▎ 摘　　要

NOVELTY - Detecting Salmonella typhimuriumbased on fluorescent probe of nitrogen-sulfur co-doped graphene quantum dots, involves preparing signal probe solution by using nitrogen-sulfur co-doped graphene quantum dots modified by aminated aptamer, where aminated aptamer comprises nucleotide sequence of 40 base pairs, and preparing magnetic separation probe solution by using streptavidin magnetic beads modified by biotinylated aptamer, where biotinylated aptamer comprises nucleotide sequence of 40 base pairs, where the SEQ ID Nos are not defined. USE - Method for detecting Salmonella typhimurium based on fluorescence probe of nitrogen-sulfur co-doped graphene quantum dot. ADVANTAGE - The method enables to realize synchronous identification of Salmonella typhimurium, simple in operation, reduce the influence of sample matrix, low in cost, stable fluorescent, characteristics because of doping nitrogen in the quantum graphene, sulfur element, which effectively improves the fluorescent quantum graphene of the quantum dot, the detection sensitivity is improved to 11.9 cfu/mL, and has good application and popularization prospect. DETAILED DESCRIPTION - Detecting Salmonella typhimuriumbased on fluorescent probe of nitrogen-sulfur co-doped graphene quantum dots, involves preparing signal probe solution by using nitrogen-sulfur co-doped graphene quantum dots modified by aminated aptamer, where aminated aptamer comprises nucleotide sequence of 40 base pairs, which is 5'-NH2-(CH2)6-tatggcggcgtcacccgacggggacttgacattatgacag-3', and preparing magnetic separation probe solution by using streptavidin magnetic beads modified by biotinylated aptamer, where biotinylated aptamer comprises nucleotide sequence of 40 base pairs, which is 5'-Biotin-gaggaaagtctatagcagaggagatgtgtgaaccgagtaa-3', where the SEQ ID Nos are not defined. The X is the logarithmic value of Salmonella typhimuriumbacterial concentration colony forming unit/milliliter (cfu/mL) on the abscissa, Y is I0-I, the I0 is the fluorescence intensity at 423 nanometer (nm) when the blank control solution is detected, and the I in order to detect the fluorescence intensity at 423 nm of Salmonella typhimuriumsolution of 102, 103, 104, 105, 106, 107 cfu/mL. The test solution is prepared by taking 1 mL liquid milk, centrifuge at 8000×g for 5 minutes, discarding the supernatant, and resuspending the precipitate with 1 mL sterile phosphate-buffered saline (PBS) buffer with concentration of 0.1 molar (M) and pH 7.4 to obtain test solution. The 100 microliter (μL) signal probe solution and 36 μL magnetic separation probe solution is added to 500 μL of the solution to be tested, and incubated at 37℃ for 45 minutes to obtain composite solution. The composite solution is placed on magnetic stand for magnetic separation, and supernatant is taken to obtain solution to be tested. The solution to be tested is taken in a quartz cuvette, excitation wavelength of the Prism F97Pro fluorescence spectrophotometer is set to be 349 nm, and fluorescence intensity of the solution to be tested is measured at 423 nm. The I0-I value is substituted into the standard curve, and the Salmonella typhimuriumconcentration in the solution to be calculated is calculated, and the detection is completed, where I0is the fluorescence intensity at 423 nm when detecting the blank control solution, and I is to detect the solution to be tested. When the I0-I value is greater than 104, it indicates that Salmonella typhimuriumis detected in the test object, and indicates that no Salmonella typhimuriumis detected in the test object when the I0-I value is less than 104.