Biomolecule‐Doped Organic/Inorganic Hybrid Nanocomposite Film for Label‐Free Electrochemical Immunoassay of α‐1‐Fetoprotein

A new electrochemical immunosensor for the detection of α‐1‐fetoprotien (AFP) was developed based on AFP antibody (anti‐AFP)‐functionalized organic/inorganic hybrid nanocomposite membrane. To fabricate such a hybrid composite membrane, 3,4,9,10‐perylenetetracarboxylic acid‐bound thionine molecules (PTCTH) were initially doped into titania colloids (TiO₂), and then gold nanoparticles and anti‐AFP were immobilized onto the composite film in turn. Comparison with the electrode fabricated only with thionine not 3,4,9,10‐perylenetetracarboxylic acid, the immunosensor with PTCTH exhibited high sensitivity and fast electron transfer. The presence of gold nanoparticles provided a good microenvironment for the immobilization of biomolecules, enhanced the surface coverage of protein, and improved the sensitivity of the immunosensor. The modified process was characterized by scanning electron microscope (SEM), cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS). The surface topography of the membrane was investigated by scanning electron microscopy (SEM). Under optimal conditions, the proposed immunosensor exhibited a wide linear range from 2.5 to 200.0 ng/mL towards AFP with a detection limit of 0.5 ng/mL (S/N=3). The stability, reproducibility and precision of the immunosensor were acceptable. Comparison with the conventional enzyme‐linked immunosorbent assay (ELISA), the present method did not require more labeled procedures and washing steps. Significantly, the detection methodology provides a promising approach for other proteins or biosecurities.     

An Organic‐Inorganic Hybrid Based on Keggin‐Type Polyoxometalate and Hypoxanthine: Synthesis,Structure, Stability,and Electrochemistry Properties

The organic‐inorganic hybrid H₅[Ag₂(hyp)₂]₂[BW₁₂O₄₀] · 9H₂O ( 1 ) (hpy = hypoxanthine), based on Keggin‐type polyoxometalate and hypoxanthine, was prepared by hydrothermal synthesis and characterized by single‐crystal and powder X‐ray diffraction, IR spectroscopy, elemental analysis, and thermogravimetry. The title compound has a two‐dimensional layer structure constructed by Keggin‐type [BW₁₂O₄₀]^5– anion, silver, and the biomolecule hyp. In addition, compound 1 exhibited excellent stability and superior activity in the electro‐catalytic oxidation of glucose.     

Amperometric Biosensor Based on Immobilization Acetylcholinesterase on Manganese Porphyrin Nanoparticles for Detection of Trichlorfon with Flow‐Injection Analysis System

A highly sensitive amperometric biosensor for the detection of organophosphate pesticides (OPs) is developed. The biosensor was fabricated by immobilized acetylcholinesterase (AChE) on manganese (III) meso‐tetraphenylporphyrin (MnTPP) nanoparticles (NPs)‐modified glassy carbon (GC) electrode. The MnTPP NPs used in this article were synthesized by mixing solvent techniques. AChE enzyme was immobilized on the MnTPP NPs surface by conjugated with chitosan (CHIT). The electrocatalytic activity of MnTPP NPs led to a greatly improved performance for thiocholine (TCh) product detection. The developed AChE‐CHIT/MnTPPNP/GC biosensor integrated with a flow‐injection analysis (FIA) system was used to monitor trichlorfon (typical OP). A wide linear inhibition response for trichlorfon is observed in the range of 1.0 nM–1.0 mM, corresponding to 10–83% inhibition for AChE with a detection limit of 0.5 nM.     

Flow Injection Analysis of Maleic Hydrazide Using an Electrochemical Sensor Based on Palladium‐Dispersed Carbon Paste Electrode

A new analytical methodology for the electrochemical detection of the herbicide maleic hydrazide (3,6‐dihydroxypyridazine) by flow injection analysis is presented. This method is supported by the novel application of a palladium‐dispersed carbon paste electrode as an amperometric sensor for this herbicide. Maleic hydrazide shows anodic electrochemical activity on carbon‐based electrodes (glassy carbon or carbon paste electrodes) in all the pH range. This electrochemical activity is enhanced using metal‐dispersed carbon paste electrodes, especially at Pd‐dispersed CPE which displays good oxidation signals at 690 mV (0.050 M phosphate buffer pH 7.0), 140 mV lower than at unmodified electrodes. Under the optimized conditions, the electroanalytical performance of Pd‐dispersed CPE in flow injection analysis was excellent, with good reproducibility (RSD 3.3%) and a wide linear range (1.9×10^?7 to 1.0×10^?4 mol L^?1). A detection limit of 1.4×10^?8 mol L^?1 (0.14 ng maleic hydrazide) was obtained for a sample loop of 100 μL at a fixed potential of 700 mV in 0.050 M phosphate buffer solution at pH 7.0 and a flow rate of 2.0 mL min^?1. The proposed method was applied for the maleic hydrazide detection in natural drinking water samples.     

Ethylene/1‐Hexene Copolymerization with A Novel SiO2‐Supported Inorganic and Organic Hybrid Chromium‐based Catalyst

In this work, ethylene/1‐hexene copolymerization with a novel SiO₂‐supported inorganic and organic hybrid chromium‐based catalyst was investigated. This catalyst was prepared using the residual surface hydroxyl groups in Phillips catalyst to support bis(triphenylsilyl) chromate (BC) in order to get the merits from two important chromium‐based catalysts namely inorganic Phillips and organic S‐2 catalysts. The influences of addition amount of 1‐hexene and BC were systematically investigated. With increasing 1‐hexene from 0 to 7 vol%, the activity of HCat‐2 catalyst showed a decreasing tendency. Its copolymer also showed the better short chain branches distribution through the temperature rising elution fractionation cross successive self‐nucleation and annealing characterization.

     

Preparation,Characterization, and Electrocatalytic Properties of Mixed‐Valent Nickel Hexacyanoferrate/Phosphomolybdate Hybrid Film Electrodes Towards Oxidation of Ascorbic Acid and Reduction of S2O$\rm{ {_{8}^{2-}}}$

Polynuclear mixed‐valent nickelhexacyanoferrate/phosphomolybdate (NiHCF/PMo), nickel/phosphomolybdate (Ni/PMo) hybrid films were prepared on glassy carbon electrode by multiple scan cyclic voltammetry. Combination of individual components gave the opportunity to fabricate hybrid film with tunable electrochemical and analytical properties compared to individual components. The film growth was monitored using electrochemical quartz crystal microbalance (EQCM). The cyclic voltammogram of the nickelhexacyanoferrate/phosphomolybdate film is characterized by four redox couple whereas nickel/phosphomolybdate hybrid film exhibits three redox couples. Cyclic voltammetric features suggest that the charge transfer process in both films resembles that of surface‐confined redox species. The voltammetric response of nickelhexacyanoferrate/phosphomolybdate film electrode was found to be depending on the pH of the contacting solution. Electrocatalytic behavior of nickel/phosphomolybdate hybrid film coated electrodes toward oxidation of ascorbic acid and reduction of sulfur oxoanion, S₂O , was investigated using cyclic voltammetry technique. Analytical application of nickel/phosphomolybdate hybrid film electrode was tested in amperometry and flow injection analysis.     

A Novel Electrochemical Method for the Analysis of Hydrogen Peroxide with the Use of a Glassy Carbon Electrode Modified by a Prussian Blue/Copper‐Gold Bimetallic Nanoparticles Hybrid Film

A novel Prussian blue/copper‐gold bimetallic nanoparticles hybrid film modified electrode was prepared by electrochemical deposition on a glassy carbon electrode (PB/Cu‐AuNPs/GCE). Morphology and electrochemistry of this electrode were studied by UV‐vis spectroscopy, scanning electron microscopy, X‐ray diffraction, cyclic voltammetry and electrochemical impedance spectroscopy. The sensor showed significantly better electrocatalytic activity for the reduction of hydrogen peroxide in comparison with the single PB/GCE and PB/AuNPs/GCE. This was attributed to the synergistic effect of PB and Cu‐Au bimetallic nanoparticles. Also, the sensor demonstrated an overall high level of performance for the analysis of H₂O₂ in the concentration range from 0.002 to 0.84 mM.