A novel method for visual detection of Salmonella based on Fe3O4 magnetic beads and AuNPs

• 1、School of Food Science and Technology,Jiangnan University,JiangSu WuXi 214122

Abstract：In this paper, we established a novel method for visual detection of Salmonella based on Fe3O4 magnetic beads and colorimetric effect of AuNPs. We chose the complementary oligonucleotide sequences of bases which Salmonella can recognized specifically, then modified the surfaces of Fe3O4 magnetic beads and AuNPs with them. So that, we've constructed the capture probe and the display probe. It would form a special "sandwich" structure at the time we added Salmonella target DNA into the system according to the principle of complementary base pairing. As the color of AuNPs changes according to the degree of aggregation of AuNPs, if we added more target DNA, more and more AuNPs aggregated, the color of AuNPs would vary from red to blue. So that we realized the visual detection of Salmonella. Under the optimal conditions, it showed a good linear relationship when the concentrations of target DNA was in the range of 1 pmol/L to 1500 pmol/L, the linear regression equation was y=0.007x+0.2535 (R2=0.9983), the lowest detection limit was 1 pmol/L. And it showed a good linear relationship when the concentrations of Salmonella was in the range of 30 to 8600 cfu/mL, the linear regression equation was y=0.0001x+0.3083 (R2=0.9962), the lowest detection limit was 23 cfu/mL. The specificity and the spiked recovery experiments proved that this method could be used for the detection of actual samples.

Keywords： food analysis magnetic beads AuNPs visual detection Salmonella