Analytical and Bioanalytical Chemistry

, Volume 410, Issue 19, pp 4737–4748 | Cite as

Miniaturized dispersive liquid-liquid microextraction and MALDI MS using ionic liquid matrices for the detection of bacterial communication molecules and virulence factors

  • Jan Leipert
  • Ingrid Bobis
  • Sabine Schubert
  • Helmut Fickenscher
  • Matthias Leippe
  • Andreas TholeyEmail author
Research Paper
Part of the following topical collections:
  1. Ionic Liquids as Tunable Materials in (Bio)Analytical Chemistry


The identification and quantification of molecules involved in bacterial communication are major prerequisites for the understanding of interspecies interactions at the molecular level. We developed a procedure allowing the determination of 2-heptyl-4(1H)-quinolone (HHQ) and 2-heptyl-3-hydroxy-4(1H)-quinolone (PQS) and the virulence factor pyocyanin (PYO) formed by the Gram-negative bacterium Pseudomonas aeruginosa. The method is based on dispersive liquid-liquid microextraction from small supernatant volumes (below 10 μL) followed by quantitative matrix-assisted laser desorption/ionization (MALDI) mass spectrometry (MS). The use of ionic liquid matrix led to a lowered limit of detection for pyocyanin and, due to suppression of matrix background signals, easy to interpret mass spectra compared to crystalline matrices. Using an isotope-labeled pyocyanin standard synthesized in small-scale synthesis, quantitative analysis spanning approximately one order of magnitude (0.5 to 250 fmol) was feasible. The method was successfully applied to the detection of the signaling molecules PQS and HHQ in cultures of P. aeruginosa strains isolated from sputum of cystic fibrosis patients and allowed a highly sensitive quantification of PYO from these cultures. Hence, the developed method bears the potential to be used for screening purposes in clinical settings and will help to decipher the molecular basis of bacterial communication.

Graphical abstract

Ionic liquid matrices for the detection and quantification of the toxin pyocyanin and other signaling molecules from P. aeruginosa by MALDI MS.


Biofilm Cystic fibrosis Pseudomonas aeruginosa Pyocyanin Quorum sensing Resistance 



This work was funded by the SFB1182 “Function and Origin of Metaorganisms,” project A1, and by the Cluster of Excellence “Inflammation at Interfaces.” We thank Nadja Schmitz for the assistance with the experiments and Heidrun Ließegang as well as Corinna Wriedt for the technical help in the preparation of the bacterial cultures.

Compliance with ethical standards

Conflict of interest

The authors declare that they have no conflicts of interest.

Ethical approval

This article does not contain any studies with human or animal subjects. Based on the approval of the Ethics committee (Ethik-Kommission) of the Medical Faculty of the Christian Albrecht University of Kiel (D479/15 amendment of Aug 18, 2016) and according to the ethical standards, sputum samples were obtained from patients with cystic fibrosis after informed consent and Pseudomonas aeruginosa isolates were cultivated.

Supplementary material

216_2018_937_MOESM1_ESM.pdf (1.6 mb)
ESM 1 (PDF 1668 kb)


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Copyright information

© Springer-Verlag GmbH Germany, part of Springer Nature 2018

Authors and Affiliations

  • Jan Leipert
    • 1
  • Ingrid Bobis
    • 2
  • Sabine Schubert
    • 3
  • Helmut Fickenscher
    • 3
  • Matthias Leippe
    • 4
  • Andreas Tholey
    • 1
    Email author
  1. 1.Systematic Proteome Research & Bioanalytics, Institute for Experimental MedicineUniversity of KielKielGermany
  2. 2.Department of Internal MedicineUniversity Hospital Schleswig-HolsteinKielGermany
  3. 3.Institute for Infection MedicineUniversity of Kiel and University Hospital Schleswig-HolsteinKielGermany
  4. 4.Zoological Institute, Comparative ImmunobiologyUniversity of KielKielGermany

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