Published September 1, 2020 | Version Published
Journal article Open

Detection of Pseudomonas aeruginosa quorum sensing molecules at an electrified liquid|liquid micro-interface through facilitated proton transfer

  • 1. The Bernal Institute and Department of Chemical Sciences, School of Natural Sciences, University of Limerick (UL), Limerick V94 T9PX, Ireland
  • 2. Memorial University of Newfoundland, Chemistry Department, 283 Prince Philip Dr., St. John's, NL Canada A1B 3X7
  • 3. School of Chemistry and Analytical and Biological Chemistry Research Facility (ABCRF), University College Cork, College Road, Cork, Ireland


Miniaturization of electrochemical detection methods for point-of-care-devices is ideal for their integration and use within healthcare environments. Simultaneously, the prolific pathogenic bacteria Pseudomonas aeruginosa poses a serious health risk to patients with compromised immune systems. Recognizing these two factors, a proof-of-concept electrochemical method employing a micro-interface between water and oil (w/o) held at the tip of a pulled borosilicate glass capillary is presented. This method targets small molecules produced by P. aeruginosa colonies as signalling factors that control colony growth in a pseudo-multicellular process known as quorum sensing (QS). The QS molecules of interest are 4‐hydroxy‐2‐heptylquinoline (HHQ) and 2‐heptyl‐3,4‐dihydroxyquinoline (PQS, Pseudomonas quinolone signal). Hydrophobic HHQ and PQS molecules, dissolved in the oil phase, were observed electrochemically to facilitate proton transfer across the w/o interface. This interfacial complexation can be exploited as a facile electrochemical detection method for P. aeruginosa and is advantageous as it does not depend on the redox activity of HHQ/PQS. Interestingly, the limit-of-linearity is reached as [H+]≈[ligand]. Density functional theory calculations were performed to determine the proton affinities and gas-phase basicities of HHQ/PQS, as well as elucidate the likely site of stepwise protonation within each molecule.


E.D.B. acknowledges funding received from an Irish Research Council Government of Ireland Postgraduate Scholarship Award (grant number GOIPG/2016/1217). This publication has emanated from research by M.D.S. and A.F.M.-O. supported by the European Research Council through a Starting Grant (agreement no. 716792) and in part by a research grant from Science Foundation Ireland (SFI) (grant number 13/SIRG/2137). G.M.G. and R.S. thank the Irish Research Council for funding. T.J.S is grateful to NSERC for funding with an NSERC Discovery Grant.



Files (1.2 MB)

Name Size Download all
778.4 kB Preview Download
436.0 kB Preview Download

Additional details


Designing Reactive Functionalised Soft Interfaces _ Self-healing soft materials for solar energy conversion, energy storage, and sustainable low cost hydrogen production 13/SIRG/2137
Science Foundation Ireland
SOFT-PHOTOCONVERSION – Solar Energy Conversion without Solid State Architectures: Pushing the Boundaries of Photoconversion Efficiencies at Self-healing Photosensitiser Functionalised Soft Interfaces 716792
European Commission