Assay Of Tumor Biomarkers By Electrochemical Method Based On DNA Hairpin Structure

Tumor,which seriously endangers human lives and health,now is one of the major malignant diseases with high morbidity and mortality all over the world.At present,for tumor patients,the key of improving survival rate and prognosis are early detection and early treatment.Therefore,early diagnosis for tumor is of great necessity in clinical research.Detection of tumor biomarker is one of the methods for tumor early diagnosis.However,the existing tumor biomarker detection methods have some disadvantages of complicated,time-consuming and low sensitive.As a result,it is highly required to develop new tumor biomarker detection methods for assay of important tumor biomarkers with high sensitivity and high specificity,in order to improve the efficiency and accuracy of tumor diagnosis.Electrochemical biosensor possesses the advantages of high sensitivity,time saving,convenience and economy.In this paper,based on DNA hairpin structure,a new-type electrochemical biosensor,and a sensitive,specific and efficient platform for tumor marker detections were achieved.1.A novel method to detect AML biomarker Siglec-5In this work,based on DNA hairpin structure and aptamer,we constructed a new-type electrochemical biosensor for detecting AML biomarker Siglec-5.Specifically,a thiol group is modified on the 5'-terminal of the probe sequence and MB moiety is modified on its 3'-terminal.Thus,the hairpin structured DNA can be immobilized on the gold electrode through the Au-S bond.At this point,a relatively large electrical signal of MB can be detected as the modified MB on the hairpin-structured DNA is close to the surface of the gold electrode.In the process of experiment,the change of hairpin structure leads to the change of signal intensity.Finally,signal output was attained through an electrochemical workstation,so we can realize to detect Siglec-5.This method will provide new ideas for the diagnosis of tumor markers in future clinical diagnosis.2.A novel method to simultaneously detect two HCC biomakersIn this work,based on the above work,we have designed a dual-functional hairpin DNA sequence,which consists miR-16 complementary sequence and AFP aptamers,as the electrochemical sensing probe(ESP)for one-step and simultaneous determination of miR-16 and AFP.In the meantime,by coupling methylene blue(MB)with silver nanoparticles(AgNPs),non-interfering electrochemical signals can be detected that are corresponding to miR-16 and AFP,respectively.Moreover,since MB and AgNPs have shown excellent electrochemical response,the sensitivity of this assay can also be guaranteed.As a result,simplicity and sensitivity of the assay has been achieved in this ingenious design to monitor both miRNA and protein biomarkers.So,this strategy may have promising application in HCC diagnosis in the future.