Method for detecting circulating tumor nucleic acid based on functionalized black phosphorus biosensor

[0046] Example 1: Preparation of p-nitrobenzene functionalized black phosphorus biosensor

[0047] Disperse 1 mg of black phosphorus (which can be black phosphorus nanosheets, black phosphorus quantum dots or black phosphorus micro-nanoparticles) in 1 mL of acetonitrile solution to obtain a black phosphorus suspension, then add 5 mg of p-nitrobenzene tetrafluoroborate diazonium salt, After mixing, stir in the dark for 20 hours, centrifuge at 12,000 rpm for 10 minutes, wash the precipitate twice with ethanol and twice with water to obtain a p-nitrobenzene functionalized black phosphorus biosensor.

[0048] Example 2: Fluorescence Quenching Effect of p-Nitrobenzene Functionalized Black Phosphorus on DNA Probes

[0049] Prepare the corresponding single-stranded DNA probe solution as required, such as 30 μL 500nmol / L 6-carboxyfluorescein (FAM) labeled single-stranded DNA probe, and analyze the fluorescent signal of the solution with fluorescence, such as figure 1 In the blank control curve; then add an equal amount of black phosphorus and p-nitrobenzene functionalized black phosphorus (embodiment 1) respectively in the probe solution of the same volume and concentration, and detect fluorescence on a fluorometer, and observe the fluorescence signal Case.

[0050] Test results such as figure 1 shown, from figure 1 It can be seen from the figure that compared with the blank control group, the fluorescence signal of the p-nitrobenzene functionalized black phosphorus group became very weak, and 95.5% of the fluorescence signal could be quenched, while the black phosphorus group on

[0051] Example 3 A Method for Detecting Circulating Tumor Nucleic Acids Based on Functionalized Black Phosphorus Biosensor

[0052] Method: Mix 30 μL of 500nmol / L 6-carboxyfluorescein (FAM)-labeled single-stranded DNA probe (the probe can reversely pair with the target ctDNA) solution and the sample solution to be tested. After hybridization for 15 minutes, add 30 μL 100μg / mL p-nitrobenzene functionalized black phosphorus was reacted at room temperature for 15 minutes, the fluorescence curve was measured, and the change of fluorescence before and after adding p-nitrobenzene functionalized black phosphorus was compared. The excitation wavelength was 488nm.

[0053] Analysis of the results: If the fluorescence intensity does not change significantly before and after adding p-nitrobenzene-functionalized black phosphorus, then there is no target ctDNA combined with the fluorescent probe in the sample to be tested; if p-nitrobenzene-functionalized black phosphorus is added, If the