A proof-of-concept study using a graphene oxide-bovine serum albumin nanocomposite-based electrochemical aptasensor...

Salmonella Typhimurium (ST) is an important food-borne pathogen, particularly in chicken meat, making its rapid detection essential for food safety. Conventional detection methods are slow and equipment-intensive, creating the need for sensitive and portable alternatives. We developed a rapid, ultrasensitive, and portable electrochemical aptasensor platform for detecting ST in samples extracted from chicken meat. The sensor employed graphene oxide-bovine serum albumin (GO-BSA) nanocomposite to enhance electrode biocompatibility, stability, and aptamer immobilization. A specific NH₂-modified DNA aptamer targeting ST allowed direct binding without prior extraction. Fabrication steps included GO-BSA drop-casting, aptamer immobilization, and BSA blocking before ST binding. The sensor operates on a signal-off mechanism, measured via differential pulse voltammetry (DPV), where the aptamer-ST complex formation reduces the redox signal of [Fe(CN)₆]³^-/^4- due to insulation and electrostatic repulsion. The aptasensor demonstrated excellent sensitivity (limit of detection 3 CFU/mL) and high specificity. Performance validation using spiked samples extracted from chicken meat confirmed the effective detection of ST in a complex matrix, aligning with the results obtained through culture-based methods. The sensor also maintained good stability for up to 28 days at 4 °C. These results showed that aptasensors can be a rapid, cost-effective, and field-deployable tool for monitoring foodborne pathogens.