Establishment of a dual-signal sandwich sensor for detection of shigella sonnei based on truncated aptamers

Shigella Sonnei (S. sonnei) is a common foodborne pathogen causing intestinal diseases. In this study, a sandwich structured colorimetric and surface-enhanced Raman scattering (SERS) dual methods adaptation sensor was prepared for the detection of S. sonnei. Firstly, two aptamers, SS4.1-2 (Kd = 43.5 +/- 2.78 nM) and SP1-2.2 (Kd = 23.3 +/- 3.01 nM) with good specificity and affinity were obtained by truncation strategy. Then, Fe3O4@SiO2@Ag nanoparticles were utilized to capture bacteria, while Cu-TCPP (Fe)/AuNPs nanosheets were used as signal probes due to their oxidase activity and SERS signals. The detection limits of the aptasensor were as low as 37 CFU/mL for the colorimetric signal and 7 CFU/mL for SERS signal. Furthermore, the aptasensor was successfully applied to detect S. sonnei in real samples with 94.95-112.92% and 98.40-103.95% recoveries for colorimetric and SERS methods, respectively. A more rapid and accurate method to detect S. sonnei contamination in food was improved.