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By employing dopamine as a nitrogen source and reducing agent, the block copolymer P123 as a pore forming agent, and graphene oxide as a carbon precursor, we present, for the first time, a convenient and controllable approach to the preparation of a novel uniformly nitrogen doped porous graphene (N-PGR) material. Using the prepared N-PGR as the supporting material, a novel nitrogen doped porous graphene/Pt nanoflower material (Pt/N-PGR) was obtained by a green and simple method. The characterization results of scanning electron microscopy (SEM), element mapping, transmission electron microscopy (TEM) and X-ray photoelectron spectroscopy (XPS) demonstrate that Pt nanoflowers are uniformly dispersed on nitrogen doped porous graphene. Electrochemical measurements show that Pt/N-PGR-900/GCE exhibits improved electrocatalytic activity towards H2O2 reduction and glucose oxidation. Linear responses are found for H2O2 and glucose in the range of 0.5–40 326 μM and 0.5–133.5 mM with the detection limit (S/N = 3) of 0.2 μM and 0.05 mM, respectively. In addition, Pt/N-PGR-900/GCE exhibits high sensitivity and good anti-interference ability. The superior catalytic activity and selectivity make Pt/N-PGR a promising nanomaterial for application in electrochemical biosensing studies. [ABSTRACT FROM AUTHOR]

An electrochemical immunosensor for quantitative detection of α-fetoprotein (AFP) in human serum was developed using graphene sheets (GS) and thionine (TH) as electrode materials and mesoporous silica nanoparticles (MSNs) loaded with ferroferric oxide (Fe 3 O 4 ) nanoparticles and horseradish peroxidase (HRP) as labels for signal amplification. In this study, the compound of GS and TH (GS–TH) was used as a substrate for promoting electron transfer and immobilization of primary antibody of AFP (Ab 1 ). MSNs were used as a carrier for immobilization of secondary antibody of AFP (Ab 2 ), Fe 3 O 4 , and HRP. The synergistic effect occurred between Fe 3 O 4 and HRP and greatly improved the sensitivity of the immunosensor. This method could detect AFP over a wide concentration range from 0.01 to 25 ng ml −1 with a detection limit of 4 pg ml −1 . This strategy may find wide potential application in clinical analysis or detection of other tumor markers. [ABSTRACT FROM AUTHOR]

Abstract: In the present work, using copper as an etching agent, a novel and easy method to prepare porous graphene nanosheet (P-GR) was reported. With a large number of pores, more acidic groups and edge defect sites (EDSs) compared with graphene (GR), the prepared P-GR was used as an electrochemical biosensing platform for the first time. Using voltammetry and amperometry as detection methods, some important electroactive compounds, including dopamine (DA), ascorbic acid (AA), uric acid (UA), epinephrine (EP), guanine (G), adenine (A), xanthine (XA), hypoxanthine (HX), hydrogen peroxide and β-nicotinamide adenine dinucleotide (NADH) were employed to study their electrochemical responses on P-GR modified glassy carbon electrode (P-GR/GCE). The results show that P-GR/GCE exhibits better electrochemical performance to these substances compared with GR modified glassy carbon electrode (GR/GCE) and edge plane pyrolitic graphite electrode (PGE). The remarkable electrochemical advantage of P-GR makes it a promising material in electrochemical biosensing field. [Copyright &y& Elsevier]

Abstract: A rapid, environmental friendly, and sensitive biosensor for detection of zearalenone (ZEN) was developed at glassy carbon electrode (GCE) using nanoporous bimetallic alloy as label of secondary antibody (Ab2). The biosensor was prepared by immobilizing nitrogen-doped graphene sheets (N-GS) captured primary antibody (Ab1) on GCE. The analytes were then bound to Ab1 for further capture of antibodies, labeled by the nanoporous bimetallic alloy, nanoporous PtCo alloy (NP-PtCo). NP-PtCo with three-dimensional bicontinuous spongy structures and various hollow channels was prepared by corrosion of PtCoAl alloy, and exhibited remarkably improved electrocatalytic activity toward H2O2. Within ZEN concentration range (0.005–25ngmL−1), the biosensor exhibited a highly sensitive response to ZEN with a detection limit of 2.1pgmL−1. Several factors that would affect the performance of the biosensor were studied, such as erosion time of NP-PtCo, concentration of NP-PtCo, pH of buffer solution, and concentration of N-GS. After H2O2 was injected into the buffer solution, the amperometric response of the biosensor can be used to detect ZEN by chronoamperometry. The developed biosensor shows good selectivity and sensitivity to ZEN and is promising in feed safety analysis. [Copyright &y& Elsevier]