A new electrochemical sensor, based on NdFeO3 nanoparticles as electrocatalytic material, was proposed here for the detection of dopamine (DA). NdFeO3 nanoparticles were first synthesized by a simple thermal treatment method and subsequent annealing at high temperature (700 °C). The prepared electrocatalytic material has been characterized in detail by SEM-EDX, XRD, and Raman techniques. Characterization results display its sheet-like morphology, constituted by a porous network of very small orthorhombic NdFeO3 nanoparticles. NdFeO3 electrocatalytic material was then used to modify the working electrode of screen-printed carbon electrodes (SPCEs). Electrochemical tests demonstrated that NdFeO3– modified screen-printed carbon electrode (NdFeO3/SPCE) exhibited a remarkable enhancement of the dopamine electrooxidation, compared to the bare SPCE one. The analytical performance of the developed sensor has been evaluated for the detection of this analyte by means of the square-wave voltammetry (SWV) technique. The modified electrode showed two linear concentration ranges, from 0.5 to 100 μM and 150 to 400 μM, respectively, a limit of detection (LOD) of 0.27 μM (at S/N = 3), and good reproducibility, stability, and selectivity. Additionally, we also report an attempt made to propose the modified sensor for the simultaneous detection of dopamine and uric acid (UA). The procedure was also applied for the determination of dopamine in spiked real samples. So, this paper reports for the first time the use of a modified NdFeO3 screen-printed electrode for developing an electrochemical sensor for the quantification of important biomolecules.
Digital watermarking is the process of embedding information into a digital signal in a way that is difficult to remove. In this article a secure quantum watermarking using entanglement swapping is proposed. Here the entanglement swapping is employed to build up a hidden layer of secure message under the conventional first layer of secure information sequence. In this protocol by insuring the security of transmission of the first layer of information sequence the security of the hidden secret messages is also proved to be reliable regardless of whether the hidden channel has been detected or not. 相似文献
Room temperature 1-butyl-3-methylimidazolium tetraflouroborate ([BMIM][BF4]) ionic liquid was employed for dispersion of multi walled carbon nanotubes (MWCNTs) and the formation of nanocomposite on the surface of a carbon-ceramic electrode. The surface of the modified electrode was characterized using scanning electron microscopy and electrochemical impedance spectroscopy. The modified electrode exhibited excellent electrochemical activity to oxidation of dopamine (DA); whereas electro oxidation of ascorbic acid (AA) was not seen and electro oxidation of uric acid (UA) appeared at a more positive potential than DA. The multi walled carbon nanotube-ionic liquid nanocomposite modified carbon-ceramic electrode was used for the selective determination of DA in the presence of high levels of AA and UA using differential pulse voltammetry. The calibration curve for DA was linear in the range of 3.00 to 130 µM with the detection limit (S/N=3) of 0.87 µM. The present electrode was successfully applied to the determination of DA in some commercial pharmaceutical samples and human blood serum. 相似文献
In this study homogeneous powders of CuWO4 and WO3 was produced from ammonium para-tungstate (APT) and copper nitrate. Then, the product was used to prepare nano-sized W-Cu
powder. Hence, a mixture of ammonium paratungstate and copper nitrate with predetermined weight proportion was made in distilled
water, while the content of the beaker was being stirred at a certain speed to reach the desired composition of W-20 wt %
Cu. Mixture was heated to 80–100°C for 6 h. Also, pH range was adjusted at about 3–4. The mixture was then evaporated and
dried in the air. To reach W-Cu composite powder, the precursor powders burned out at 520°C for 2 h in the air to form W-Cu
oxide powder and then were ball milled and reduced in H2 atmosphere to convert it into W-Cu composite powder. The resulting powders were evaluated using scanning electron microscopy,
X-ray diffraction, thermogravimetric analysis and differential thermal analysis techniques. The results showed that homogeneous
powders of W-Cu with particle size of around 100 nm and a nearly spherical shape could be obtained by this process. Each particle
include smaller parts with size of around 20–30 nm. 相似文献
The boron atom in C22H15BO5 is O,O’-chelated by the anions in a tetrahedral geometry, with the planar five-and six-membered chelate rings being orthogonal to each other. The molecule lies on a two-fold rotation axis. The molecule is disordered with respect to another molecule in a 93:7 ratio; the treatment of the ‘whole-molecule disorder’ by employing a large number of restraints is described. Crystal data: C22H15BO5, monoclinic C2/c, a = 17.1804(5), b = 12.9409(4), c = 9.8842(3) , β = 124.832(2)o, V = 1803.82(9) 3 at –173 K. 相似文献
We report fabrication of silver nanoparticles (Ag NPs) by laser ablation technique in different concentrations of aqueous
chitosan solution. The ablation process of silver plate was carried out by using a nanosecond Q-switched Nd:YAG pulsed laser
and the characterization of Ag NPs was done by Transmission electron microscopy, UV-Vis spectroscopy, and X-ray diffraction.
UV-visible plasmon absorption spectra revealed that the formation efficiency as well as the stability of nanoparticles was
increased by addition of chitosan. On the other hand, the size decrement of nanoparticles was more remarkable in the higher
chitosan concentration. 相似文献
A mixture of guanidinium nitrate and silica sulfuric acid acts as mild and heterogeneous media for the efficient mono nitration of phenolic compounds in dichloromethane at room temperature. 相似文献
The structures of a series of spherical host-guest complexes [{MeE(PPh)(3)Li(4)·3thf}(4)(μ(4)-X)](-) (E = Al, [1X](-); E = Ga, [2X](-); E = In, [3X](-)) reveal that changing the halide ions (X = Cl, Br, or I) within their central tetrahedral Li(4) sites has negligible effect on the structural parameters. 相似文献