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Multifunctional magne-tic composite microspheres which possess the precise control of the size, morphology, surface chemistry, and assembly process of each component have been successfully prepared. These functional nanocomposite microspheres possess a core of silica-protected magnetite particles and in situ growth active gold nanoparticles (ca. 4 nm) on the outer shell by layer-by-layer electrostatic self-assembly. The well-designed microspheres have high magnetization (23.9 emu/g), uniform sphere size (ca. 500 nm), and stably confined and active small Au nanoparticles. As a result, the very little composite microspheres show high performance in catalytic reduction of 4-nitrophenol (with conversion of 95% in 12 min), special convenient magnetic separability, long life, and good reusability. The unique nanostructure makes the microsphere a novel stable and highly efficient catalyst system for various catalytic industry processes.

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Graphene was successfully prepared and well separated to individual sheets by introducing ÀSO 3 À . XRD and TEM were employed to characterize the graphene. UV-visible absorption spectra indicated that glucose oxidase (GOx) could keep bioactivity well in the graphene-Au biocomposite. To construct a novel glucose biosensor, graphene, Au and GOx were co-immobilized in Nafion to further modify a glassy carbon electrode (GCE). Electrochemical measurements were carried out to investigate the catalytic performance of the proposed biosensor. Cyclic voltammograms (CV) showed the biosensor had a typical catalytic oxidation response to glucose. At the applied potential þ 0.4 V, the biosensor responded rapidly upon the addition of glucose and reached the steady state current in 5 s, with the present of hydroquinone. The linear range is from 15 mM to 5.8 mM, with a detection limit 5 mM (based on the S/N ¼ 3). The Michaelis-Menten constant was calculated to be 4.4 mM according to Lineweaver -Burk equation. In addition, the biosensor exhibits good reproducibility and long-term stability. Such impressive properties could be ascribed to the synergistic effect of graphene-Au integration and good biocompatibility of the hybrid material.Keywords: Glucose biosensor, Graphene, Au nanoparticles, Electrocatalytic oxidation, Synergistic effect, Biosensors, NanoparticlesThe determination of glucose is very important in industry [1], clinical diagnostics [2], environmental monitoring [3] and food processing [4]. Especially for the patients who suffer from diabetes, the monitoring of blood glucose concentration must be taken momently. For the purpose to design highly sensitive, selective and stable biosensor, numerous materials have been attempted to modify electrode, including metal nanoparticles [5,6], conducting polymer [7,8], semiconductor quantum dots [9] and carbon nanotube (CNT) [10 -12]. Among them, CNT has been utilized most widely due to a few unique properties it possesses, such as excellent mechanical strength, high surface area, good chemical stability and outstanding electrical conductivity [13]. However, to most CNT synthesis methods, metal catalyst residues can not be completely removed even after iterative purification, leading to some unexpected results [14,15]. In addition, CNT is highcost and large scale synthesis-prohibitive. Therefore, there is always a demand of finding an affordable alternative to CNT for sensors fabrication.Graphene, which was characterized as the thinnest material in our universe [16], has attracted more and more attention since it was firstly obtained by a scotch tape method in laboratory [17]. Graphene is the name given to a flat monolayer of carbon atoms tightly packed into a twodimensional (2D) honeycomb lattice, and is a basic building block for graphitic materials of all other dimensionalities [18]. The unique properties of graphene involve of high surface area-to-volume ratio, excellent thermal conductivity and mechanical stiffness. Most prominently, carriers in an ideal graphene she...