Titania nanoparticles modified reduced graphene oxide nanocomposite with a double-layered structure encapsulating hemoglobin for a mediator-free biosensor

Abstract Titania nanoparticles modified reduced graphene oxide (TiO 2 NPs–rGO) nanocomposite with a double-layered structure has been synthesized and used to immobilize hemoglobin (Hb) in order to fabricate a mediator-free biosensor. The morphology and structure of the TiO 2 NPs–rGO nanocomposite were characterized by scanning electron microscopy, X-ray diffraction and Raman spectra. Spectroscopic and electrochemical researches revealed that the TiO 2 NPs–rGO nanocomposite could be an excellent immobilization matrix with biocompatibility for redox protein, affording good protein bioactivity and stability. Due to the special double-layered structure of TiO 2 NPs–rGO, the direct electron transfer of Hb is facilitated and the prepared biosensor exhibited a good performance for the detection of H 2 O 2 , with a extremely low detection limit of 10 nM, as well as a wide linear range of 0.1–140 μM. The TiO 2 NPs–rGO nanocomposite with the double-layered structure could be a promising matrix for the fabrication of mediator-free biosensors, and may find wide potential applications in biomedical detection and environmental analysis.