Non-enzymatic Catalytic Oxidation of Glucose and Dual Mode Sensing by Fluorescence/Electrochemical Methods Using MO-GO Composites (MO = ZnO, CuO, NiO and Co3O4)

Nano semiconductors have been recently explored for various electrochemical and optical sensors for remote and non-invasive measurement of biomolecules at lower concentrations. Sensitivity of detection in any technique is influenced by the sensing material employed for detection. Till date, there are no reports on the impact of semiconductor material type on the sensitivity of various glucose detection techniques. In light of these, present study aims to develop nano metal oxide and graphene-metal oxide nanocomposite based electrochemical and optical biosensors for glucose detection and demonstrate the significance of material selection for the two glucose detection techniques. Graphene oxide (GO) and metal oxide (MO:ZnO, CuO, NiO and Co3O4) nanoparticles were synthesized by modified Hummer's method and solution combustion methods respectively, while Graphene-metal oxide nanocomposites (GO-MO) were synthesized by facile hydrothermal method. Morphology and structures of the prepared composite materials were characterised by Raman spectroscopy, XRD and SEM. Glucose sensing was analyzed using Fluorescence (FL) spectroscopy and cyclic voltammetry (CV). Fluorescence emission intensity increased linearly with increase in concentration of glucose for MO nanoparticles, while in case of GO-MO nanocomposites, the emission spectra showed insignificant variation. In case of cyclic voltammetry (CV) measurements, GO-MO nanocomposite modified electrode exhibited excellent glucose sensing compared to MO nanoparticles modified electrode. While MO nanoparticles as glucose sensors were found to be ideal for PL technique, GO-MO nanocomposites were ideal sensing materials for CV technique. The present study thus demonstrates the importance of material selection for specific glucose detection techniques.