Rapid and Selective Detection of Foodborne Pathogens Using a Disposable Bio-sensing System Designed by Stepwise Antibody Immobilization on AuNPs@Cu-MOF Nanocomposite

There is an urgent need to provide a rapid and selective method to analyze food and water samples contaminated with Staphylococcus aureus since it is one of the most potential food and waterborne pathogens. Thus, a portable bio-sensing system and disposable bacterial-sensor chips consisted of anti-S. aureus@MPA/AuNPs-Cu-MOF@SPE were designed, fabricated, and applied for 20-min-based analysis of food and water samples. In this regard, screen-printed electrodes (SPEs) were functionalized with a new synthesized copper-metal organic framework (Cu-MOF) conjugated with gold nanoparticles (AuNPs) to effectively promote the chemical immobilization of the bio-receptor (anti-S. aureus antibody) onto the sensor matrix using the mercaptopropionic acid (MPA) as a chemical cross-linker. Subsequently, parameters affecting the bacterial-sensing efficacy were studied and optimized. Accordingly, high sensitivity was obtained with a wide dynamic linear range from 1 × 10 to 1 × 10⁷ colony forming units per milliliter (CFU/mL) with correlation coefficient (R²) of 0.990, limit of detection and limit of quantification of 0.132 CFU/mL, and 0.440 CFU/mL, respectively. High selectivity was provided since no electrochemical signals were obtained from various non-targeting strains of common pathogens, including the Pseudomonas aeruginosa, Escherichia coli, Salmonella enterica, Streptococcus mutans, and Enterococcus faecalis. Eventually, the newly developed handheld bacterial-sensing platform was applied for the rapid analysis of S. aureus in food and water samples.