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This paper reports a simple and sensitive approach for the determination of troxerutin using a zirconia oxide/graphene doped carbon paste electrode (ZrO2/Gr-CPE). Highly uniform and stable ZrO2 nanoparticles were deposited on Gr sheet via a rapid route. By introducing this nanocomposite into carbon paste electrode, the obtained electrochemical sensor showed sensitive response for troxerutin. Based on this sensor, an accurate sensitive analytical method for troxerutin was established with a linear range from 2 × 10−9 to 3 × 10−7 mol L−1 and a detection limit 6 × 10−10 mol L−1. Meanwhile, the electrochemical properties of troxerutin were investigated in detail. Finally, the proposed method was applied to the analysis of real-life samples with satisfactory results. [ABSTRACT FROM AUTHOR]

A new and sensitive electrochemical sensor for rutin determination was developed based on cetyltrimethylammonium chloride (CTAC) functionalized graphene (Gr) and palladium nanoparticles (Pd) (CTAC-Gr-PdNPs) composite. Rutin displayed remarkably increased electrochemical activity on the CTAC-Gr-PdNPs composite modified electrode due to the synergistic effect of the large surface area and electrocatalytic activity of both Gr and Pd nanoparticles, which offers the feasibility for highly sensitive determination of rutin via electrochemistry. Under the optimal experimental conditions, the oxidation peak current of rutin was proportional to its concentration in the range of 2.0 × 10−8–1.0 × 10−6 mol L−1, and the limit of detection (LOD) was 5 nM (S/N = 3). The developed method was successfully applied to determine rutin in pharmaceuticals with satisfactory recoveries, which shows that the fabricated sensor has potential in pharmaceutical analysis. [ABSTRACT FROM AUTHOR]

A simple, highly sensitive voltammetric method for the determination of urapidil at poly(sodium4-styrenesulfonate) functionalized graphene-modified electrode (PSS-Gr/GCE) was described. Based on the PSS-Gr composites-modified glassy carbon electrode as a simple voltammetric sensor, it exhibited good conductivity and high sensitivity to urapidil. Under the optimize condition, a good linear relationship was obtained between peak currents and urapidil concentrations in the wider range of 2.0 × 10−9–8.0 × 10−8 mol L−1 and 2.0 × 10−7–2.0 × 10−5 mol L−1 with detection limit of 8 × 10−10 mol L−1 (S/N = 3). Based on the high sensitivity and good selectivity of the proposed electrode, the proposed method could apply to the detect of urapidil in urapidil sustained release tablets with satisfactory results. [ABSTRACT FROM AUTHOR]

A new voltammetric sensor, based on multi-walled carbon nanotubes (MWCNTs) composite poly(aspartic acid) film modified glassy carbon electrode, was fabricated and used for determination of pesticide imidacloprid. The synergistic effect of MWCNTs and the polymer resulted in a significantly improved electrochemical response (in terms of sensitivity, accuracy and analytical range) towards imidacloprid. Under selective conditions, the determination linear range was from 1.53 × 10−5 g L−1up to 1.53 × 10−2 g L−1with a detection limit of 1.15 × 10−5 g L−1(S/N = 3). The sensor also had an easily renewable surface, good fabrication reproducibility, and inherent stability. Moreover, satisfactory results were obtained with complex samples and demonstrate the reliability of the proposed method. [ABSTRACT FROM PUBLISHER]

Six new coordination complexes, [Cd(η2-OOCCH=(CH3)CFc)2(bix)]2·(CH3OH)0.5(1), [Zn(η2-OOCCH=(CH3)CFc)(η1-OOCCH=(CH3)CFc)(bix)]2·(H2O)0.5(2), [Zn(η2-OOCCH=(CH3)CFc)2(pbbm)]2·(CH3OH)2(3), {[Mn(η1-OOCCH=(CH3)CFc)2(bbbm)(H2O)2]·(CH3OH)3}n(4), {[Cd(η1-OOCCH=(CH3)CFc)2(bbbm)]·(CH3OH)2}n(5), and [Cd(η2-OOCCH=(CH3)CFc)2(pmbbm)]n(6) {Fc = (η5-C5H4)Fe(η5-C5H4), bix = 1,4[bis(imidazol-1-ylmethyl)benzene], pbbm = 1,1′-[(1,4-propanediyl)bis-1H-benzimidazole], bbbm = 1,1′-[(1,4-butanediyl)bis-1H-benzimidazole)], pmbbm = 1,1′-[(1,4-pentanediyl)bis-1H-benzimidazole]}, were prepared and characterized. X-ray crystallographic analysis reveals that1–3are dimers bridged by bix and pbbm. Complexes4–6are one-dimensional (1-D) structures bridged by bbbm and pmbbm, respectively. Variousπ–πinteractions were discovered in1–6that make significant contributions to molecular self-assembly. Solution differential pulse voltammetry of1–6indicates that the half-wave potentials of the ferrocenyl moieties in these complexes shift to positive potential compared with that of 3-ferrocenyl-2-crotonic acid. [ABSTRACT FROM AUTHOR]

A new voltammetric sensor, based on a new p-tert-butylcalix[4]arene derivative (TCAD) modified glassy carbon electrode (GCE) using Langmuir–Blodgett (LB) technique, was designed successfully and used for recognition and determination of Ag+. The π - A isotherms suggested that the monolayer of TCAD can coordinate with Ag+ at the air–water surface. Under the optimum experimental conditions, this voltammetric sensor shows a linear voltammetric response for Ag+ in the range of 1.0 × 10−8 ∼ 6.0 × 10−6 mol L−1 with detection limit 5.0 × 10−9 mol L−1. The high sensitivity, selectivity, and stability of this LB film modified electrode also demonstrate its practical application for a simple, rapid and economical determination of Ag+ in water sample. [ABSTRACT FROM AUTHOR]

A novel voltammetric sensor using multi-wall carbon nanotubes (MWNTs) coupled with Nafion modified glassy carbon electrode (GCE) was developed for the detection of methylparaben (MP). The sensor exhibited good electrocatalytic activity toward the oxidation of MP in the phosphate buffer solution (PBS, pH 6.5). It displayed good sensitivity, repeatability, reproducibility, and long-term stability. Under the optimized conditions, the anodic peak current was linear with the concentration of MP in the range of 3 × 10−6 mol L−1 to 1 × 10−4 mol L−1. The detection limit was 1 × 10−6 mol L−1. The proposed method was successfully applied to determine MP in cosmetics with satisfactory results. [ABSTRACT FROM AUTHOR]

Using the sol-gel method, p-tert-butyl-calix[4]arene sol-gel coating capillary (BCx4-SGCC) was prepared and characterized by infrared spectroscopy and electroosmotic flow. Their separation performance was investigated by using benzenediol positional isomers and axially chiral binaphthyl derivative 2-amino-2'-hydroxy-1,1'-binaphthyl (BHA) without symmetric carbon center as probes. The migration behaviors of these analytes on the BCx4-SGCC with the open tubular capillary electrochromatography separation mode were influenced by the supermolecular interaction between calixarene and analytes. The results from the quantum chemistry calculation using DFT-B3LYP/STO-3G** base set were consistent with the migration behaviors of benzenediol and BHA. [ABSTRACT FROM AUTHOR]

The study on interaction of dsDNA with the combination of methotrexate and emodin demonstrated that emodin and methotrexate can form intermolecular hydrogen bonds that enhance the anticancer effect of methotrexate and decrease the side effects. The results show that a combination of synthetic and herbal medicines in treating cancer is very effective and can be used to select other effective combination uses of antitumor drugs. At the same time, according to different interaction models of methotrexate with dsDNA and ssDNA, methotrexate can be used to discriminate between dsDNA and ssDNA in a DNA biosensor as hybridization indicator. [ABSTRACT FROM AUTHOR]