A highly sensitive and specific Gold Electrode-Based electrochemical immunosensor for rapid On-Site detection of Salmonella enterica

This study introduces an advanced electrochemical-based biosensor for detecting Salmonella enterica serovar typhimurium (S. typhimurium). The design involves immobilizing anti-Salmonella antibodies on a gold (Au) electrode using self-assembled monolayers (SAM) formation with mercaptoacetic acid (MAA). The subsequent activation using EDC/NHS ensures the stable attachment of the antibodies, a crucial step for maintaining the sensitivity and specificity of the biosensor over extended periods. When Salmonella bacteria bind to the immobilized antibodies, there is an alteration in the electrode's electrical properties. This change is detectable using cyclic voltammetry (CV), with the peak current observed in the voltammogram being proportional to the Salmonella concentration, thus facilitating quantification. We evaluated various parameters influencing biosensor performance, including antibody immobilization, selectivity, sensitivity, and specificity. Remarkably, our biosensor demonstrated high sensitivity, accurately detecting as few as 10 colony-forming units (CFU)/mL of S. typhimurium within a twenty-minute window, with no cross-reactivity to other pathogens. This sensitivity surpasses many standard techniques for Salmonella detection, such as culture-based methods, PCR, ELISA, and microscopy. Our biosensor offers rapid detection compared to conventional methods, which are precise but often time-consuming and require specialized equipment and trained personnel. Its performance in artificially contaminated food and water samples was consistent with traditional methods, underscoring its reliability for practical applications. Given its portability, this biosensor has immense potential for on-site, point-of-need detection of S. typhimurium, providing a more efficient alternative to traditional techniques that require days for results and specialized training.