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Abstract Novel enzyme mimic materials with excellent analytical properties and stable structure are essential for detecting H 2 O 2 in many fields. In the present work, we prepare PtNi alloy/CeO 2 plates/N-doped carbon nanofibers (PtNi/CeO 2 /NCNFs) via heat-treating the electrospun nanofiber hybrid of polyvinyl pyrrolidone and inorganic metal salts. Structural analysis indicate that PtNi alloy nanoparticles disperse on or around CeO 2 nanoplates and PtNi alloy/CeO 2 plates uniformly embed in porous NCNFs. A possible formation mechanism of PtNi alloy/CeO 2 plates in NCNFs is put forward based on the electrostatic interaction of Ce3+, P t C l 6 2 − and Ni2+. The special structure of PtNi/CeO 2 /NCNFs can initiate the synergistic effect and enhance its enzyme-like electrocatalytic activity toward the reduction of H 2 O 2. The PtNi/CeO 2 /NCNFs-based sensor displays outstanding performances for H 2 O 2 detection with wide linear range of 0.5 μM–15 mM, high sensitivity of 345.0 μA mM−1 cm−2, low detection limit of 0.025 μM, high selectivity and anti-interference. Besides, the sensor possesses superior reproducibility and good stability. The RSD value of response current obtained from five parallel experiments is evaluated to be 2.36% and PtNi/CeO 2 /NCNFs-GCE can still remain 98.5% of the initial response current value after being stored at 25 °C for 15 days. More importantly, the constructed sensor can be applied to detection of H 2 O 2 content in cosmetics with satisfactory recovery (95.8%–103.8%) and low relative standard deviation (< 4.5%). These attractive properties make it possible for PtNi/CeO 2 /NCNFs to analyze H 2 O 2 in real samples. Graphical abstract Image 1 Highlights • PtNi/CeO 2 /NCNFs with embedded structure was designed. • PtNi alloy dispersed on or around CeO 2 nanoplates was in-situ synthesized in NCNFs. • PtNi/CeO 2 /NCNFs-based sensor exhibited excellent properties for H 2 O 2 sensing. • PtNi/CeO 2 /NCNFs-based sensor was applied to detection of H 2 O 2 in cosmetics. [ABSTRACT FROM AUTHOR]

Abstract: In this paper, we report on one-pot synthesis of Ag nanoparticles/reduced graphene oxide (AgNPs/rGO) nanocomposites by heating mixed solution of graphene oxide (GO) and AgNO3 with the use of diethylenetriamine as a reducing agent at 80°C for 30min. Several analytical techniques including UV–vis spectroscopy, Raman spectroscopy and transmission electron microscopy (TEM) have been employed to characterize the resulting nanocomposites. It was found that such nanocomposites exhibit good catalytic activity toward the reduction of H2O2. This nonenzymatic H2O2 sensor shows a fast amperometric response time of less than 2s. The linear detection range is estimated to be from 0.1 to 100mM (r =0.999), and the detection limit is estimated to be 3.6μM at a signal-to-noise ratio of 3. [Copyright &y& Elsevier]

Abstract: Ag nanoparticles-decorated reduced graphene oxide (AgNPs-rGO) has been successfully fabricated through a one-step strategy, carried out by hydrothermal treatment of the mixture of AgNO3 and GO solution under strong alkaline conditions at 180°C for 30min. The reaction was accomplished without extra reducing agent and surface modifier. As-synthesized AgNPs-rGO has been successfully applied in catalytic performance toward the reduction of H2O2. This H2O2 sensor shows a wide linear range of 0.1–60mM (r =0.991) and a low detection limit of 1.80μM at a signal-to-noise ratio of 3. [Copyright &y& Elsevier]

Abstract: In this study, we report on the electrocatalytic behaviour of a polypyrrole/magnetite hybrid electrode towards the reduction of hydrogen peroxide. The electrocatalytic activity of the composite electrode was demonstrated by cyclic voltammetric and chrono-amperometric measurements in comparison with the identically prepared neat polymer film. The stationary reduction currents, measured at an appropriately chosen potential (here at E =−0.3V), plotted against the peroxide concentration gave a perfect linear correlation in nitrogen atmosphere in the micromolar concentration range. The performance of the composite electrode was not affected by the presence of sulphate, nitrate or chloride anions. In the presence of dissolved oxygen a complex electrocatalytic activity was observed, involving the reduction of both oxygen and H2O2. However, a linear dependence was found also in oxygen containing media, although with much higher currents, but with the same slope (even at different oxygen concentrations). This fact may trigger the development of such hybrid electrodes towards hydrogen peroxide sensors in different aqueous (including natural) samples. [Copyright &y& Elsevier]

Abstract: In this paper, we report on the one-step preparation of Ag nanoparticle (AgNP)-decorated coordination polymer nanobelts, carried out by direct mixing of an aqueous AgNO3 solution and a N,N-dimethylformamide (DMF) solution of 4,4′-bipyridine (BPD) at room temperature. The construction of an enzymeless H2O2 sensor using such nanocomposites with a detection limit of 0.9μM is also demonstrated. [Copyright &y& Elsevier]

Abstract: Nanoporous gold (NPG) fabricated by dealloying Au–Ag film was investigated for the non-enzymatic detection of H2O2. The apparent activation energy of H2O2 electrochemical reduction on NPG was found to be as low as ∼30kJmol−1. The reduction currents at −0.4V vs. SCE demonstrated a strict linear dependence in a wide H2O2 concentration region from 10μM to 8mM with a detection limit 3.26μM. Furthermore, the biosensor based on NPG exhibited high selectivity, good reproducibility, and long-term stability. These results indicate that NPG could be a promising electrochemical material for H2O2 detection. [Copyright &y& Elsevier]

Abstract: A simple procedure was developed to prepare a glassy carbon (GC) electrode modified with nickel oxide (NiOx) nanoparticles and water-soluble dyes. By immersing the GC/NiOx modified electrode into thionine (TH) or celestine blue (CB) solutions for a short period of time (5–120s), a thin film of the proposed molecules was immobilized onto the electrode surface. The modified electrodes showed stable and a well-defined redox couples at a wide pH range (2–12), with surface confined characteristics. In comparison to usual methods for the immobilization of dye molecules, such as electropolymerization or adsorption on the surface of preanodized electrodes, the electrochemical reversibility and stability of these modified electrodes have been improved. The surface coverage and heterogeneous electron transfer rate constants (k s) of thionin and celestin blue immobilized on a NiOx-GC electrode were approximately 3.5×10−10 molcm−2, 6.12s−1, 5.9×10−10 molcm−2 and 6.58s−1, respectively. The results clearly show the high loading ability of the NiOx nanoparticles and great facilitation of the electron transfer between the immobilized TH, CB and NiOx nanoparticles. The modified electrodes show excellent electrocatalytic activity toward hydrogen peroxide reduction at a reduced overpotential. The catalytic rate constants for hydrogen peroxide reduction at GC/NiOx/CB and GC/NiOx/TH were 7.96(±0.2)×103 M−1 s−1 and 5.5(±0.2)×103 M−1 s−1, respectively. The detection limit, sensitivity and linear concentration range for hydrogen peroxide detection were 1.67μM, 4.14nAμM−1 nAμM−1 and 5μM to 20mM, and 0.36μM, 7.62nAμM−1, and 1μM to 10mM for the GC/NiOx/TH and GC/NiOx/CB modified electrodes, respectively. Compared to other modified electrodes, these modified electrodes have many advantages, such as remarkable catalytic activity, good reproducibility, simple preparation procedures and long-term stabilities of signal responses during hydrogen peroxide reduction. [Copyright &y& Elsevier]

l An L012@PAni-PAAm hydrogel composite was prepared on glassy carbon electrode and used as a novel ECL biosensor. l The L012@PAni-PAAm hydrogel composite-based ECL biosensor presents good stability, high selectivity, wide detection range (0.01–50 μM) and high detection sensitivity (limit of detection of 2.9 nM) of H 2 O 2. l The ECL biosensor was sucessfully applied to in situ detect H 2 O 2 produced by cardiomyocytes. Detection of hydrogen peroxide (H 2 O 2) released from cardiomyocytes is vital for pathological and physiological studies of cardiovascular diseases (CVD). Electrochemiluminescence (ECL) method has been widely utilized to monitor cellular H 2 O 2 owing to its advantages of high sensitivity and specificity. In this work, we proposed a novel ECL biosensor based on an L012@PAni-PAAm hydrogel composite for in situ monitoring H 2 O 2 produced from cardiomyocytes. Besides the decent porosity for cell adhesion, favorable biocompatibility for cell incubation and high permeability for H 2 O 2 diffusion, the L012@PAni-PAAm hydrogel composite exhibited good conductivity for triggering ECL reaction and high detection sensitivity of H 2 O 2. The L012@PAni-PAAm hydrogel composite-based ECL biosensor showed low background signal, good stability, high selectivity, wide detection range (0.01–50 μM) and high detection sensitivity (limit of detection of 2.9 nM) of H 2 O 2. Thus, it was successfully applied to in situ detect H 2 O 2 produced from cardiomyocytes. The ECL biosensor developed in our work can be used as a new highly sensitive biosensor for in situ detection of cellular H 2 O 2 for physiological and pathological studies. A novel ECL biosensor based on L012@PAni-PAAm hydrogel composite modified GCE was developed and used to in situ monitor H 2 O 2 produced from cardiomyocytes. Image, graphical abstract [ABSTRACT FROM AUTHOR]

Microelectrode array (MEA) has recently attracted significant research interest in biomedical applications due to its high sensitivity, mass production and fast response. However, the previous MEA with precious metal-based nanomaterials for electro-catalysis may induce toxicity to cells. In this work, we present a metal-free graphene/graphene oxide (rGO/GO) hybrid MEA for precise and in-situ H 2 O 2 secretion detection. The configuration and size of rGO/GO hybrid MEA can be well designed and controlled by combining the convenient lithography and electrochemistry method, where the GO region with abundant oxygen functionalized groups has good biocompatibility, so as to play as the adhesion and growth agent of pheochromocytoma cells (PC12 cells). Whereas, the rGO region with higher electro-catalytic activity can favor high sensitive in-situ H 2 O 2 secretion detection that is released from the stimulated PC 12 cells at GO region, but with the cell filopodia extended to the rGO region. Besides, the rGO/GO hybrid MEA presented herein is compatible with the micro-fabrication technique and can be integrated into the lab-on-chip devices, which may shed useful insights for the design and fabrication of high performance biosensors. Image 1 • Metal-free rGO/GO hybrid microelectrode array. • Precise and in-situ H 2 O 2 secretion detection released by stimulated cells. • Configuration and size of rGO/GO hybrid MEA are controlled. • Cell filopodia extended to rGO region with high electro-catalytic activity. [ABSTRACT FROM AUTHOR]