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Platinum-gold nanoclusters (PtAu NCs) were electrodeposited on graphene placed on the surface of a glassy carbon electrode (GCE). The PtAu-graphene nanocomposite was characterized by X-ray diffraction, transmission electron microscopy, scanning electron microscopy, and electrochemical methods. The PtAu NCs display excellent electrocatalytic activity towards the reduction of hydrogen peroxide. This effect was exploited in a sensor that responds (at a working voltage of 100 mV) to HO in the 15 nM to 8.73 μM concentration range, with a limit of detection at 8.0 nM. [Figure not available: see fulltext.] [ABSTRACT FROM AUTHOR]

Abstract: Ultrathin platinum-coated gold (Pt@Au) nanoparticles with core@shell structure have been developed by under-potential deposition (UPD) redox replacement technique. A single UPD Cu replacement with Pt2+ produced a uniform Pt monolayer on the surface of gold nanoparticles, which are immobilized on glassy carbon electrode (GCE) surface based on electrostatic interaction. The ultrathin Pt@Au nanoparticles were confirmed by cyclic voltammetry and X-ray photoelectron spectroscopy (XPS). Voltammetry and amperometric methodologies were used to evaluate the electrocatalytic activity of the Pt@Au nanoparticles modified electrode towards the reduction of hydrogen peroxide under the physiological condition. The present results show that ultrathin Pt coating greatly enhances the electrocatalytic activity towards the reduction of hydrogen peroxide, which can be utilized to fabricate the hydrogen peroxide sensor. Chronoamperometric experiments showed that at an applied potential of 0.08V (vs. Ag/AgCl), the current reduction of hydrogen peroxide was linear to its concentration in the range of 1–450μΜ, and the detection limit was found to be 0.18μM (signal-to-noise ratio, S/N=3). [Copyright &y& Elsevier]

Abstract: Based on the enhancement of chemiluminescence (CL) of luminol-hydrogen peroxide-gold nanoparticles system by fluoroquinolones (FQs), a novel and rapid CL method is reported for the determination of FQs derivatives. Under the optimum conditions, the CL intensity is proportional to the concentration of FQs derivative in solution. The corresponding linear regression equations are established over the range of 0.08–1.28μg/mL for norfloxacin, 0.013–1.32μg/mL for ciprofloxacin, 0.014–1.4μg/mL for lomefloxacin, 0.029–1.46μg/mL for fleroxacin, 0.02–1.0μg/mL for ofloxacin and 0.01–1.44μg/mL for levofloxacin, respectively. The limits of detection (S/N =3) are 3.2, 9.5, 7.0, 9.0, 8.0, and 8.0ng/mL with the relative standard deviation (n =11) 4.3, 1.5, 1.9, 1.3, 1.6 and 2.1% for norfloxacin, ciprofloxacin, lomefloxacin, fleroxacin, ofloxacin and levofloxacin, respectively. This proposed method has been applied to detect FQs derivatives in human urine successfully. [Copyright &y& Elsevier]