Construction Of Functional Graphene Electrochemical Aptamer Sensor And Detection Of Tumor Markers

Cancer,which generally refers to malignant tumors,is one of the major diseases that endanger human life and health,and most of them can be prevented and treated.It is generally believed in the medical community that early screening can greatly reduce cancer mortality.Tumor markers,as a class of important chemicals that reflect the presence of tumors,play a major role in the differential diagnosis,prognosis,and treatment evaluation of cancer.However,the content of tumor markers in primary cancer patients is extremely low.How to detect tumor biomarkers quickly,sensitively and accurately has always been an important research topic in the field of biosensing.Electrochemical aptamer sensor is an ideal tool for rapid,accurate,sensitive,and specific detection of tumor markers in samples,which combine the advantages of both aptamer and electrochemical analysis.Electrochemical signal amplification can effectively enhance the sensitivity of target detection,which is also a key issue in constructing high-performance electrochemical aptamer sensors for tumor markers.Therefore,based on the electrochemical signal amplification strategy of nanomaterials,this article uses functional fossil graphene nanocomposites to construct two types of electrochemical aptamer sensors,namely,ratiometric and labeled,to achieve the quantitative detection of two tumor markers,carbohydrate antigen 19-9（CA19-9）and mucin 1（MUC1）.The main research content in this article is:（1）A study on the detection of CA19-9 using a ratio type electrochemical aptamer sensor modified with AuNPs/rGO-MWCNTsSelf assembled AuNPs/rGO-MWCNTs nanocomposites on the surface of a glassy carbon electrode,covalently linked to anthraquinone-2-carboxylic acid labeled aptamer complementary DNA（AQ-c DNA）via Au-S,and bound to a ferrocene（Fc）labeled aptamer（Fc-Apt）through base pairing to construct a sensing interface with specific recognition targets and electrochemical signal amplification.The ratio of the response signal to the reference signal(I_Fc/I_AQ)in the text serves as the target molecule response signal.This ratio strategy can effectively eliminate the interference of external factors on the sensor is enhanced the performance of the sensor in detecting target molecules.Under the optimal reaction conditions,the logarithm of CA19-9 concentration has a good linear relationship with I_Fc/I_AQ,with a linear range of 1.0～1.0×10⁶ m U/m L,with a detection limit of 0.65 m U/m L.This ratio based electrochemical biosensor based on aptamer molecular recognition has advantages of good selectivity,reproducibility,and stability.（2）A study on the detection of MUC1 using AuNPs/PPy/rGO modified labeled electrochemical aptamer sensorsThe AuNPs/PPy/rGO nanocomposites obtained by the simultaneous reduction of chloroauric acid and GO in the PPy/GO system by sodium borohydride were immobilized on the surface of the glassy carbon electrode.MUC1 aptamer linked by Au-S covalent bond could be bind to AuNPs and thionine labeled aptamer complementary DNA（CP-Au-Thi）.In the presence of MUC1,the sensor surface adapter can combine with it,causing CP-Au-Ti to detach from the electrode surface,and the sensor causes an electrical signal.Under optimal conditions,the logarithm of MUC1 concentration and peak current variation value（ΔI）Has a good linear relationship with a linear range of 1.0×10^-6～10 ng/m L,with a detection limit of0.5 fg/m L.Effectiveness of the labeled electrochemical aptamer sensor has been verified in human serum reagent samples,with recoveries ranging from 94.24%to 105.26%.Research on functional fossil graphene electrochemical aptamer sensors carried out in this paper provides an effective method for the rapid and accurate detection of CA19-9,MUC1,and other tumor markers.The research results have great significance in the field of biological detection.