Electrochemical detection of Salmonella using an invA genosensor on polypyrrole-reduced graphene oxide modified glassy carbon electrode and AuNPs-horseradish peroxidase-streptavidin as nanotag

A rapid and sensitive electrochemical biosensor was constructed to detect Salmonella using invA gene biosensor. The biosensing was based on polyrrole-reduced graphene oxide (PPy-rGO) nanocomposite modified glassy carbon electrode (GCE) and signal amplification with horseradish peroxidase-streptavidin biofunctionalized gold nanoparticles (AuNPs-HRP-SA). PPy-rGO was prepared at 60 °C by chemical reduction of PPy-functionalized graphene oxide (PPy-GO) that was synthesized by in situ polymerization at room temperature . The detection signal was amplified via enzymatic reduction of H 2 O 2 in the presence of hydroquinone (HQ) using AuNPs-HRP-SA as nanotag. Under optimal conditions, the differential pulse voltametric (DPV) signal from the biosensor was linearly related to the logarithm of target invA gene concentrations from 1.0 × 10 −16 to 1.0 × 10 −10  M, and the limit of detection (LOD) was 4.7 × 10 −17  M. The biosensor can also detect Salmonella in the range of 9.6 to 9.6 × 10 4   CFU  mL −1 , with LOD of 8.07 CFU mL −1 . The biosensor showed good regeneration ability , acceptable selectivity , repeatability and stability, which bode well as an alternative method for Salmonella screening.