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

Titania nanoparticles modified reduced graphene oxide (TiO2NPs–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 TiO2NPs–rGO nanocomposite were characterized by scanning electron microscopy, X-ray diffraction and Raman spectra. Spectroscopic and electrochemical researches revealed that the TiO2NPs–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 TiO2NPs–rGO, the direct electron transfer of Hb is facilitated and the prepared biosensor exhibited a good performance for the detection of H2O2, with a extremely low detection limit of 10 nM, as well as a wide linear range of 0.1–140 μM. The TiO2NPs–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.