A reagentless amperometric immunosensor for α-1-fetoprotein based on gold nanowires and ZnO nanorods modified electrode

A novel strategy for the preparation of reagentless immunosensor for rapid determination of a-l-fetoprotein (AFP) in human serum has been developed. The immunosensor was prepared by immobilizing alpha-1-fetoprotein antibody (AFP Ab) onto the glassy carbon electrode modified by gold nanowires (Au NWs) and ZnO nanorods (ZnO NRs) composite film. Gold nanowires and ZnO nanorods were produced by an electrodeposition strategy using nanopore polycarbonate (PC) membrane. A sandwich immunoassay format was employed to detect AFP with horseradish peroxidase (HRP)-labeled AFP as tracer. The morphology of the Au NWs and ZnO NRs composite film has been investigated by scanning electron microscopy (SEM) and energy disperse spectroscopy (EDS) analysis. The resulting immunosensor offered an excellent amperometric response for AFP ranging from 0.5 to 160.0 ng mL(-1) with a detection limit of 0.1 ng mL(-1). Because of the combination of the biocompatibility of ZnO NRs and the direct electron-transfer of Au NWs between HRP and electrode, the proposed immunosensor displayed a direct electrochemical response of HRP to the reduction of H2O2 with high sensitivity, quick response, good repeatability and long-term stability. (C) 2008 Elsevier B.V. All rights reserved.