Capillary electrophoresis-chemiluminescence detection for carcino-embryonic antigen based on aptamer/graphene oxide...

A new strategy is proposed for determination of carcino-embryonic antigen (CEA) based on aptamer/graphene oxide (Apt/GO) by capillary electrophoresis-chemiluminescence (CE-CL) detection system. CEA aptamer conjugated with horseradish peroxidase (HRP) firstly mixes with GO, and the CL will be quenched because the stack of HRP-Apt on GO leads to chemiluminescence resonance energy transfer (CRET). When CEA exists, the specific combination of HRP-Apt and CEA can form HRP-Apt-CEA complex, which dissociates from GO. Then, the CL catalyzed by HRP-Apt-CEA complex can be detected without any CRET, and the content of CEA can be estimated by the CL intensity. It has been proved that the interference issue resulted from free HRP-Apt is solved well by mixing GO firstly with HRP-Apt, which blocks the free HRP-Apt's CL signal due to CL quenching effect of GO; and the interference resulted from GO to CL is also solved by CE, then the sensitivity and accuracy can be greatly improved. Results also showed that the CL intensity had a linear relationship with the concentration of CEA in the range from 0.0654 to 6.54 ng/mL, and the limit of detection was approximately 4.8 pg/mL (S/N = 3). This proposed method with high specificity offers a new way for separation and determination of biomolecule, and has good potential in application of biochemistry and bioanalysis.