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A novel electrochemically activated doped Ta2O5 particles modified carbon paste electrode (EA-Ta2O5-CPE) was prepared and applied for selective and sensitive determination of chrysin. X-ray diffraction (XRD), scanning electron microscopy (SEM), electrochemical impedance spectroscopy (EIS) techniques and cyclic voltammetry (CV) were used to characterize the Ta2O5 particles and investigate the electrochemical response of the sensor. Compared with bare CPE, the doped Ta2O5 modified electrode got much more porous by electrochemical treatment and exhibited larger effective surface area, more reactive site and excellent electrochemical catalytic activity toward the oxidation of chrysin. Under optimum conditions by LSV, the oxidation peak currents responded to chrysin linearly over a concentration range from 5.0×10−8 to 7.0×10−6 mol L−1 with a detection limit of 2.0×10−8 mol L−1 (5.08 ng mL−1). The fabricated sensor showed anti-interference ability against the biological common interferents (i.e. baicalein, baicalin) and provided to be reliable for the determination of chrysin in Chinese medicinal herb Oroxylum indicum and chrysin capsules samples with satisfactory results. [ABSTRACT FROM AUTHOR]

[Display omitted] • NiCoMnS/rGO was synthesized by one-step hydrothermal method. • NiCoMnS/rGO nanocomposite showed good peroxidase-like activity. • NiCoMnS/rGO/GCE can catalyze H 2 O 2 reduction and glucose oxidation. It is attractive to develop non-noble-metal nanomaterials with large surface area and good conductivity as a high-active catalyst electrode for molecular detection in electrochemical sensors. In this work, we successfully fabricated NiCoMnS/rGO by one-step hydrothermal method, which showed good peroxidase-like activity in an acidic environment. The NiCoMnS/rGO modified electrode exhibited excellent enzyme-free electrochemical catalysis performance for hydrogen peroxide (H 2 O 2) reduction in acidic solutions and glucose oxidation in alkaline solutions. For the detection of H 2 O 2 , this electrochemical sensor displayed a wide linear range from 10.0 μM to 7.5 mM with a low limit of detection of 1.1 μM. As for glucose, it also showed a wide linear range from 50.0 μM to 1.3 mM with a low limit of detection of 1.0 μM. Moreover, it had good stability and reproducibility. It was also used for the determination of H 2 O 2 and glucose in real samples. This nanomaterial held great promise as an enzyme-free sensing platform toward H 2 O 2 and glucose detection. [ABSTRACT FROM AUTHOR]

A new type of voltammetric sensor, Langmuir-Blodgett (LB) film of multi-walled carbon nanotubes (MWCNTs) perpendicularly modified glassy carbon electrode (GCE), was prepared and applied in determination of methylparaben. Based on the excellent electrochemical property of vertical MWCNTs on the GCE (MWCNTs-LB/GCE), a sensitive voltammetric method for determination of methylparaben was erected with liner range from 1 × 10 −6 mol L −1 to 8 × 10 −5 mol L −1 and detection limit of 4 × 10 −7 mol L −1 . The electrochemical characters of MWCNTs-LB/GCE were investigated in detail and the reaction mechanism of methylparaben was discussed. Meanwhile, cosmetic samples were analyzed using proposed method and the results obtained were well satisfactory. [ABSTRACT FROM AUTHOR]

Graphical abstract Highlights • A new MOF-5@PDDA-rGO-Ni nanostructure is successfully synthetized for the first time. • MOF-5@PDDA-rGO-Ni/GCE sensor exercises an extraordinary response towards echinacoside as the first detection. • The ratiometric electrochemical sensor devotes a higher accuracy and repeatability than MOF-5@PDDA-rGO-Ni/GCE that affords. • The reliability and stability of the recommendable assay are fairly validated in real sample sliced Cistanche analysis. Abstract In this work, a brand new nanocomplex (denoted as MOF-5@PDDA-rGO-Ni) is elaborately designed and successfully synthesized meaning the in-situ assembly of porous-morphology Zn-based MOFs (MOF-5) onto the as-prepared PDDA-rGO-Ni (PGN for short) nanocomposites. When this nanocomplex contributes to construct the electrochemical sensor (MOF-5@PGN/GCE), it presents a highly-sensitive response towards echinacoside, and the first measurement for echinacoside by electrochemistry accordingly evolves forward. The crystallization processes are investigated by FT-IR instrument and XRD analysis, as well as micro-morphology of modified materials is visible upon SEM and TEM. Adorably, a novel ratiometric sensor was progressively fabricated by encapsulating methylene blue (MB) molecules into cubic MOF-5 framewoks (MB encased MOF-5@PGN/GCE), and apart from assisting in establishing the analysis method with extreme accuracy and favorable practicality, it dose devote a wider linear scale and a lower detection limit than that MOF-5@PGN/GCE has given out. Drawn from the developed calibration curve using differential pulse voltammetry (DPV) technique, the peak intensity ratio (I Ech /I MB) varies linearly with increased echinacoside concentration in the range of 3.0 × 10−8– 1.0 × 10−6 mol L−1 with limit of detection (LOD) reaching 1.0 × 10−8 mol L−1 (S/N = 3). Additionally, the proposed assay method has been employed to detect echinacoside in real sample sliced cistanche with satisfactory results. [ABSTRACT FROM AUTHOR]

The nanocomposite of ruthenium oxide (RuO 2 ) loaded on Poly-(dimethyldiallylammonium chloride) (PDDA) functionalized reduced graphene oxide (RuO 2 -PDDA-rGO) was synthesized based on a one-step method. Based on the RuO 2 -PDDA-rGO modified glassy carbon electrode (GCE), a new electrochemical sensor (RuO 2 -PDDA-rGO/GCE) was fabricated and used in detection of baicalein for the first time. Compared with other reported electrochemical sensors for the detection of baicalein, the prepared RuO 2 -PDDA-rGO/GCE had a wider linear range (2–400 nM) and lower detection limit (0.6 nM, S/N = 3). The other advantages were the excellent repeatability of proposed method and good stability of prepared sensor. [ABSTRACT FROM AUTHOR]

In this paper, a simple, low cost, highly sensitive voltammetric method for determination of tetrahydropalmatine was described, which was based on a new electrochemical sensor, poly (L-glutamic acid) functionalized electrochemical reduction graphene oxide modified glassy carbon electrode. The electrochemical behavior of tetrahydropalmatine was investigated in detail and some dynamic parameters of electrode process were calculated for the first time. Due to large surface area and good conductivity of proposed sensor, a wider linear range (3.0×10 −7 –2.0×10 −5 mol L −1 ) and lower detection limit (1.0×10 −7 mol L −1 ) were achieved for determination of tetrahydropalmatine. Meanwhile, the proposed method was used in determination of tetrahydropalmatine in Rhizoma Corydalis with well results. [ABSTRACT FROM AUTHOR]

A novel voltammetric sensor was constructed by simple dripping single-walled carbon nanotubes (SWCNTs) on to the glass carbon electrode (GCE) firstly and electro-polymerizing l -Citrulline film subsequently. The resulting poly( l -Citrulline)/SWCNTs/GCE showed a significant voltammetric response to picroside II due to the synergistic effect of SWCNTs and poly( l -Citrulline) film. The first electroanalytical method of picroside II was proposed with detection linear range from 8.0×10 −8 to 5.0×10 −6 mol L −1 and a detection limit of 3×10 −8 mol L −1 .The high sensitivity, selectivity and long-term stability made the sensor suitable for the determination of picroside II. Moreover, based on the systematically investigation and some kinetics parameters calculated in the experimentation, the reaction mechanism of picroside II at the poly( l -Citrulline)/SWCNTs modified GCE was obtained reliably. Lastly, the proposed sensor was used for the determination of picroside II in real sample with satisfactory results. This work promoted the potential applications of amino acid materials and SWCNTs in electro-chemical sensors. [ABSTRACT FROM AUTHOR]

A simple, inexpensive and highly sensitive voltammetric method for the determination of tectoridin was developed using a poly( l -Arginine) modified electrode. The redox character of tectoridin at proposed electrode was studied systematically and some dynamic parameters were calculated for the first time. A reasonable reaction mechanism of tectoridin on the poly( l -Arginine)/GCE was also dicussed and proposed, which could be a reference for the pharmacological action of tectoridin in clinical study. And the electroanalytical method for determination of tectoridin was established by differential pulse voltammograms (DPV). Under optimum conditions, the response peak currents were linear relationship with tectoridin concentrations in the range of 5.0×10 −8 –2.0×10 −6 mol L −1 with a detection limit of 4.0×10 −8 mol L −1 . Therefore, the high sensitivity for tectoridin sensing at the proposed electrode was achieved, and the proposed method could also be used to detect tectoridin in the Chinese medicinal herb Blackberrylily with satisfactory results. [ABSTRACT FROM AUTHOR]

Here, we developed a homogeneous electrochemical biosensor for the sensitive determination of antibiotic by the CHA reaction and the consecutive adenine mediated probe fixation. The binding of target to the target recognition sequences in the triple-helix DNA can release the trigger. It can initiate the catalytic hairpin assembly (CHA) to generate lots of mimic targets, which were labeled with electroactive substance ferrocene (Fc). Because the generated mimic target has consecutive sequence of adenines (PolyA), they can be self-assembled on the AuNPs modified electrode and finally realize electrochemical detection. Under optimal conditions, this developed biosensor achieved a satisfactory limit of detection of 0.089 nM (S/N = 3) and a linear range from 0.1 nM to 100 nM for sensitive detection of oxytetracycline with good specificity. The whole process is carried out in homogeneous solution, not only realizes signal amplification, but also avoids the complex modification process of electrode surface. Compared with some reported electrochemical sensors, the method is easier to operate and has good precision. [Display omitted] • CHA and signal amplification were triggered by target. • The transformation process between the target and the Fc labeled mimic target was accomplished in homogeneous system. • Mimic targets were self-assembled on the electrode surface by poly adenine to generate electrochemical signal. [ABSTRACT FROM AUTHOR]

A new voltammetric sensor for simultaneous detection of bisphenol A and bisphenol S with high sensitivity has been constructed based on a three-component composite modified glassy carbon electrode. The three-component composite used herein is composed of AuAgPt ternary alloy nanocrystals (AuAgPt), porous β-cyclodextrin polymer (PCD) and oxide graphene (GO), abbreviated as AuAgPt-PCD-GO. The obtained composites were characterized by transmission electron microscopy (TEM), scanning electron microscopy (SEM), and scanning transmission electron microscopy (STEM). The proposed modified electrode showed excellent electrochemical response to bisphenol A and bisphenol S simultaneously. Under optimal experiment conditions, the response linear ranges for bisphenol A and bisphenol S are from 6 nM to 4000 nM and 8 nM–8000 nM with detection limits of 2 nM and 2.67 nM (S/N = 3), respectively. Furthermore, this electroanalytical sensor could also be successfully applied to real sample analysis with satisfactory results. Image 1 • The three-component composite material AuAgPt-PCD-GO was designed to construct a novel electrochemical sensor for simultaneous BPA and BPS assay. • The possible electrochemical oxidation mechanism of BPA and BPS on the modified electrode was deduced. • The proposed sensor can be used for real sample assay with satisfactory results. [ABSTRACT FROM AUTHOR]