Fig 1.
The flow chart diagram of synthesis of QDs (a), QDs-ssDNA2 (b) and aptamer@MNPs (c).
Fig 2.
Schematic diagram of (a) the synthesis of streptavidin magnetic nanoparticles and carboxyl CdTe QDs, (b) illustration of the detection of S. Typhimurium.
Fig 3.
TEM (a) and HRTEM (b) images of CdTe QDs.
Fig 4.
(a) Fluorescence spectra of QDs (curve a) and QDs@ssDNA2 (curve b); (b) UV-vis absorption spectrum of QDs and QDs@ssDNA2.
Fig 5.
UV-vis absorption spectrum of MNPs@aptamer (curve a) and aptamer (curve b).
Fig 6.
(a) UV-visible absorption spectrum of 10 μL of 1 mg•mL-1 streptavidin-coated MNPs decorated with 50 μL of 10 nM aptamer. (b) Fluorescence spectra of different concentrations (from 70 μL to 10 μL) of ssDNA2@CdTe QDs of 30 μg·mL-1 ssDNA2@CdTe QDs. (c) Fluorescence spectra of aptamer&QDs-ssDNA2@MNPs after different incubation times with S. Typhimurium. (d) Fluorescence spectra of aptamer&QDs-ssDNA2@MNPs incubated with S. Typhimurium at different incubation temperatures.
Fig 7.
(a) Fluorescence spectra of aptasensors with different concentrations (from a to h: 1010, 107, 105, 104, 103, 102, 10, 0 cfu•mL-1) of S. Typhimurium; (b) calibration curve of the fluorescence intensity of the QDs@ssDNA2 at 612 nm for S. Typhimurium detection.
Table 1.
Comparison of different methods for the detection of S. Typhimurium.
Fig 8.
Specificity result for the detection of S. enteritidis, S. aureus, E. coli O157:H7, L. monocytogenes, B. cereus, P. aeruginosa and S. Typhimurium.
Table 2.
Determination of S. Typhimurium in real samples.