Nanoscale Au-In alloy-oxide core-shell particles as electrocatalysts for efficient hydroquinone detection

The presence of hydroquinone (HQ), a phenol ubiquitous in nature and widely used in industry, needs to be monitored because of its toxicity to the environment. Here we demonstrate efficient detection of HQ using simple, fast, and noninvasive electrochemical measurements on indium tin oxide (ITO) electrodes modified with nanoparticles comprising bimetallic Au–In cores and mixed Au–In oxide shells. Whereas bare ITO electrodes show very low activity for the detection of HQ, their modification with Au–In core–shell nanoparticles induces a pronounced shift of the oxidation peak to lower potentials, i.e., facilitated oxidation. The response of the different electrodes was correlated with the initial composition of the bimetallic nanoparticle cores, which in turn determined the amount of Au and In stabilized on the surface of the amorphous Au–In oxide shells available for the electrochemical reaction. While adding core–shell nanostructures with different compositions of the alloy core facilitates the electrocatalytic (reduction-) oxidation of HQ, the activity is highest for particles with AuIn cores (i.e., a Au:In ratio of 1). This optimal system is found to follow a single pathway, the two-electron oxidation of the quinone–hydroquinone couple, which gives rise to high oxidation peaks and is most effective in facilitating the electrode-to-analyte charge transfer and thus detection. The limits of detection (LOD) decreased when increasing the amount of Au exposed on the surface of the amorphous Au–In oxide shells. The LODs were in the range of 10–5–10–6 M and were lower than those obtained using bulk Au.2022-07-72022-07-07Research carried out in part at the Center for Functional Nanomaterials, Brookhaven National Laboratory, which is supported by the U.S. Department of Energy, Office of Basic Energy Sciences, under Contract DE-SC0012704. EB- 14, University of Valladolid (PIF-UVa) Ministerio de Economía, Industria y Competitividad – FEDER (Grant CICYT AGL2012-335

An electrochemical immunosensor based on a 4,4′-thiobisbenzenethiol self-assembled monolayer for the detection of hemagglutinin from avian influenza virus H5N1

An electrochemical immunosensor for the detection of hemagglutinin from avian influenza virus H5N1 is presented in this paper. The following steps lead up to the construction of immunosensor: (i) modification of gold electrodes with 4,4′-thiobisbenzenethiol, (ii) modification of self-assembled monolayer of 4,4′-thiobisbenzenethiol with gold colloidal nanoparticles, (iii) immobilization of single chain variable fragments of antibodies (scFv) against hemagglutinin H5 via Ssingle bondAu covalent bonds, (iv) blocking of the remaining free space with bovine serum albumin. The interactions between the scFv and hemagglutinin variants have been explored with electrochemical impedance spectroscopy in the presence of [Fe(CN)6]3−/4− as an electroactive marker. The immunosensor was able to detect two different His-tagged variants of recombinant hemagglutinin from H5N1 viruses: the short fragment (17–340 residues) of A/swan/Poland/305-135V08/2006 and the long (17–530 residues) of A/Bar-headed Goose/Qinghai/12/2005. The strongest response has been observed for the long variant with a detection limit of 0.6 pg/mL and a dynamic range from 4.0 to 20.0 pg/mL. The recombinant hemagglutinin (17–527 residues) from A/chicken/Netherlands/1/03 (H7N7), used as the negative control generated a weak response. This confirms the selectivity of the immunsensor proposed. A miniaturized version of the immunosensor, based on screen-printed gold electrodes, was tested with the same set of recombinant hemagglutinins and it achieved a linear range from 1 to 8 pg/mL with a detection limit of 0.9 pg/mL for the long fragment of hemagglutinin

An overview of recent applications of reduced graphene oxide as a basis of electroanalytical sensing platforms

© 2017 The Authors The academic literature using graphene within the field of electrochemistry is substantial. Graphene can be fabricated via a plethora of routes with each having its own unique merits (e.g. cost, fabrication time, quality and scale) and reduced graphene oxide (rGO) is more often the material of choice for electrochemical sensors and associated applications due to its ease of fabrication and ability to be mass produced on the kilogram scale. This review overviews pertinent developments in the use of rGO as the basis of electroanalytical sensors (2016–2017); guidelines for the progression of this field are also given

Thermal characteristics of yttria stabilized zirconia nanolubricants

The transition from microparticles to nanoparticles can lead to a number of changes in its properties. The objective of this work is to analyze the thermal, tribological properties of yttria stabilized zirconia nanoparticles. Nanosized yttria stabilized zir conia particles were prepared by milling the yttria stabilized zirconia (10 ftm) in a planetary ball mill equipped with vials using tungsten carbide balls. After 40 hours milled the yttria stabilized zirconia nanoparticles of sizes ranging from 70-90 nm were obtained. The phase composition and morphologies of the assynthesized particles were characterized by energy dispersive X-ray analysis, scanning electron microscope, transmission electron microscope, thermogravimetric analysis and differential scanning calorimeter, and the images of the same were obtained. From TG-DSC analysis it was confirmed that, the yttria stabilized zirconia nanoparticles were heat stable under different thermal conditions which is due to the addition of yttria to pure zirconia. Due to this property of yttria stabilized zirconia nanoparticles, it can be widely used in high transfer application such as lubricant additives. The heat transfer properties of automotive engine lubricants were determined by utilization of measured thermal conductivity, viscosity index, density, flash point, fire point and pour point revealed that lubricants with additive constituents have a significant effect on the resultant heat transfer characteristics of the lubricants

Electrochemical Detection of Furaltadone Antibiotic Drug by the Rare Earth Metal Tungstate Decorated Screen Printed Carbon Electrode

Furaltadone (FLD) is an antibiotic drug that is widely treated for coccidiosis, intestinal infection, and turkey blackhead. Moreover, excessive use of FLD may have some negative consequences for humans and domestic animals. Therefore, practical, sensitive, selective, and facile detection of FLD is still needed. In this exploration, a Eu2(WO4)3-nanoparticles-modified screen-printed carbon electrode was developed for the low-level detection of FLD. Hydrothermal techniques were used effectively to prepare the Eu2(WO4)3 complex. Scanning electron microscopy and X-ray diffraction investigations were used to confirm the Eu2(WO4)3. The results revealed that the Eu2(WO4)3 was well formed, crystalline, and uniformly distributed. Furthermore, the electrochemical behavior of the SPCE/Eu2(WO4) electrode was examined by differential pulse voltammetry and cyclic voltammetry studies. The SPCE/Eu2(WO4) electrode demonstrated improved electrocatalytic activity in the detection of FLD with a detection limit of 97 µM (S/N = 3), linear range of 10 nM to 300 µM, and sensitivity of 2.1335 µA µM−1 cm−2. The SPCE/Eu2(WO4) electrode detected FLD in the presence of 500-fold excess concentrations of other interfering pollutant ions. The practical feasibility of the SPCE/Eu2(WO4) electrode was tested on different antibiotic medicines and showed adequate recovery. Moreover, the SPCE/Eu2(WO4) electrode shows appreciable repeatability, high stability, and reproducibility

Fabrication of Carbon Nanofiber Incorporated with CuWO₄ for Sensitive Electrochemical Detection of 4-Nitrotoluene in Water Samples

In the current work, copper tungsten oxide (CuWO4) nanoparticles are incorporated with carbon nanofiber (CNF) to form CNF/CuWO4 nanocomposite through a facile hydrothermal method. The prepared CNF/CuWO4 composite was applied to the electrochemical detection of hazardous organic pollutants of 4-nitrotoluene (4-NT). The well-defined CNF/CuWO4 nanocomposite is used as a modifier of glassy carbon electrode (GCE) to form CuWO4/CNF/GCE electrode for the detection of 4-NT. The physicochemical properties of CNF, CuWO4, and CNF/CuWO4 nanocomposite were examined by various characterization techniques, such as X-ray diffraction studies, field emission scanning electron microscopy, EDX-energy dispersive X-ray microanalysis, and high-resolution transmission electron microscopy. The electrochemical detection of 4-NT was evaluated using cyclic voltammetry (CV) the differential pulse voltammetry detection technique (DPV). The aforementioned CNF, CuWO4, and CNF/CuWO4 materials have better crystallinity with porous nature. The prepared CNF/CuWO4 nanocomposite has better electrocatalytic ability compared to other materials such as CNF, and CuWO4. The CuWO4/CNF/GCE electrode exhibited remarkable sensitivity of 7.258 μA μM−1 cm−2, a low limit of detection of 86.16 nM, and a long linear range of 0.2–100 μM. The CuWO4/CNF/GCE electrode exhibited distinguished selectivity, acceptable stability of about 90%, and well reproducibility. Meanwhile, the GCE/CNF/CuWO4 electrode has been applied to real sample analysis with better recovery results of 91.51 to 97.10%

Synthesis and pharmacological evaluation of some benzylidene-4-nitroanilines

A number of nine benzylidene-4-nitroanilines were synthesized by condensation method. The formation of the substituted (E)-N-benzylidene-4-nitrobenzenamines has been confirmed from their physical and Ultra-Violet, Infra-Red, NMR spectral data. The evaluation of antimicrobial screening of substituted (E)-N-benzylidene-4-nitrobenzenamines was conducted by using standard Bauer-Kirby method. Three gram-positive microbes namely Bacillus subtilis, Micrococcus luteus and Staphylococcus aureus, and two gram-negative microbes, Escherichia coli and Pseudomonas aeruginosa, were used for the antibacterial evaluation. The antifungal activities against Aspergillus niger and Penicilium scup fungal species were also performed. A good antibacterial effect has been possessed by some of the substituted (E)-N-benzylidene-4-nitrobenzenamines on the microorganisms utilized in the present stud