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Biosensing detection system for detecting ctDNA and detection method thereof

A detection system and biosensing technology, applied in biochemical equipment and methods, microbial determination/inspection, etc., can solve the problems of inability to detect clinical low-abundance samples, low sensitivity, poor stability, etc., and achieve excellent resistance to nucleic acids. Enzymatic cleavage, improved sensitivity and improved stability

Pending Publication Date: 2022-04-29
HUNAN UNIV
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  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0005] However, the CRISPR / Cas12a system also has two significant disadvantages
On the one hand, the stability is poor, because the trans-cleavage substrate of Cas12a is generally ssDNA, but the stability of ssDNA in complex physiological environments such as serum is poor, and it is easily degraded by nucleases, resulting in false positive signals
On the other hand, the pure CRISPR / Cas12a system has low sensitivity and cannot be used for the detection of clinical low-abundance samples

Method used

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  • Biosensing detection system for detecting ctDNA and detection method thereof
  • Biosensing detection system for detecting ctDNA and detection method thereof
  • Biosensing detection system for detecting ctDNA and detection method thereof

Examples

Experimental program
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Effect test

Embodiment 1

[0026] Example 1 - Biosensor Sensitivity Analysis

[0027] Detection method flow chart of the present invention, as figure 1 As shown, the specific steps are as follows:

specific Embodiment approach

[0028] This embodiment provides a specific implementation of a biosensor based on ctDNA highly sensitive and specific detection, specifically the following steps:

[0029] S1. Preparation of 13nm gold nanoparticles: first soak the round bottom flask with aqua regia, and then thoroughly clean it with ultrapure water. Add 100mL of 0.01wt% chloroauric acid solution to a clean round bottom flask, then put the round bottom flask into an oil bath, set the oil bath temperature to 130°C, and the rotation speed to 800rpm. After the solution boils, continue to boil for 10 minutes to remove the dissolved oxygen in the solution. Increase the rotation speed to 1200rpm, then quickly add 1mL of 3wt% sodium citrate to the solution, the solution changes from light yellow to dark gray, then purple red, and finally wine red, and continue to boil after the color remains unchanged 30min. After the solution was naturally cooled to room temperature, it was stored at 4° C. in the dark, and the averag...

Embodiment 2

[0037] The difference between the steps of this example and Example 1 lies in the rolling circle amplification reaction stage. In this example, 2 μL of 100 nM 5’ phosphorylated linear padlock probe, 2 μL of different types of ctDNA (PIK3CAE542KM, mismatch-PIK3CAE542KM, KRAS G12DM) and 0.3 μL of T4 ligase (1000 U / μL) were mixed in 1×T4 Incubate at 20°C for 20 minutes in ligase reaction buffer, and then heat-treat at 65°C for 5 minutes to inactivate T4 ligase, and finally obtain a circular DNA template. In the amplification reaction, add 8 μL dNTP (2.5 mM), 0.8 μL BSA (20 mg / mL), 0.4 μL phi29 enzyme (10 U / μL) and 4 uL phi29 buffer to the above reaction solution, incubate at 30°C for 30 minutes, and heat at 65°C for 10 minutes. Finally, the long ssDNA product, namely the RCA product, was obtained.

[0038] The selective analysis results of the biosensing detection system are as follows: image 3 As shown, the RCA-CRISPR / Cas12a system only has a significant fluorescence response...

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Abstract

The invention discloses a biosensing detection system for detecting ctDNA and a detection method thereof. The biosensing detection system comprises a spherical nucleic acid reporter, an RCA product and a CRISPR / Cas12a system, wherein the spherical nucleic acid reporter is a gold nanoparticle modified by a sulfydryl DNA chain; the RCA product is a product obtained by carrying out RCA amplification reaction on the ctDNA of the object to be detected and the 5 '-phosphorylated linear padlock probe; the CRISPR / Cas12a system comprises a stable binary complex formed by the LbCas12a protein and the crRNA (Complementary Ribonucleic Acid). The SNA provided by the invention has excellent nuclease cutting resistance in a physiological environment. Therefore, the SNA reporter is used for replacing the ssDNA reporter, so that the stability of the CRISPR / Cas12a system can be improved; rolling circle amplification (RCA) has the advantages of simplicity in operation, mild reaction temperature, high amplification efficiency and the like, and the RCA is combined with a CRISPR / Cas12a system, so that the sensitivity of the system can be remarkably improved.

Description

technical field [0001] The invention belongs to the technical field of biological detection, and in particular relates to a biosensing detection system and a detection method for detecting ctDNA. Background technique [0002] Circulating tumor DNA (ctDNA) is released into the peripheral blood circulation system by primary tumor tissue, circulating tumor cells and other micrometastases through apoptosis, necrosis, and direct secretion, and is highly related to cancer. Circulating tumor DNA testing is a non-invasive liquid biopsy technique. Compared with traditional invasive tissue biopsy techniques, liquid biopsy can better reveal the heterogeneity of tumors in space and time; provide a more comprehensive disease description; and can detect drug efficacy and drug resistance in real time. Moreover, the half-life of circulating tumor DNA is very short, generally only 15 minutes to two hours, so it can more accurately reflect the current status of the tumor than traditional pro...

Claims

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Application Information

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IPC IPC(8): C12Q1/6886C12Q1/6844
CPCC12Q1/6886C12Q1/6844C12Q2521/327C12Q2531/125C12Q2563/107C12Q2563/137C12Q2563/155C12Q2565/607
Inventor 陈美柯国梁周敏殷垚张晓兵
Owner HUNAN UNIV