▎ 摘　　要

Carcinoembryonic antigen (CEA) is usually utilised as a reliable diagnostic and predictive marker of gastric cancer (GC). Herein, a target-responsive, label-free aptamer 'signal-on' fluorescent biosensing system was developed based on the synthesis of DNA-templated quantum dots via one-pot route and interactions with graphene oxide. CEA triggered aptamer-DNA hairpins hybridisation to release DNA to hybridise with DNA-CdTe QDs on GO and led to the fluorescence recovery of system with a 'signal-on' status. The fluorescence intensity was proportionate to CEA concentration, and highly sensitive sensing platform for detecting CEA was achieved with a wide linear range (5-250 ng/mL) and a low detection limit (1.17 ng/mL). This sensing strategy, the targeted detection of aptamer for CEA, provided a new direction in the detection of protein and construction of fluorescence biosensors.