Construction And Application Of Electrochemical DNA Biosensing Platform

With the rapid development of modern medicine,more and more studies show that biomolecules play very important roles in the regulation of physiological functions,the diagnosis of related diseases and the expression of genetic information.Some subtle changes of biomolecules expression in the human body can cause serious biomedical and biological effects,such as disease,drug resistance,and even genetic expression errors.Studies have also shown that some specific biomolecules are used as biomarkers for monitoring the occurrence and development of diseases.Therefore,it is very urgent to construct a rapid and efficient detection strategy to sensitively detect specific biomarkers.At present,there are quite a few detection methods to detect specific biomolecules,such as fluorescence,surface enhanced Raman spectroscopy,colorimetry,electrochemistry,etc.Among them,the electrochemical detection method has the advantages of high sensitivity,low cost,high specificity and portability compared with other detection methods.Herein,we take the advantages of electrochemistry and the characteristics of DNA configuration to build an electrochemical biosensing platform.There is better electrochemical performance for biomolecules detection when adjusting the surface density and spatial arrangement of probe DNA on the sensing interface.In addition,multiple signal amplification strategies are introduced to further improve the analytical performance of the electrochemical biosensing platform and achieve ultrahigh sensitivity for biomolecules analysis.The contents of this thesis are as follows:1.An electrochemical biosensor platform was constructed based on DNA hairpin structure.The stem-loop structure of probe DNA was assembled onto gold electrode surface by Au-S bond.The performance of adenosine triphosphate aptamer(ATPA)and adenosine triphosphate(ATP)at the biosensor interface was detected by adjusting the surface density of the stem-loop structure DNA on the electrode surface.Furthermore,and the contribution of co-existed hairpin DNA and double-stranded DNA(ds DNA)was explored on the total current intensity.The experimental results show that the sensing platform can detect the concentration of ATPA and ATP as low as 0.74 f M and5.04 p M,respectively,when the surface density of hairpin DNA probe is moderate(5.72pmol/cm~2).Moreover,the sensing platform has high selectivity and good regeneration.When ATPA at 10 p M,the formed ds DNA contributed 31.87%in the total electrochemical signal.Based on the above results,we designed an XOR logic gate for simultaneous detection of ATPA and ATP.2.An electrochemical biosensor platform was constructed based on multiple signal amplification system.On the basis of results above,we introduce a multiple signal amplification strategy to ultrasensitively detect target micro RNA-21(mi RNA-21).After optimizing the electrochemical detection performance,the triple amplification electrochemical sensing platform was constructed by toehold-mediated strand displacement reaction(TSDR),hybrid chain reaction(HCR)and enzyme-assisted amplification,showing an ultrawide detection range(1 a M-10 n M),an ultralow detection limit(1.03 a M)and good selectivity.In addition,the designed sensing platform can also detect mi RNA-21 in 10 He La cells.All results suggest that this electrochemical biosensor platform has excellent potential application prospects in biochemical analysis,early detection of diseases and other fields.