A Novel Staphylococcal Enterotoxin Q Immunosensor Prepared with Self-Assembly Method Based on Horseradish Peroxidase and Double-Layer Gold Nanoparticles

A novel and green electrochemical immunosensor for detection of Staphylococcal enterotoxin Q (SEQ), a toxic superantigen that can induce severe food poisoning and even fatal conditions, was developed by fixing double-layer gold nanoparticles (AuNPs), horseradish peroxidase, and thionin-chitosan composite membrane on the glassy carbon electrode surface. Under optimal conditions, the developed immunosensor showed a wide linear range from 0.1 to 100 pg mL(-1) (R (2) = 0.992) for SEQ with a low detection limit of 0.046 pg mL(-1) (S/N = 3). The immunosensor had good specificity (no significant cross reaction with lipopolysaccharides, bovine IgG, Escherichia coli, or other common biological components), and remained fairly stable (over 87 % of the original signal response after stored for 20 days at 4 A degrees C). In addition, the immunosensor was successfully applied to milk sample detection and demonstrated with high recoveries (from 91 to 113 %). In conclusion, the developed electrochemical immunosensor can supply a green and feasible tool for detection of SEQ in food.