Abstract:

Purpose: To establish a detection method with high sensitivity for Salmonella by cyclic voltammetry based on
Au/SiO2 signal amplification. Methods: The capture DNA and the display DNA, which are complementary with the target DNA were
modified onto the surface of indium tin oxide (ITO) electrode and the surface of Au/SiO2 nanoparticles. As results, capture probe and
display probe were constructed. A “sandwich” structure was constructed by capture DNA-target DNA-display DNA when Salmonella
target DNA was added into the system. As the content of Au/SiO2 was positively correlated with the concentration of the target DNA,
the peak current value of fully modified ITO could be changed by varying the concentration of the target DNA, so as to achieve the
purpose of detection. Results: Under the optimal conditions, the method showed a good linear relationship when the concentration
of target DNA was in the range of 10-11 to 10-7 mol/L, the linear regression equation was y = -0.000 3x + 0.000 1 (R2 = 0.998 9), and
the lowest limit of detection (LOD) was 6 pmol/L. And it showed a good linear relationship when the concentration of Salmonella
was in the range of 50 to 7 910 CFU/mL, the linear regression equation was y = -1.6×10-7x + 0.003 2 (R2 = 0.994 0), and the lowest
LOD was 35 CFU/mL. Conclusions: The specificity and spiked recovery experiments proved that this method could be used for the
detection of actual samples.

Key words: food analysis, Salmonella, gold nanoparticles, silicon dioxide (SiO2), cyclic voltammetry