Synthesis of gold nanoclusters/glucose oxidase/graphene oxide multifunctional catalyst with surprisingly enhanced activity and stability and its application for glucose detection

The paper reports the synthesis of gold nanoclusters/glucose oxidase/graphene oxide (GNC/GOD/GO) multifunctional catalyst and its application for glucose detection. First, an amine group was introduced into the GO sheet through the 1-ethyl-3-(3-dimethylaminopropyl)carbodiimide/N-hydroxysuccinimide mediated reaction between carboxylic acid and ethylenediamine to form a positively charged GO sheet (GO-NH3+). Then, negatively charged GNC and GOD were assembled on the surface of GO-NH3+ with electrostatic interaction. Finally, the hybrid was dried by freeze drying. The resulting hybrid gives high fluorescence intensity and optical stability. More importantly, the hybrid exhibits largely enhanced activities towards the decomposition of hydrogen peroxide and oxidation of glucose at neutral pH. Owing to the greatly synergistic catalytic effect between GNC and GOD, the nanosensor based on the hybrid displays an ultrasensitive fluorescence response to glucose. The fluorescence peak intensity linearly decreases with the increase of glucose concentration in the range of 1.1 x 10(-2) to 1.6 x 10(-7) M with a detection limit of 6.8 x 10(-8) M (S/N = 3). The method provides the advantage of sensitivity, repeatability and stability compared with present glucose sensors. It has been successfully applied in detection of glucose in real serum samples. The study also opens a new avenue for the fabrication of GO-based catalytic materials that holds great promise in potential applications such as biocatalyst, nanosensors and molecular carriers.