Study On Electrochemical Biosensor Based On Spatial Conformational Change Of Hairpin Structure DNA

It is important for the detection of specific DNA sequences in diagnosis of diseases,so it is necessary for the establishment of detection method for DNA with high sensitivity,good specificity.At present,electrochemical method has been paid much attention due to its simplicity,cheapness and high sensitivity.In these electrochemical methods,hairpin structure DNA was widely used due to its excellent specificity.In this thesis,we proposed a new electrochemical sensing method for target DNA based on the spatial conformational change of hairpin structure DNA and electrochemical activity of rutin.1.In the first chapter,it was introduced for the principle and classification of DNA sensor,DNA electrochemical biosensor and hairpin DNA electrochemical biosensor.The method of three kinds of sensor for the detection of specific sequences of DNA and the application in their fields were described respectively;the application of gold nanoparticles modified on sensor was introduced;finally the purpose and avenue of this paper was described.2.In second chapter,we developed an electrochemical biosensor with good performance based on the hairpin DNA,and the biosensor was achieved to detect the b3a2 gene of chronic myeloid leukemia.In this work,the gold nanoparticles and hairpin DNA were modified on the electrode surface firstly,and then,the hairpin DNA was combined with target DNA on the electrode surface.Later,the modified electrode was put in the rutin solution,and the rutin was modified on the above electrode through electrochemical method.Finally,the electrochemical signal of rutin of the modified electrode was studied.The experiment results showed that the electrochemical current of the rutin increased obviously after the electrode hybrided with target DNA.The increase of the current of rutin may be based on spatial conformational change of the hairpin DNA on the electrode surface before and after the hybridization with target DNA,which resulted in the increase of the quantity of rutin that modified on the electrode surface.Accordingly,the obtained biosensor was used for the detection of specific target DNA sequences successfully,and the constructed biosensor showed good ability of specific recognition.3.In the third chapter,the feasibility of the biosensor that based on the second chapter was further verified through the application of this sensing method for the detection of Legionella pneumophila.The experimental results showed that the new method had certain feasibility and can be used to construct different biosensor to detect different kinds of target DNA sequence,which broadened the idea for the development of hairpin DNA based electrochemical biosensor.4.In the fourth chapter,the electrochemical behaviour of the rutin was investigated in the presence of rhodamine B,protoporphyrin or fluorescein,respectively.Furthermore,UV spectrometry and fluorescence spectrometry were used to study the interaction between rutin and rhodamine B,protoporphyrin or fluorescein.This study is of great significance for electrochemical biosensor that based on the hairpin DNA and electrochemical activity of rutin.