Preparation method and applications of aptamer electrochemical sensor for detecting malachite green (MG)

The invention provides an aptamer electrochemical sensor for detecting malachite green (MG). A preparation method for the electrochemical sensor comprises the steps of: the prepared graphene-chitosan compound and nanogold are modified on an electrode surface, an aptamer is connected on the nanogold through chemical action, a target object is bound onto the electrode surface through the specific binding action of the aptamer and the target and then connected with an antibody of the target object, thus constructing the biosensor with a sandwich structure. When the detected solution contains the target object, a certain amount of target objects and corresponding antibodies can be fixed on the electrode surface, so that a sensing structure is formed. Horseradish peroxidase (HRP) is modified on the antibodies, and the hydrogen peroxide can be catalyzed to be decomposed, so that the change of an electrochemical signal can be generated, and the detection on the MG can be realized through the change of the electrochemical signal. The prepared aptamer electrochemical sensor is strong in selectivity, high in sensitivity, simple and fast to operate, and suitable for detection on the MG of aquatic products.