Zinc oxide nanoparticles-reduced graphene oxide nanocomposite thin-film for β-D-glucose detection

This work presents a technique to detect β-D-glucose by using zinc oxide nanoparticles-reduced graphene oxide (ZnO NPs-rGO) nanocomposite thin-film. The ZnO NPs were synthesized by the direct precipitation method. The rGO was fabricated via hydrothermal treatment of graphene oxide (GO) powder. The optical properties of the nanocomposite thin-film were characterized via ultraviolet–visible, Raman and photoluminescence (PL) spectrometers. The morphology of the nanocomposite thin-film was obtained from a field emission scanning electron microscope (FESEM). Based on the optical result, the absorption peak was correlated with the excitation wavelength required to induce high PL spectra in the nanocomposite. Furthermore, the FESEM image displayed the spherical and non-uniform sized ZnO NPs on the sheet-like surface of rGO. For the β-D-glucose detection, changes in the wavelength and intensity peak of UV emission in PL spectra were investigated. From the results, a red-shift and reduction of peak intensity of UV emission was observed under 0.25 - 40 mM β-D-glucose concentration. A linear response, with a slope of 0.87 nm/mM and regression coefficient, R2 of 0.99 indicated that the detection range of the nanocomposite thin-film covers from high to low glucose levels. Furthermore, the highest sensitivity of 1.09 %/mM was obtained based on the percentage change of the peak intensity per mM glucose concentration. These observations signify the potential of detecting wide concentrations of β-D-glucose, making the nanocomposite material suitable for practical uses in glucose sensing and monitoring.