Fe3O4@Au Core–Shell Magnetic Nanoparticles for the Rapid Analysis of E. coli O157:H7 in an Electrochemical Immunoassay

• Published in: Biosensors (Basel) Vol. 13; no. 5; p. 567
• Main Authors: Bazsefidpar, Shayesteh, Freitas, Maria, Pereira, Clara R., Gutiérrez, Gemma, Serrano-Pertierra, Esther, Nouws, Henri P. A., Matos, María, Delerue-Matos, Cristina, Blanco-López, María Carmen
• Format: Journal Article
• Language: English
• Published: Basel MDPI AG 22.05.2023; MDPI
• Subjects: Acids; amperometric biosensor; Antibodies; Antigens; Bacteria; Bioassays; Biosensors; E coli; Electrochemical analysis; Electrochemistry; Escherichia coli; Ethanol; Food contamination & poisoning; Gastrointestinal system; Gastrointestinal tract; Gold; Horseradish peroxidase; Immunoassay; immunomagnetic assay; Iron oxides; Listeria; Listeria monocytogenes; magnetic core–shell nanoparticles; Magnetic fields; Nanomaterials; Nanoparticles; p60 Protein; pathogenic bacteria; Peroxidase; Potassium; Proteins; SPCE; Synthesis; Toxicity; Transducers; United States > US; Norway; Spain
• ISSN: 2079-6374; 2079-6374
• DOI: 10.3390/bios13050567

Escherichia coli (E. coli) O157:H7 is a pathogenic bacterium that causes serious toxic effects in the human gastrointestinal tract. In this paper, a method for its effective analytical control in a milk sample was developed. To perform rapid (1 h) and accurate analysis, monodisperse Fe3O4@Au magnetic nanoparticles were synthesized and used in an electrochemical sandwich-type magnetic immunoassay. Screen-printed carbon electrodes (SPCE) were used as transducers, and electrochemical detection was performed by chronoamperometry using a secondary horseradish peroxidase-labeled antibody and 3,3′,5,5′-tetramethylbenzidine. This magnetic assay was used to determine the E. coli O157:H7 strain in the linear range from 20 to 2 × 106 CFU/mL, with a limit of detection of 20 CFU/mL. The selectivity of the assay was tested using Listeria monocytogenes p60 protein, and the applicability of the assay was assessed by analyzing a commercial milk sample, demonstrating the usefulness of the synthesized nanoparticles in the developed magnetic immunoassay.