Hairpin Assembly Amplified Electrochemical Biosensor For Highly Sensitive And Specific Detection Of DNA

DNA(deoxyribonucleic acid)is a genetic information carrier of organisms.Recent studies have shown that abnormal expression of DNA closely related to the occurrence,development and prognosis of many diseases.The traditional methods of DNA detection have some limits,such as complex operation,high cost,and long-time consuming.Therefore,it is of great significance to develop a simple,sensitive and specific new method for DNA quantitative detection.In this study,a simple electrochemical biosensing technique was established for highly sensitive and highly specific detection of DNA by integrating the hairpin assembly amplification reaction(HAA)and enzyme-catalyzed signal amplification.The target DNA could hybridize with the biotin-labeled hairpin H1 through complementary sequences and unfold the hairpin structure of H1.Then,the hairpin H2 hybridized with the opened hairpin H1 and displaced the target DNA,generating H1-H2 complex.The displaced target DNA could trigger the next cycle of hairpin assembly circuit and the formation of numerousH1-H2 complexes.Subsequently,the H1-H2 complex hybridized with the capture probe immobilized on the electrode.The biotin in the capture probe-H1-H2 complex bond to streptavidin alkaline phosphatase(ST-ALP)and catalyzed the substrate a-naphthol(a-NP)to produce electrochemical signal.Mismatched base sequences were set at the breath site to decrease the non-specific hybridization reaction between hairpins,which reducing the background signals.Under optimal conditions,the average current response showed excellent correlation with the logarithmic concentration of target DNA in the range from 25 p M to 25 n M,with a correlation coefficient of 0.9974.And the detection limit of this approach for target DNA was calculated to be 20 p M,and showed high selectivity toward single-base mismatch.In this report,a new strategy based on mismatched hairpin assembly amplification and enzyme catalysis signal amplification was firstly proposed for high sensitive and specific detection of DNA,which had the potential value in early diagnosis of diseases based on DNA detection.