Graphene Composites Are Used For Electrochemical Immunoassay Of Dual Tumor Markers

Cancers are one of the major diseases that threaten human health. Tumor markers are molecules that occur in blood and tissues that are associated with cancer, and whose indification and determination is useful in patient diagnosis and clinical therapy. In clinical analysis, most methods for tumor markers determination are forced on one tumor maker determination, which often limit the diagnostic value. To address this, simultaneous determination of two or more tumor markers have simulated intense research recently. In this work, graphene nanocomposites are prepared to construct two kinds of electrochemical immunosensors for two tumor markers detection. The results in this work are listed as follows:1. Triple signal amplification using gold nanoparticles, bienzyme and platinum nanoparticles functionalized grapheme as enhancers for simultaneous detecting of CEA and AFPHere we demonstrated an ultrasensitive electrochemical immunoassay employing graphene, platinum nanoparticles (PtNPs), glucose oxidase (GOD) and horseradish peroxidase (HRP) as enhancers to simultaneously detect carcinoembryonic antigen (CEA) and alpha-fetoprotein (AFP). This immunosensor is based on the observation that multiple-labeled antibodies (thionine-labeled anti-CEA and ferrocene-labeled anti-AFP) recognition event yielded a distinct voltammetric peak through "sandwich" immunoreaction, whose position and size reflected the identity and level of the corresponding antigen. Greatly enhanced sensitivity for cancer markers is based on a triple signal amplification strategy. Experimental results revealed that the immunoassay enabled simultaneous determination of CEA and AFP in a single run with wide working ranges of0.01-100ng mL-1. The detection limits reached1.64pg mL-1for CEA and1.33pg mL-1for AFP. In addition, through the analysis of clinical serum samples, the proposed method received a good correlation with ELISA as a reference.2. A label-free immunosensor based on grapheme nanocomposites for simultaneous multiplexed electrochemical determination of CEA and AFPHere we prepared a label-free electrochemical immunosensor employing Indium tin oxide (ITO) sheets as working electrodes and graphene nanocomposites as supporting matrix for simultaneous determination of CEA and AFP. Reduced graphene oxide/thionine/gold nanoparticles nanocomposites were synthesized and coated on ITO for the immobilization of anti-CEA while reduced graphene oxide/Prussian Blue/gold nanoparticles were used to immobilize anti-AFP. The immunosensor determination was based on the fact that due to the formation of antibody-antigen immunocomplex, the decreased response currents of thionine and Prussian Blue were directly proportional to the concentrations of corresponding antigens. Experimental results revealed that the multiplexed immunoassay enabled the simultaneous determination of CEA and AFP with linear working ranges of0.01-300ng mL-1. The limit of detections for CEA is0.650pg mL"1and for AFP is0.885pg mL-1. In addition, the methodology was evaluated for the analysis of clinical serum samples and received a good correlation with ELISA.