Abstract
The detection of pathogenic bacteria remains a challenge for the struggle against biological weapons, nosocomial diseases, and for food safety. In this research, our aim was to develop an easy-to-use electrochemical immunosensor for the detection of pathogenic Staphylococcus aureus ATCC25923. The biosensor was elaborated by the immobilization of anti-S. aureus antibodies using a self-assembled monolayer (SAMs) of 3-Mercaptopropionic acid (MPA). These molecular assemblies were spontaneously formed by the immersion of the substrate in an organic solvent containing the SAMs that can covalently bond to the gold surface. The functionalization of the immunosensor was characterized using two electrochemical techniques: cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS). Here, the analysis was performed in phosphate buffer with ferro/ferricyanide as the redox probe. The EIS technique was used for affinity assays: antibody-cell binding. A linear relationship between the increment in the electron transfer resistance (RCT) and the logarithmic value of S. aureus concentration was observed between 10 and 106 CFU/mL. The limit of detection (LOD) was observed at 10 CFU/mL, and the reproducibility was calculated to 8%. Finally, a good selectivity versus E. coli and S. epidermidis was obtained for our developed immunosensor demonstrating its specificity towards only S. aureus.
Highlights
Staphylococci are constantly present all around us
After thorough cleansing and immersion into Mercaptopropionic acid (MPA) ethanolic solution, the gold electrode was characterized by water contact angles
self-assembled monolayers (SAMs), the antibody binding, and pathogenic bacteria detection. The performance of this sensor was evaluated in terms of its sensitivity, limit of detection, dynamic range, reproducibility, and specificity for S. aureus bacteria
Summary
Staphylococci are constantly present all around us. They are most frequently found in common infections of skin, e.g., after shaving, around the nose, and in children’s scraped knees. It is the bacteria most frequently involved in nosocomial infections. Some strains have the possibility under certain conditions to produce enterotoxins responsible for food poisoning. This production implies the presence of large quantities of germs in food [1].
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