▎ 摘　　要

NOVELTY - Preparing nanocomposite-based biosensor comprises: adding ultrapure water into the graphene oxide (GO)-iron oxide nanocomposite material following by ultrasonically dissolving; obtaining the deposition solution by adding 3,4-ethylenedioxythiophene (EDOT) and continuous ultrasonically dissolving; depositing the deposition solution by cyclic voltammetry to obtain GO-iron oxide/poly 3,4-ethylenedioxythiophene (PEDOT) nanocomposite; and mixing the catalyst and the aminated DNA to prepare an incubation solution, and dripping it on the GO-iron oxide/PEDOT nanocomposite material to obtain the biosensor based on the GO-iron oxide/PEDOT nanocomposite material. USE - The method is useful for preparing nanocomposite-based biosensor, preferably GO-iron oxide/PEDOT nanocomposite-based biosensor, which is useful in dual-mode detection of microRNA (all claimed). ADVANTAGE - The method: utilizes two detection modes of chronocoulometry and current-time (I-T) techniques, which have better selectivity and higher sensitivity, and can meet the precise requirement for detecting the microRNA in current serum; provides an important support for developing a rapid on-line detection device for detecting microRNA expression level in serum; can synthesize the GO-iron oxide/PEDOT nanocomposite material of the biosensor substrate, which has good conductivity and large specific surface area; can realize rapid detection, on-site detection and mutual confirmation, when compared with the traditional detection methods; and provides biosensor with good stability. DETAILED DESCRIPTION - INDEPENDENT CLAIMS are also included for: a GO-iron oxide/PEDOT nanocomposite-based biosensor obtained by the preparation method; and an application of a GO-iron oxide/PEDOT nanocomposite-based biosensor in dual-mode detection of microRNA.