Rapid and Sensitive Strategy for Salmonella Detection Using an InvA Gene-Based Electrochemical DNA Sensor

A rapid and sensitive strategy for the detection of Salmonella was proposed by integrating simple DNA extraction, specific polymerase chain reaction (PCR) with an invA gene-based electrochemical DNA sensor. The amplified target sequence of invA gene could be specifically captured on the sensing interface, and further hybridized with biotinylated detection probe to form a sandwich-type hybridization structure. The electrochemical signal was amplified by streptavidin-alkaline phosphatase (ST-AP), producing sensitive enzyme-catalyzed electrochemical DNA sensing. The fabrication and hybridization processes were characterized with electrochemical impedance spectroscopy (EIS), square wave voltammetry (SWV) and surface plasmon resonance (SPR). The designed DNA sensor could discriminate satisfactorily the complementary and mismatched oligonucleotides, indicating good selectivity. The linear calibration range for target DNA detection was from 1 pM to 10 nM with a detection limit of 0.5 pM, showing high sensitivity. Under optimal conditions, the proposed strategy could quantitatively detect Salmonella from 10 to 105 CFU mL-1 within 3.5 h. This strategy presented a simple, rapid and sensitive platform for Salmonella detection and would become a powerful tool for pathogenic microorganisms screening in clinical diagnostics, food safety, biothreat detection and environmental monitoring.