Single-Impact Electrochemistry of Redox Liposomes for the Detection of Virulence Factors

Abstract

Early detection of pathogens is a key factor for the successful therapy of infectious diseases. Some of the pathogenic bacteria involved in diseases interact with the host by producing compounds that are toxic or disruptive to the cells. As these virulence factors can be easier to spot than the pathogen, strategies of detection can be focused on these released compounds to identify the pathogenic bacterium.[1] Liposomes are vesicles composed of a lipid bilayer membrane, and as such are often used to mimic living cells. Here, the strategy consists in making redox liposomes by encapsulating an electroactive probe in their inner cavity, which will be detected at the electrode.[2] Virulence factors interacting with the vesicles increase the permeability of the lipid membrane and the contents of the liposomes are released over time. This redox probe is then detected with an electrode polarized at the appropriate potential. This work aims to study the single-impact electrochemistry of redox liposomes in different conditions. Previous results indicate that the addition of a surfactant to a liposomal suspension leads to their rupture when they stochastically collide with an ultramicroelectrode.[3] Similarly, virulence factors increase their release or electrolysis of contents upon impact with an ultramicroelectrode.[4] Chronoamperometry measurements recorded at the ultramicroelectrode polarized at the redox potential of the electrochemical probe show impact events (vesicle blocking) and opening events (vesicle reactor) when the encapsulated redox probe is released by the liposome, which are traced back to the presence of pathogenic bacteria.