Electrochemical Properties of Phospholipid Monolayers at Liquid–Liquid Interfaces

Abstract

Biomembrane models built at the interface between two immiscible electrolytes (ITIES) are useful systems to study phenomena of biological relevance by means of their electrochemical processes. The unique properties of ITIES allow one either to control or measure the potential difference across the biomimetic membranes. Herein we focus on phospholipid monolayers adsorbed at liquid-liquid interfaces, and besides discussing recent developments on the subject, we describe electrochemical techniques that can be used to get insight on the interfacial processes and electrostatic properties of phospholipid membranes at the ITIES. In particular, we examine the electrochemical and physicochemical properties of (modified) phospholipid monolayers and their interaction with other biologically relevant compounds. The use of liquid-liquid electrochemistry as a powerful tool to characterize drug properties is outlined. Although this review is not a survey of all the work in the field, it provides a comprehensive referencing to current research.

Phospholipids at the Interface: Current Trends and Challenges

“…Ion transfer through the PL monolayer was studied in details by Kontturi and co-workers [53–55]; the role of aqueous cations on the stability of the PL monolayer was investigated by Kakiuchi et al [56,57]; and work on the dynamics of PL monolayer at ITIES was undertaken by Samec et al [58]. For more information on the behavior of phospholipids at ITIES, one can be referred to the recent review article by Santos et al [59]. …”

Voltammetry of proteins at liquid–liquid interfaces

“…For many years, the formation and stability of lipid monolayers at the ITIES has been examined, 45 noting that the lipid monolayers are formed because of the tendency of the lipid to assemble at the ITIES with its polar head facing the aqueous phase and its non-polar tail directed into the organic phase.…”

Single Fusion Events at Polarized Liquid–Liquid Interfaces

“…Also, this will enable the determination of the lipophilicity of ionic compounds even with respect to media of very low dielectric constant. Moreover, with the use of phospholipid‐modified ITIES, understanding can be gained about charge transfer and uptake‐release processes of biological interest and about interactions of biomembranes with (sub)micrometric entities. Quantitative applications call first for the identification and modelling of the governing mass transport, electrical and thermodynamic forces in these systems and of the dynamics of the fusion.…”