▎ 摘　　要

A simple label-free amperometric immunosensor for protein detection is developed based on TiO2-graphene (TiO2-Gr), chitosan and gold nanoparticles (AuNPs) composite film modified glassy carbon electrode (GCE). The negatively charged AuNPs can be adsorbed on the positively charged chitosan/TiO2-Gr composite film by electrostatic adsorption, and then is used to immobilize alpha-fetoprotein antibody for the assay of alpha-fetoprotein (AFP). The interaction of antigen and antibody on the electrode interface makes a barrier for electrons and inhibits the electro-transfer, resulting in the decreased DPV signals of probe Fe(CN)(6)(3-/4-). Using this strategy, a wide detection range (0.1-300 ng mL(-1)) with the correlation coefficients of 0.992-0.994 for model target AFP is obtained. The limit of detection is 0.03 ng mL(-1) at a signal-to-noise ratio of 3. The results prove that the sensing strategy possesses sensitivity, selectivity, stability and generality, and it may be used to immobilize other biomoleculars to develop biosensor for the detection of other antigens or biocompounds. (c) 2012 Elsevier B.V. All rights reserved.