Detection of Bacterial Rhamnolipid Toxin by Redox Liposome Single Impact Electrochemistry

Abstract

The detection of Rhamnolipid virulence factor produced by Pseudomonas aeruginosa involved in nosocomial infections is reported by using the redox liposome single impact electrochemistry. Redox liposomes based on 1,2dimyristoyl-sn-glycero-3-phosphocholine as a pure phospholipid and potassium ferrocyanide as an encapsulated redox content are designed for using the interaction of the target toxin with the lipid membrane as a sensing strategy. The electrochemical sensing principle is based on the weakening of the liposomes lipid membrane upon interaction with Rhamnolipid toxin which leads upon impact at an ultramicroelectrode to the breakdown of the liposomes and the release/electrolysis of its encapsulated redox probe. We present as a proof of concept the sensitive and fast sensing of a submicromolar concentration of Rhamnolipid which is detected after less than 30 minutes of incubation with the liposomes, by the appearing of current spikes in the chronoamperometry measurement.

Recent advances in single liposome electrochemistry

“…The liposome size distribution obtained from the charge by integration of the current spikes is also in agreement with dynamic light scattering data, confirming that the observed events signal are related to single impacts of redox DMPC liposome onto UME [14,15]. This characteristic specific to the redox DMPC liposomes is recently used for detecting the lowest concentration of Rhamnolipid virulence factor produced by Pseudomonas aeruginosa pathogenic bacteria reported in literature, by using the ability of the toxin to act as a biosurfactant on the liposome lipid membrane [7]. In this proof of concept based on the redox DMPC liposome single impact electrochemistry, the lowest limit of detection of Rhamnolipid toxin (500 nM) is detected in less than 30 minutes [7].…”

“…This characteristic specific to the redox DMPC liposomes is recently used for detecting the lowest concentration of Rhamnolipid virulence factor produced by Pseudomonas aeruginosa pathogenic bacteria reported in literature, by using the ability of the toxin to act as a biosurfactant on the liposome lipid membrane [7]. In this proof of concept based on the redox DMPC liposome single impact electrochemistry, the lowest limit of detection of Rhamnolipid toxin (500 nM) is detected in less than 30 minutes [7].…”

“…Furthermore, the development of resistive-pulse sensing method using nanopipettes and nanopore microelectrodes is an efficient strategy for improving control and sensitivity in the redox liposomes single impact electrochemistry [47][48][49]. Nowadays, the trend is to use the versatility of the redox liposomes properties in terms of lipid membrane composition and encapsulated content, added to the sensitivity of the reactor method for extending single vesicle impact electrochemistry to sensing purposes [7,46,50].…”

“…Even if several techniques such as cryo-transmission electron microscopy, atomic force microscopy, dynamic light scattering and nanoparticle tracking analysis have been developed for liposomes analysis, the main advantages of single entities label-free electrochemical analysis nevertheless remain the high time resolution and sensitivity that allow to characterize several properties (size distribution, surface charge, and liposomes concentration) [3,4]. Since 2016, the single liposome electrochemistry has been increasingly studied and its applications highly extended [5][6][7][8].…”

“…In the present review, we will focus on the recent advances in single liposome electrochemistry including single-vesicle electrochemical events with the exocytosis process [11][12][13], electrochemical single impacts of synthetic redox liposomes [7,14,15], and the electroanalysis of single giant unilamellar vesicle (GUV) [16,17]. We will present these three different electroanalytical techniques and discuss their current limitations and applications through different recent examples.…”