Highly Sensitivive Detection For Carcinoembryonic Antigen Using Aptamer Based Sensors

Carcinoembryonic antigen?CEA?is a human glycoprotein involved in cell adhesion and expressed during human fetal development.As one of the common tumor markers,CEA is overexpressed in many human cancers,including gastric,colorectal,breast,ovarian,lung,and pancreatic cancer.And it has a great significance in differential diagnosis,therapeutic evaluation,and condition monitoring of cancers.Therefore,the development of highly sensitive CEA detection methods is of great significance for diagnosis and prognosis of diseases.Aptamers have been widely used in the field of sensors due to their flexibility,reproducibility,easy fixing,and regeneration.This work is mainly based on the principle of fluorescence resonance energy transfer?FRET?,using several different fluorescent materials?carbon dots,pyrene,copper nanoclusters,SYBR Green?,etc.?,aptamers,and graphene oxide?GO?,to achieve highly sensitive detection of CEA.1.Detection of carcinoembryonic antigen based on carbon dots?CDs?labeled aptamers and azide functionalized graphene oxide.CDs were covalently linked to the aptamers to make the aptamers with fluorescence.The fluorescent labeled aptamers and the azide functionalized graphene oxide?GO-N₃?performed a click reaction to form complex,and caused fluorescence to be quenched.After adding CEA,the CEA binding to aptamer could cause the conformation of aptamer to change,and the fluorescence was restored.2.Detection of carcinoembryonic antigen based on sandwich structure using carboxyl-functionalized graphene oxide and Ag@SiO₂.The sandwich structure could construct a detection platform with low background,thereby improving the detection sensitivity.At the same time,the addition of polyethylene glycol?PEG?could remove the non-specific adsorption on the surface of nanomaterials.In addition,we also applied the Ag@SiO₂ in the sensor to amplify the fluorescence detection signal.3.Detection of carcinoembryonic antigens based on copper nanoclusters?CuNCs?labeled aptamers combined with novel azide functionalized graphene oxide?GO-N₃?.This chapter used a new preparation method to synthesize azide functionalized graphene oxide.This method effectively removed the toxic effects on the human body during the preparation process and saved preparation time.The azide-functionalized graphene oxide?GO-N₃?could react with CuNCs-DNA with a click reaction.CEA could be detected by the change of fluorescence intensity before and after the addition of CEA.At the same time,this chapter used DNase I to digest the sensor to achieve the effect of amplifying the signal.4.Detection of carcinoembryonic antigen based on a fluorescent biosensor using magnetic graphene oxide and peptides.CEA was detected using magnetic graphene oxide?GO-Fe₃O₄?to quench SYBR Green?stained aptamers.At the same time,we introduced peptides on the surface of GO-Fe₃O₄.Peptides could resist the non-specific adsorption of charged proteins on the biosensor interface and improve the sensitivity of detection.In summary,four kinds of fluorescent biosensors have been constructed based on the principle of fluorescence energy resonance transfer using a variety of nanomaterials and fluorescent materials to achieve effective detection of CEA with good selectivity.The development of CEA detection methods and technologies can be helpful for the early detection and prevention of diseases which provide support and assistance for human health.