Multifunctional Gene Detection Platform Based On Strand Displacement Reaction

DNA is the most important genetic material in the body.Due to its natural advantages in information storage,biocompatibility,structural diversity,and design flexibility,DNA is widely used in the construction of biosensors,molecular logic gates,molecular imaging,and molecular motors.DNA biosensors have the advantages of wide response range,diverse structural changes,and the like,enabling sensitive detection of various metal ions and biomolecules such as ATP,protein,miRNA,and DNA.Nucleic acid can also be used as an important biomarker for biological research and medical diagnosis.Various disasters in the human body such as pancreatic cancer,lung cancer,trisomy 21 syndrome,and the like are all associated with genetic material mutations.Nucleic acid sequence analysis and detection is an important way to achieve individualized medical treatment,effective diagnosis and management of cancer and infectious diseases.In recent years,DNA biosensors have been widely applied in the field of gene detection.The paper is mainly divided into the following three parts:The first chapter mainly introduces the basic principles of the toehold-mediated strand displacement reaction and the target-induced strand displacement reaction,and its application in DNA molecular devices,various functional nucleic acid molecules and their applications,and the fluorescence characteristics of 2-aminopurine probes.In the second chapter,the label-free entropy-driven DNA cycle was constructed using NMM as a probe,and it was applied to the detection of target DNA.D1 bound to the toehold region in HP and underwent a strand displacement reaction,exposing the toehold region that can hybridize with the fuel chain and trigger the following strand displacement reaction.The fuel chain hybridized with HP to form a stable double strand.As a result,D1 and the tethered PW17 sequence were released.The D1 strand can be re-involved in the next cycle and PW17 formd a G-quadruplex structure.NMM bound to K+-stabilized G-quadruplexes,and the fluorescence intensity of the system increases significantly.The detection limit for the target gene is up to 1 nM.In the third chapter,we use 2-aminopurine as a probe to achieve sensitive detection of two pancreatic cancer-related genes.The target-induced strand displacement reaction triggered by ATP and potassium ions exposed the originally blocked toehold region.The addition of P53 gene and K-ras gene bound to the toehold region and trigger the toehold mediated DNA strand displacement reaction.As a result,the signal probe was totally released and formed a hairpin with a looped-out 2-AP in the stem,accompanying with a significant increase of fluorescence intensity.The limit of detection of target genes is 2nM with a wide linearity range and excellent regression coefficient.