A deep eutectic solvent-assisted electrochemical synthesis of TGA capped CdSe@Cu2Se core-shell quantum dots on the graphene-modified electrode as a catalytic platform for the determination of pyrazinamide.

A two-step and fast electrochemical approach for the synthesis of CdSe@ Cu2Se core-shell quantum dots is applied in the mixture of ethylene glycol-based deep eutectic solvent and 5% water as a green media to modify the graphene film-coated glassy carbon electrode for fabricating a sensitive surface. The quantum dots particles were systematically characterized by Energy-dispersive X-ray spectroscopy (EDS), scanning electron microscopy (SEM), X-ray diffraction (XRD), FT-IR spectroscopy, UV-visible and Fluorescence emission spectroscopy, transmission electron microscopy (TEM) and cyclic voltammetry (CV) techniques. The results show the existence of a second-order chemical reaction after occurring the electron transfer reaction for pyrazinamide. The CdSe@Cu2Se modified graphene-coated glassy carbon electrode was successfully used for the determination of pyrazinamide by differential pulse voltammetry method under the optimized conditions (pH = 2) in the range of 0.4-10 µM with a corresponding detection limit of 0.37 µM. The proposed modified sensor demonstrated high selectivity, reproducibility, stability in the pharmaceutical tablets, urine, and human blood serum and high recoveries in the range of 97.9-101.9% were obtained.

Synthesis of dendritic silver nanostructures supported by graphene nanosheets and its application for highly sensitive detection of diazepam.

In this paper, preparation, characterization and application of a new sensor for fast and simple determination of trace amount of diazepam were described. This sensor is based on Ag nanodendrimers (AgNDs) supported by graphene nanosheets modified glassy carbon electrode (GNs/GCE). The AgNDs were directly electrodeposited on the surface of electrode via potentiostatic method without using any templates, surfactants, or stabilizers. The structure of the synthesized AgNDs/GNs was characterized by scanning electron microscopy (SEM), energy dispersive X-ray (EDX) analysis, X-ray diffraction (XRD) and electrochemical impedance spectroscopy (EIS) techniques. The nanodendrimers with tree-like and hierarchical structures have a fascinating structure for fabrication of effective electrocatalysts. The experimental results confirmed that AgNDs/GNs/GC electrode has good electrocatalytic activity toward the reduction of diazepam. A low detection limit of 8.56×10(-8)M and a wide linear detection range of 1.0×10(-7) to 1.0×10(-6)M and 1.0×10(-6) to 20×10(-6)M were achieved via differential pulse voltammetry (DPV). The proposed electrode displayed excellent repeatability and long-term stability and it was satisfactorily used for determination of diazepam in real samples (commercially tablet, injection and human blood plasma) with high recovery.