▎ 摘　　要

Titania nanosheet modified reduced graphene oxide (TiO2NS-rGO) nanocomposites have been synthesized and then used to immobilize hemoglobin (Hb) to fabricate a mediator-free biosensor. The morphology and structure of the TiO2NS-rGO nanocomposite were characterized by scanning electron microscopy, X-ray diffraction and Raman spectra. Spectroscopic and electrochemical results revealed that the TiO2NS-rGO nanocomposite is an excellent immobilization matrix with biocompatibility for redox protein, affording good protein bioactivity and stability. Due to the special structure of TiO2NS-rGO (TiO2 nanosheets are perpendicular to rGO substrate), the direct electron transfer of Hb is facilitated and the prepared biosensors displayed good performance for the detection of H2O2 and nitrite with a wide linear range of 0.1-145 mu M for H2O2 and 1-15,000 mu M for nitrite, as well as an extremely low detection limit of 10 nM for H2O2 and 0.21 mu M for nitrite, respectively. The TiO2NS-rGO nanocomposite could be a promising matrix for the fabrication of mediator-free biosensors, and may find wide potential applications in environmental analysis and biomedical detection. Crown Copyright (C) 2014 Published by Elsevier B. V. All rights reserved.