Excited Fluorophores Enhance the Opening of Vesicles at Electrode Surfaces in Vesicle Electrochemical Cytometry. Issue 48 (2nd November 2016)

• Record Type: Journal Article
• Authors: Najafinobar, Neda; Lovrić, Jelena; Majdi, Soodabeh; Dunevall, Johan; Cans, Ann‐Sofie; Ewing, Andrew
• Is Part Of: Angewandte Chemie international edition. Volume 55:Issue 48(2016)
• Page Start: 15081
• Page End: 15085
• Publication Date: 2016-11-02
• Subjects: electroporation -- chemical cytometry -- fluorophores -- fusion pores -- vesicles; Chemistry -- Periodicals; 540
• DOI: 10.1002/anie.201609178
• Languages: English
• ISSNs: 1433-7851

Abstract

Abstract: Electrochemical cytometry is a method developed recently to determine the content of an individual cell vesicle. The mechanism of vesicle rupture at the electrode surface involves the formation of a pore at the interface between a vesicle and the electrode through electroporation, which leads to the release and oxidation of the vesicle's chemical cargo. We have manipulated the membrane properties using excited fluorophores conjugated to lipids, which appears to make the membrane more susceptible to electroporation. We propose that by having excited fluorophores in close contact with the membrane, membrane lipids (and perhaps proteins) are oxidized upon production of reactive oxygen species, which then leads to changes in membrane properties and the formation of water defects. This is supported by experiments in which the fluorophores were placed on the lipid tail instead of the headgroup, which leads to a more rapid onset of vesicle opening. Additionally, application of DMSO to the vesicles, which increases the membrane area per lipid, and decreasing the membrane thickness result in the same enhancement in vesicle opening, which confirms the mechanism of vesicle opening with excited fluorophores in the membrane. Light‐induced manipulation of membrane vesicle pore opening might be an attractive means of controlling cell activity and exocytosis. Additionally, our data confirm that in experiments in which cells or vesicle membranes are labeled for fluorescence monitoring, the properties of the excited membrane change substantially. Abstract : Vesicle electrochemical cytometry has been developed as a novel technique to measure the content of individual vesicles. It is proposed that bringing an excited fluorophore into close contact with the membrane enhances vesicle opening through the oxidation of membrane lipids (and perhaps proteins), which leads to a more disrupted membrane and both better adsorption of vesicles to the electrode surface and an electroporation‐formed fusion pore.