Microconductometric immunosensor for label-free and sensitive detection of Gram-negative bacteria

• Published in: Biosensors & bioelectronics 2014-04, Vol.54, p.378-384
• Main Authors: El Ichi, Sarra, Leon, Fanny, Vossier, Ludivine, Marchandin, Helene, Errachid, Abdelhamid, Coste, Joliette, Jaffrezic-Renault, Nicole, Fournier-Wirth, Chantal
• Format: Article
• Language: English
• Subjects: Analytical chemistry; Antibodies, Immobilized - chemistry; Biological and medical sciences; Biosensing Techniques - methods; Biosensors; Biotechnology; Blood safety; Chemical Sciences; Conductometric transduction; Conductometry - methods; Fundamental and applied biological sciences. Psychology; Gram-negative bacteria; Gram-Negative Bacteria - isolation & purification; Gram-Negative Bacterial Infections - diagnosis; Gram-Negative Bacterial Infections - microbiology; Humans; Immunoassay - methods; Label free detection; Limit of Detection; Magnetite Nanoparticles - chemistry; Magnetite Nanoparticles - ultrastructure; Magneto-immunoassay; Methods. Procedures. Technologies; Various methods and equipments
• ISSN: 0956-5663; 1873-4235
• DOI: 10.1016/j.bios.2013.11.016

Blood safety is a global health goal. In developed countries, bacterial contamination of platelet concentrates is the highest infectious risk in transfusion despite the current preventive strategies. We aimed to develop a conductometric biosensor for the generic, rapid and sensitive detection of Gram-negative bacteria. Our strategy is based on immunosensors: addressable magnetic nanoparticles coupled with anti-LPS antibodies were used for the generic capture of Gram-negative bacteria. Bacterial capture was characterized by impedancemetric and microscopic measurements. The results obtained with conductometric measurements allowed real-time, sensitive detection of Escherichia coli or Serratia marcescens cultures from 1 to 103CFUmL−1. The ability of the immunosensor to detect Gram negative bacteria was also tested on clinically relevant strains. The conductometric immunosensor allowed the direct detection of 10–103CFUmL−1 of Pseudomonas aeruginosa and Acinetobacter baumannii strains that were undetectable using standard immunoblot methods. Results showed that the conductometric response was not inhibited in 1% serum. •Immunosensors were functionalized with anti-LPS antibodies magnetic nanoparticles.•Conductometric measurements allow real-time, sensitive detection of Escherichia coli.•Detected bacterial concentrations are from 1 to 103CFUmL−1.•The immunosensor is able to detect Gram-negative clinically relevant strains.•Conductometric response was not inhibited in 1% serum.