.3) x 10(5) M(-1), and K(L,2) = (3.2 +/- 0.6) x 10(4) M(-1) for HSA, apomyoglobin, DMPC, and DMPC/DMPG liposomes, respectively. These data were used to evaluate the partition experiments. The transfer of MP from the liposomes to the proteins was followed by fluorescence spectroscopy. In the case of apomyoglobin, the experimental points could be interpreted by ruling out the protein-liposome interaction. In the case of HSA, the efflux of MP from the liposomes was strongly inhibited above a critical HSA concentration range for negatively charged vesicles. This effect was interpreted as the result of HSA coat formation on the liposome surface. This direct interaction is significant for small liposomes. The interpretation is fully supported by differential scanning calorimetry experiments.
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Affiliation(s)
- R Galántai
- Institute of Biophysics and Radiation Biology, Semmelweis University of Medicine, Budapest, H-1444, Hungary
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Maman N, Dhami S, Phillips D, Brault D. Kinetic and equilibrium studies of incorporation of di-sulfonated aluminum phthalocyanine into unilamellar vesicles. BIOCHIMICA ET BIOPHYSICA ACTA 1999; 1420:168-78. [PMID: 10446300 DOI: 10.1016/s0005-2736(99)00093-0] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
The interactions of cis-di-sulfonated aluminum phthalocyanine (PcS(2)Al) with dimyristoylphosphatidylcholine (DMPC) unilamellar vesicles have been investigated by fluorescence spectroscopy. At pH 7.0, PcS(2)Al incorporates into the vesicles with a high affinity constant (2.7x10(6) M(-1), in terms of phospholipid concentration). The fluorescence changes following rapid mixing of PcS(2)Al with vesicles are biphasic. The first phase is attributed to the entry of PcS(2)Al into the vesicles, as deduced from the linear dependence of the rate upon lipid concentration. More surprisingly, this rate is strongly pH dependent with a marked maximum around pH 7.3, a result interpreted in terms of the coordination state of the aluminum ion in aqueous solutions. At this pH, a hydroxide ion neutralizes the residual positive charge of the metal ion that remains unbalanced after coordination by the phthalocyanine cycle. A water molecule is likely to complete the metal coordination sphere. Only this form, PcAl(+)(OH(-))(OH(2)), with an uncharged core is quickly incorporated into the vesicles. The protonation of OH(-) or the deprotonation of the coordinated H(2)O leading to a positively or negatively charged core, respectively, account for the observed pH effect. Studies on the effect of cholesterol addition and exchange of PcS(2)Al between vesicles and albumin all indicate the absence of transfer of the phthalocyanine between the vesicle hemileaflets, a result expected from the presence of the two negatively charged sulfonated groups at the ring periphery. Instead, the slower kinetic phase is likely due to the movement of the phthalocyanine becoming more buried within the outer leaflet upon the loss of the water molecule coordinated to the aluminum ion.
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Affiliation(s)
- N Maman
- Laboratoires de Photobiologie et de Biophysique, CNRS UMR 8646, INSERM U. 201, Muséum National d'Histoire Naturelle, 43 rue Cuvier, 75005, Paris, France
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Bárdos-Nagy I, Galántai R, Kaposi AD, Fidy J. Difference in the transport of metal and free-base porphyrins steady-state and time-resolved fluorescence studies. Int J Pharm 1998. [DOI: 10.1016/s0378-5173(98)00294-4] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
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Maman N, Brault D. Kinetics of the interactions of a dicarboxylic porphyrin with unilamellar lipidic vesicles: interplay between bilayer thickness and pH in rate control. BIOCHIMICA ET BIOPHYSICA ACTA 1998; 1414:31-42. [PMID: 9804879 DOI: 10.1016/s0005-2736(98)00149-7] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
The transfer of a dicarboxylic porphyrin from phosphatidylcholine fluid-phase unilamellar vesicles towards albumin is studied focusing on bilayer thickness and pH effects. The kinetics of this process yield the rate constants for the porphyrin flip-flop from the inner to the outer hemileaflet and its exit towards aqueous medium. Phospholipids with monounsaturated 14-22 carbon chains are used. Interplay between bilayer thickness and pH for the control of the rate constants is observed. This results in the amplification, at physiological pH, of the effect of membrane thickness on the flip-flop and exit rates as compared to pH 8.5 and 6.5. These data are explained by the degree of porphyrin burying within the bilayer resulting from a compromise between favorable hydrophobic interactions with the hydrocarbon phase and unfavorable penetration of the polar carboxylic chains. The balance between the two effects depends particularly on the neutralization of one carboxylic chain. Considering the bilayer hydrophobicity profile and the porphyrin size, the optimization of hydrophobic interactions appears dependent on the bilayer thickness. The flip-flop and the exit are governed by neutralization and deprotonation of the carboxylic chains, respectively, the rate of these proton exchanges being dependent on the porphyrin location within the bilayer.
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Affiliation(s)
- N Maman
- Laboratoires de Photobiologie et de Biophysique, CNRS UA 481, INSERM U. 201, Muséum National d'Histoire Naturelle, 43 rue Cuvier, 75231 Paris Cedex 05, France
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Berki T, Németh P. Novel method for in vitro depletion of T cells by monoclonal antibody-targeted photosensitization. J Immunol Methods 1998; 211:139-46. [PMID: 9617838 DOI: 10.1016/s0022-1759(97)00201-9] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
An immunotargeting method (called photo-immunotargeting) has been developed for selective in vitro cell destruction. The procedure combines the photosensitizing (toxic) effect of light-induced dye-molecules, e.g., hematoporphyrin (HP) and the selective binding ability of monoclonal antibodies (mAb) to cell surface molecules. The photosensitizer HP molecules were covalently attached to monoclonal antibodies (a-Thy-1) recognizing an antigen on the surface of T lymphocytes, and used for T cell destruction. To increase the selectivity of the conventional targeting methods, a physical activation step (local light irradiation) as a second degree of specificity was employed. The HP in conjugated form was sufficient to induce T cell (thymocytes, EL-4 cell line) death after irradiation at 400 nm, at tenfold lower concentration compared to the photosensitizing effect of unbound HP. The selective killing of T lymphocytes (bearing the Thy-1 antigen) in a mixed cell population was demonstrated after a treatment with the phototoxic conjugate and light irradiation. This method can be useful for selective destruction of one population (target cell) in an in vitro heterogeneous cell mixture, e.g., in bone marrow transplants for T cell depletion to avoid graft vs. host reaction.
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Affiliation(s)
- T Berki
- Department of Immunology and Biotechnology, University Medical School of Pécs, Hungary.
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Lundahl P, Beigi F. Immobilized liposome chromatography of drugs for model analysis of drug-membrane interactions. Adv Drug Deliv Rev 1997. [DOI: 10.1016/s0169-409x(96)00437-1] [Citation(s) in RCA: 60] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/17/2022]
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Kuzelová K, Brault D. Interactions of dicarboxylic porphyrins with unilamellar lipidic vesicles: drastic effects of pH and cholesterol on kinetics. Biochemistry 1995; 34:11245-55. [PMID: 7669783 DOI: 10.1021/bi00035a034] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
Abstract
The effect of pH on the transfer of deuteroporphyrin from dimyristoylphosphatidylcholine (DMPC) unilamellar vesicles to human serum albumin is investigated using a stopped-flow with fluorescence detection. The kinetics of this process allows for the determination of the rate constants for the porphyrin exist from the outer vesicle layer to the bulk aqueous medium (koff), and for its movement from the inner to the outer vesicle layer (kto). Both koff and kto are found to strongly depend on the pH. The observed behavior can be described by classical titration curves and is most likely due to protonation equilibria involving the two carboxylic groups of the porphyrin. A pH increase accelerates the exist of the porphyrin. The reverse effect is observed for its movement through the bilayer. The presence of cholesterol in the DMPC bilayer also strongly affects the interactions of the porphyrin with the vesicles. The rate constant kto is dramatically reduced by increasing the cholesterol content. An irregularity is noted around 10-20 mol % cholesterol. The results are discussed in relation to the preferential uptake of porphyrins by tumors, a basis of photodynamic therapy, and to possible pH-mediated relocalization of porphyrins among subcellular structures.
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Affiliation(s)
- K Kuzelová
- Laboratoire de Biophysique, INSERM U.201, CNRS U.A. 481, Muséum National d'Histoire Naturelle, Paris, France
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Ricchelli F. Photophysical properties of porphyrins in biological membranes. JOURNAL OF PHOTOCHEMISTRY AND PHOTOBIOLOGY. B, BIOLOGY 1995; 29:109-18. [PMID: 7472807 DOI: 10.1016/1011-1344(95)07155-u] [Citation(s) in RCA: 176] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/25/2023]
Abstract
This review illustrates the photophysical properties of some porphyrins, especially those used for biomedical applications, in relation to their photosensitizing efficiency in biological membranes. Porphyrin absorption and luminescence properties are mainly examined. The factors influencing the affinity of porphyrins for biological membranes, including the dye hydrophobicity, the charge and aggregation state, the pH of the medium and the physicochemical properties of the dye environment, are discussed. These factors determine the differences in the photophysical properties of porphyrins in biological membranes. Particular attention is paid to the porphyrin aggregation state: only monomeric species and possibly planar end-to-end aggregates are endowed with significant photosensitizing ability. Many conclusions presented are based on data obtained on membrane model systems such as micelles or liposomes which can mimic specific situations occurring in cells.
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Affiliation(s)
- F Ricchelli
- CNR Centre of Metalloproteins, Department of Biology, University of Padova, Italy
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