▎ 摘　　要

Graphene-based thin film has been widely used as signal conductor and platform material in electrochemical sensors. For commonly used reduced graphene oxide (rGO), oxygen-containing functional groups can provide coupling sites to conjugate with bio-cognitive elements, but high degree of oxidation can harm its structural integrity and signal conductivity. In this work, a new strategy is developed to balance the conductivity and functionality of rGO. The PTCA-rGO composite film was prepared by self-assembly and used to fabricate electrochemical biosensor. To form reusable thrombin aptasensor, an in situ layer-by-layer self-assembling method was adopted to stepwise deposit reduced graphene oxide (rGO), 3, 4, 9, 10-perylenetetracarboxylic acid (PTCA), and thrombin aptamer (TBA) onto 3-aminopropyltriethoxy silane (APTES)-modified glassy carbon electrode (GCE). The as-prepared aptasensor was used to determine thrombin in response to impedimetric signal by electrochemical impedance spectroscopy (EIS). The as-prepared GCE/rGO/PTCA/TBA sensor provided outstanding performance for determination of thrombin concentration with wide linear range (1 pM-100 nM), low detection limit (0.2 pM), reusability, and good specificity to thrombin. The good performance of GCE/rGO/ PTCA/TBA aptasensor can be attributed to the electrochemical property of rGO-PTCA composite film and the in situ layer-by-layer fabricated strategy. This PTCA-modification method is promising to be widely used in the fabrication of graphene-based electrochemical devices.