Graphene-based dual-mode electrochemical-FET aptasensor for rapid zeptomolar detection of CEA

An electrochemical (EC) sensor has been developed integrated with a field effect transistor (FET) based on reduced graphene oxide (rGO) for ultrasensitive, rapid, and selective detection of carcinoembryonic antigen (CEA) over a wide dynamic range of up to eight orders of magnitude. An aptamer receptor was immobilized on the rGO surface, which had an initial hole mobility of 7 cm²/(V·s). Cyclic voltammetry and transfer curves measurements were used to monitor the biosensor assembly and to detect the CEA biomarker. This dual-mode aptasensor provides both high sensitivity across a wide dynamic range and the capability for mutual verification. The FET biosensor has a limit of detection as low as 60 ag/mL (0.33 zM), with a response time of 2 min. The overall dynamic range of the EC-FET aptasensor covers concentrations from 0.1 fg/mL to 10 ng/mL, with the FET mode spanning from 0.1 fg/mL to 10 fg/mL and for EC mode spanning from 1 fg/mL to 10 ng/mL. Thus, we have developed the scalable, low-cost method for fabricating a highly sensitive, label-free aptasensor with an improved dynamic range for CEA detection.