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Chrysin and baicalein are the major flavonoids found in oroxylum indicum, an essential herb in traditional Chinese medicine (TCM). Owing to their similar characteristics and physiochemical property, it is a great challenge to detect both of them simultaneously. In this work, tantalum oxide (Ta 2 O 5 ) particles and chitosan modified carbon paste electrode (Ta 2 O 5 -CTS-CPE) was prepared and characterized by scanning electron microscope (SEM), X-ray diffraction spectroscopy (XRD), Fourier transform infrared spectroscopy (FTIR), cyclic voltammetry (CV) and electrochemical impedance spectrum(EIS). Under the optimum conditions, the prepared Ta 2 O 5 -CTS-CPE exhibited excellent electrocatalytic activity toward the oxidation of chrysin and baicalein, and it could serve as the sensor for highly sensitive and simultaneous determination both of them. The linear range is 0.08–4.0 μM for both of them, and the detection limits were determined to be 0.03 and 0.05 μM (S/N=3) for chrysin and baicalein, respectively. Furthermore, the proposed electrochemical sensor displayed high sensitivity, excellent stability and got satisfactory results in oroxylum indicum samples analysis. [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]

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]

A new graphene nanocomposite, CeO 2 -poly(diallyldimethylammonium chloride)-graphene (CeO 2 -PDDA-GR), was prepared by an easy and low-cost hydrothermal method. The images of transmission electron microscopy (TEM) showed that well-shaped CeO 2 nanoparticles distributed more uniformly on the GR sheets. Based on the CeO 2 -PDDA-GR composites modified glassy carbon electrode, the electrochemical properties of eriocitrin were investigated in detail and a sensitive determination method was established synchronously. Differential pulse voltammetry (DPV) measurement revealed that the oxidation peak current increased linearly with eriocitrin concentrations in range of 1.0 × 10 − 8 mol L − 1 –1.0 × 10 − 6 mol L − 1 with detection limit of 7.0 × 10 − 10 mol L − 1 (S/N = 3). Moreover, the proposed method was used in determination of eriocitrin in lemon sample with accurate results. [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]

A sensitive electrochemical method for determination of daphnetin at reduced graphene oxide (RGO) modified glassy carbon electrode (GCE) was developed. The graphene nanosheets were simply directly deposited onto a GCE surface through cyclic voltammetric reduction of graphene oxide colloidal solution. The redox character of daphnetin at ERGO/GCE was studied systematically and some dynamic parameters were calculated for the first time. The electroanalytical method for determination of daphnetin was established by differential pulse voltammograms (DPV). Under optimum conditions, the response peak currents were linear related with daphnetin concentrations in the range of 5.0 × 10 −8 to 2.0 × 10 −6 mol L −1 with a detection limit of 3.0 × 10 −8 mol L −1 . Therefore, the high sensitivity for daphnetin sensing at the proposed electrode was achieved, which was attributed to the introduced graphene films modified on GCE. Additionally, the proposed method could also be used to detect daphnetin in the medicinal capsules and Chinese medicinal herb Zushima with satisfactory results. [ABSTRACT FROM AUTHOR]