Synthesis Of Graphene-metal Oxide Nanocomposite And Their Application In Eletrochemical Sensing

Direct electrochemistry of redox proteins has attracted considerable recent attention since it provides a foundation for the construction of third-generation biosensors. Nanotechnology provides a new way to construct the third-generation biosensor. Nanomaterials have unique optical, electrical and catalytic properties and large surface area, good biocompatibility, which can greatly enhance the direct electron transfer of proteins and promote the biosensor performance. The object of this dissertation is to explore different graphene-based nanocomposite for fabrication the third-generation biosensors. More details are summarized below:(1) Ti O2 nanosheet modified reduced graphene oxide(TiO2NS-rGO) nanocomposite has been synthesized and then used to immobilise hemoglobin(Hb) to fabricate a mediator-free biosensor. The morphology and structure of the TiO2NS-r GO were characterized by scanning electron microscopy, X-ray diffraction and Raman spectra. Spectroscopic results revealed that the TiO2NS-r GO nanocomposite was an excellent immobilization matrix with biocompatibility for redox protein, affording good protein bioactivity and stability. Electrochemical results revealed that the direct electron transfer of Hb was facilitated and the as-prepared biosensors displayed good performance for the detection of H2O2 with a wide linear range of 0.1-145 μM for H2O2 and an extremely low detection limit of 10 n M for H2O2, as well as a fast response and excellent long-term stability.(2) TiO2 nanoparticle modified reduced graphene oxide(Ti O2NP-r GO) nanocomposite has been synthesized and then used to immobilise hemoglobin(Hb) to fabricate a mediator-free biosensor. The morphology and structure of the TiO2NP-r GO were characterized by scanning electron microscopy, X-ray diffraction and Raman spectra. Spectroscopic results revealed that the TiO2NP-r GO nanocomposite was an excellent immobilization matrix with biocompatibility for redox protein, affording good protein bioactivity and stability. Electrochemical results revealed that the direct electron transfer of Hb was facilitated and the as-prepared biosensors displayed good performance for the detection of H2O2 with a wide linear range of 0.1-140 μM for H2O2 and a low detection limit of 10 nM for H2O2, as well as a fast response and excellent long-term stability.(3) WO3 nanowire modified reduced graphene oxide(WO3NW-rGO) nanocomposite has been synthesised and then used to immobilise hemoglobin(Hb) to fabricate a mediator-free biosensor. The morphology and structure of the WO3NW-r GO were characterized by scanning electron microscopy, transmission electron microscope, X-ray diffraction and Raman spectra. Spectroscopic results revealed that the WO3NW-rGO was an excellent immobilization matrix with biocompatibility for redox protein, affording good protein bioactivity and stability. Electrochemical results revealed that the direct electron transfer of Hb was facilitated and the as-prepared biosensors displayed good performance for the detection of H2O2 with a wide linear range of 0.1-170 μM for H2O2 and a low detection limit of 0.1 μM for H2O2, as well as a fast response and excellent long-term stability.(4) Flower-like WO3 modified reduced graphene oxide(WO3(F)-r GO) nanocomposite has been synthesised and then used to immobilise hemoglobin(Hb) to fabricate a mediator-free biosensor. The morphology and structure of the WO3(F)-rGO were characterized by scanning electron microscopy, X-ray diffraction and Raman spectra. Spectroscopic results revealed that the WO3NW-rGO was an excellent immobilization matrix with biocompatibility for redox protein, affording good protein bioactivity and stability. Electrochemical results revealed that the direct electron transfer of Hb was facilitated and the as-prepared biosensors displayed good performance for the detection of H2O2 with a wide linear range of 0.1-130 μM for H2O2 and an extremely low detection limit of 0.1 μM for H2O2, as well as a fast response and excellent long-term stability.