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Abstract: Using chitosan as an effective linker between CMK-3 and glassy carbon electrode surface, {Hb/CMK-3} n multilayer film-modified electrodes were constructed through layer-by-layer assembly. The morphology of thus-formed {Hb/CMK-3} n film was characterized by scanning electron micrographs, and the interaction of hemoglobin (Hb) with CMK-3 was studied by UV–vis spectroscopy and electrochemical methods. Under optimal conditions, {Hb/CMK-3}6 film showed a couple of stable and well-defined redox peaks at about −377 and −296mV in pH 7.0 buffers. Furthermore, the {Hb/CMK-3}6 film displayed excellent electrocatalysis to the reduction of both H2O2 and O2. Based on thus-formed film and its direct electron transfer behavior, a novel biosensor was presented for the determination of H2O2 ranging from 1.2 to 57μM with the detection limit of 0.6μM at S/N=3. CMK-3 provided a desirable matrix for protein immobilization and biosensor preparation. [Copyright &y& Elsevier]

Abstract: Potassium (K) doping plays a critical role in adjusting the electronic properties of carbon materials. In this work, K-doped graphene, as a new electrode material, was used to modify glassy carbon electrode (GCE) for the simultaneous determination of nitrite (NO2 −) and sulfite (SO3 2−) under neutral conditions. The advantages of K-doped graphene/GCE are illustrated from comparison with the graphene/GCE, K-doped multi-walled carbon nanotubes (MWNTs)/GCE, MWNTs/GCE, graphite/GCE and bare/GCE for electrocatalytic and sensing applications. It exhibited a linear response over the concentration range from 0.5μM to 3.9mM, with a detection limit of 0.2μM (S/N=3) for NO2 − and a corresponding linear range of 2.5μM to 10.3mM, with a detection limit of 1.0μM (S/N=3) for SO3 2−. The proposed sensor could be successfully applied in the simultaneous detection of residual NO2 − and SO3 2− in polluted water accurately and precisely. [Copyright &y& Elsevier]

Abstract: Herein, we demonstrated a facile strategy for preparing high-loading Au nanoparticles using thionine functionalized graphene oxide as the supporting material. Glassy carbon electrodes modified with the as-obtained nanocomposites showed remarkably electrocatalytic activity towards the oxidation of glucose, leading to an enzymeless glucose sensor with a wide linear range and a lower detection limit of 0.05μmol/L. [Copyright &y& Elsevier]