title: The effect of solution electrolytes on the uptake of photosensitizers by liposomal membranes: a salting-out effect.
abstract: In this study we investigated, spectroscopically, the effect of electrolytes on the partitioning of hematoporphyrin IX (HP) and hypericin (Hy) into non-charged lipid vesicles. Our aim was to assess the salting-out effect of electrolytes on membrane-partitioning. We titrated aqueous solutions of HP and Hy with lecithin liposomes, at different concentrations of several monovalent and divalent electrolytes in the suspension. The partitioning constant of HP to lecithin liposomes increased from 3.3 (mL/mg) in water containing only 5mM buffer to 8.7 (mL/mg) at 0.36M KCl. KF had a similar effect. NaCl caused a 3-fold increase in the partitioning of Hy to liposomes. MgSO(4) and MgCl(2) also increased the partitioning of HP, by a factor of more than 4 and this occurred already at 0.03M concentration. We analyze the comparative effects of the electrolytes in relation to the Hofmeister series. The salting-out effect could be utilized to enhance the uptake of HP and Hy, and possibly other photosensitizers as well, by artificial and natural membranes.
authors.affiliation: Department of Physics and Nano Medicine Research Center, Institute of Nanotechnology and Advanced Materials, Bar Ilan University, Ramat Gan 52900, Israel.
authors.forename: Refael
authors.initials: R
authors.lastname: Minnes
authors.forename: Shany
authors.initials: S
authors.lastname: Ytzhak
authors.forename: Hana
authors.initials: H
authors.lastname: Weitman
authors.forename: Benjamin
authors.initials: B
authors.lastname: Ehrenberg
mesh_terms: D002627:Chemistry, Physical / Q000379:methods; D004573:Electrolytes / Q000737:chemistry*; D006863:Hydrogen-Ion Concentration; D007700:Kinetics; D054709:Lecithins / Q000737:chemistry; D008055:Lipids / Q000737:chemistry; D008081:Liposomes / Q000737:chemistry*; D008566:Membranes / Q000737:chemistry*; D008956:Models, Chemical; D017319:Photosensitizing Agents / Q000494:pharmacology; D011189:Potassium Chloride / Q000737:chemistry; D012965:Sodium Chloride / Q000494:pharmacology; D012996:Solutions; D013056:Spectrophotometry, Ultraviolet / Q000379:methods; D014867:Water / Q000737:chemistry
chemical_list: D004573:Electrolytes; D054709:Lecithins; D008055:Lipids; D008081:Liposomes; D017319:Photosensitizing Agents; D012996:Solutions; D014867:Water; D012965:Sodium Chloride; D011189:Potassium Chloride