Detection Of Bt Gene By Triple-helical Molecular Beacons Of Fluorescently Modified Double-stranded DNA-Coupled Single-stranded DNA

In today's world,the development of science and technology is changing with each passing day,and the advancement of science and technology has led to the development of modern biotechnology.Genetically modified technologies is also called the second"green revolution"in the history of mankind with rapid progress.Genetically modified technologies is to introduce foreign genes on the basis of the original genes of crops,transform their genetic material,and make their nutritional value and biological traits better meet human needs.The transgenic technology was used to transfer Bacillus thuringiensis Bt into wheat,mainly to increased the insect resistance of wheat.The delta-endotoxin gene of Bacillus thuringiensis is the most important reason for wheat to oBtain insect resistance.However,there are certain biosafety problems in genetically modified technologies,so countries around the world continue to strengthen the supervision and testing of genetically modified crops.In this paper,single-stranded DNA(TFO)labeled with fluorescent quenching group(BHQ-1)and single-stranded DNA(Single DNA S-DNA)with both fluorescent groups(FAM-6)ware constructed,the triple helix DNA molecular beacon was then contacted by the target DNA single strand(Target DNA T-DNA)and the triple helix DNA molecular beacon,resulting in a change in the triple helix structure,and also resulting in a change in the intensity of the fluorescent signal,enabling sensitive detection of the transgenic crop.The main contents are as follows:Self-assembled triple helix molecular beacons ware used for sensitive detection of target gene Bacillus thuringiensis Bt in transgenic crops in weakly acidic environments;in recent years,triple helix molecular beacons had been widely used in genetically modified crops.Sensitive detection,included T·A.T and C~+·G?C(?Watson-Crick hydrogen bonds,·Hoogsteen hydrogen bonds)and other three-helical structures ware the most commonly used.When triple helix molecular beacons ware formed,triplex-forming oligonucleotides(TFOs)containing pyrimidine chains(thymine T and cytosine C)needed to be protonated first in a weakly acidic pH environment and double-stranded DNA.The chain(A and G)combine to formed a stable triple helix molecular beacon,in which the cytosine C-containing DNA single strand(TFO)protonated,the positively charged cytosine C~+and the negatively charged DNA double strand due to electrostatic The function could stabilize the triple helix molecular beacon.In this way,the addition of the target DNA single strand could destroy the structure of the triple helix beacon and led to the change of fluorescence intensity,and achieve sensitive detection of the transgenic crop with a limit of detection of 1 pM.Self-assembled triple helix molecular beacons for sensitive detection of transgenic crop target gene Bacillus thuringiensis Bt in neutral environment;in order to expand the application range of triple helix molecular beacons,in this paper Artificial addition of Ag~+was used to increase the stability of the triple helix molecular beacon in a neutral environment.Ag~+could specifically recognizes C·G.C's triple helix structure.The H~+substitution in C formed Ag~+C·G.C new triple helix structure,so the addition of Ag~+greatly increased the application range of triple helix molecular beacons.The addition of the target DNA single strand could destroy the structure of the triple helix beacon and lead to a change in fluorescence intensity,enabling sensitive detection of the transgenic crop,and achieve sensitive detection of the transgenic crop with a limit of detection of 0.1 pM.