▎ 摘　　要

A signal-off aptasensor was described based on well-designed aptamer-Cu-3(PO4)(2) hybrid nanoflowers&graphene oxide composites (aptamer-Cu-3(PO4)(2)HNF&GO) as an effective sensing platform and molybdophosphate precipitation as the signaling element. The aptamer, as the biorecognition unit grafted on aptamer-Cu-3(PO4)(2)HNF&GO by the specificity of streptavidin and biotin, captured the carcinoembryonic antigen (CEA) through specific interaction. The molybdophosphate precipitation were formed by the reaction of the aptamer-Cu-3(PO4)(2)HNF&GO with molybdate (MoO42-). However, the CEA-aptamer bioconjugate layer films not only hinder electron transfer on the sensing interface, but also impede the formation of molybdophosphate precipitation, resulting that the current signal significantly decreased. So, a simple aptasensor for CEA was constructed with high sensitivity and signal-off model. Under optimal experimental conditions using square wave voltammetry (SWV), the response peak currents decreases linearly with the logarithm of CEA concentrations in the range from 10 fg mL(-1) to 500 ng mL(-1). Also, the feasibility of its applications has also been demonstrated in the analysis of clinical serum samples.