Lipid Membrane Permeability of Synthetic Redox DMPC Liposomes Investigated by Single Electrochemical Collisions

The electrochemical detection of synthetic redox DMPC (1,2-dimyristoyl-sn-glycero-3-phosphocholine) liposomes by single collisions at 10 μm diameter carbon and Pt ultramicroelectrodes (UMEs) is reported. To study the parameters influencing the lipid membrane opening/permeability, the electrochemical detection of single redox DMPC liposome collisions at polarized UMEs was investigated under different experimental conditions (addition of surfactant, temperature). The electrochemical responses recorded showed that the permeability of the DMPC lipid membrane (tuned by addition of Triton X-100 surfactant or by the increase of the solution temperature) is a key parameter for the liposome membrane electroporation process and hence for the release and oxidation of its redox content during the collision onto UMEs. The presence of ferrocenemethanol as an additional redox probe in the aqueous solution (at room temperature and without addition of surfactant) is also an interesting strategy to detect current spikes corresponding to single redox DMPC liposome collisions with K₃Fe(CN)₆/K₄Fe(CN)₆ as the encapsulated aqueous redox probe.