Rapid detection of Salmonella enterica in raw milk samples using Stn gene-based biosensor

In this study, a DNA-based nanosensor using specific NH₂ labeled single standard probe was developed against stn gene of Salmonella enterica in milk samples. The single-stranded DNA probe was immobilized on carboxylated multiwalled carbon nanotube and gold nanoparticle (c-MWCNT/AuNP) electrode using 1-Ethyl-3-(3-dimethylaminopropyl) carbodiimide (EDC): N-hydroxy succinimide-based cross-linking chemistry. Electrochemical characterization was performed using cyclic voltammetry (CV) and Differential Pulse Voltammetry (DPV) techniques. The electrode surface at each step of fabrication was characterized using scanning electron microscopy. The sensitivity and lower limit of detection were found to be 728.42 (μA/cm²)/ng and 1.8 pg/6 μl (0.3 pg/ml), respectively, with regression coefficient (R ²) of 0.843 using DPV. The sensor was further validated using raw and artificial milk samples, and results were compared with conventional methods of detection. The developed sensor was found to be highly sensitive and stable up to 6 months, with only 10% loss of initial peak current in CV analysis on storage at 4 °C.