Issue 18, 2020

Controlled molecular architectures in microfluidic immunosensors for detecting Staphylococcus aureus

Abstract

Detection of pathogenic microorganisms is essential for food quality control and diagnosis of various diseases, which is currently performed with high-cost, sophisticated methods. In this paper, we report on a low-cost detection method based on impedance spectroscopy to detect Staphylococcus aureus (S. aureus). The immunosensors were made with microfluidic devices made of interdigitated electrodes coated with layer-by-layer (LbL) films of chitosan and chondroitin sulfate, on which a layer of anti-S. aureus antibodies was adsorbed. The limit of detection was 2.83 CFU mL−1 with a limit of quantification of 9.42 CFU mL−1 for immunosensors with 10-bilayer LbL films. This level of sensitivity is sufficient to detect traces of bacteria that cause mastitis in milk, which we have confirmed by distinguishing milk samples containing various concentrations of S. aureus from pure milk and milk contaminated with Escherichia coli (E. coli) and Salmonella. Distinction of these samples was made possible by projecting the electrical impedance data with the interactive document mapping (IDMAP) technique. The high sensitivity and selectivity are attributed to the highly specific interaction with anti-S. aureus antibodies captured with polarization-modulated reflection absorption spectroscopy (PM-IRRAS), with adsorption on the antibodies explained with the Langmuir–Freundlich model. Since these immunosensors are stable for up to 25 days and detection measurements can be made within minutes, the methodology proposed is promising for monitoring S. aureus contamination in the food industry and hospitals, and in detecting bovine mastitis.

Graphical abstract: Controlled molecular architectures in microfluidic immunosensors for detecting Staphylococcus aureus

Supplementary files

Article information

Article type
Paper
Submitted
09 Apr 2020
Accepted
31 Jul 2020
First published
06 Aug 2020

Analyst, 2020,145, 6014-6023

Controlled molecular architectures in microfluidic immunosensors for detecting Staphylococcus aureus

A. C. Soares, J. C. Soares, V. C. Rodrigues, O. N. Oliveira and L. H. Capparelli Mattoso, Analyst, 2020, 145, 6014 DOI: 10.1039/D0AN00714E

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