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Preparation of MnS/Co 3 S 4 ErGO/GCE and schematic diagram of its electrochemical response to DA. This protocol used a two-step ion exchange method to prepare MnS/Co 3 S 4 heterostructures, with self-made cobalt chloride bicarbonate (CO (CO 3) 0.35 C 0.20 (OH) 1.10) as the precursor, sodium disulfide monohydrate as the sulfur source, and manganese chloride as the manganese source. The obtained MnS/Co 3 S 4 -ErGO was modified on a glassy carbon electrode, exhibiting electrochemically ultrasensitive ability for the redox reaction of DA determination at nanomolar concentration. [Display omitted] • An ultrasensitive DA determination sensor at nanomolar level is presented. • High selectivity, selective and good reproducibility of the sensor is obtained. • Good linear concentration ranges of DA with low LOD (2.0 nM) is observed. • The sensor is successfully applied to the detection of DA in real samples. An ultrasensitive and selective electrochemical sensor has been constructed for the quantitative assay of dopamine (DA) based on hollow tubular manganese-cobalt sulfide (MnS/Co 3 S 4) hybrids embedded on electrochemically reduced graphene oxide (ErGO). The MnS/Co 3 S 4 heterostructures were created by two-step ion exchange method, of which Co 9 S 8 with hollow tubular structures was fabricated by solvothermal method using the self-made cobalt chloride carbonate hydroxide (CO(CO 3) 0.35 Cl 0.20 (OH) 1.10) as precursor and sodium disulfide monohydrate as sulfur source and manganese chloride as manganese source. The MnS/Co 3 S 4 -ErGO/GCE could exhibit strong catalytic ability for the redox reaction of DA. Under the optimal conditions, the developed sensor exhibits a wide linear response for DA ranging from 6.0 nM to 20.0 μM by second-order derivative linear sweep voltammetry (SDLSV), with a detection limit of 2.0 nM. In addition, the developed method exhibited high sensitivity and selectivity, good reproducibility and low-cost. It is a very promising analytical method for the determination of DA in pharmaceutical and biological samples. [ABSTRACT FROM AUTHOR]

A bismuth oxide-carboxylated multi-walled carbon nanotube/glassy carbon electrode (Bi 2 O 3 -CMWCNTs/GCE) was prepared for the detection of the flavonoid drug baicalein. The Bi 2 O 3 was grown on the surface of CMWCNTs by in-situ synthesis, and a simple, and efficient Bi 2 O 3 -CMWCNTs composite was prepared. The materials were characterized by XRD, SEM and EDS. CV and EIS techniques were used to study the electrochemical sensing performance of the composite electrode surface. The electrochemical performance and optimal detection conditions of baicalein on Bi 2 O 3 -CMWCNTs/GCE were investigated by LSV. The oxidation peak current of baicalein has a linear relationship with its concentration in the range of 0.01–15 μmol·L−1, with a detection limit of 2.0 nmol·L−1. The method is both stable and effective, and was successfully used for determination of baicalein in human urine and the Chinese herb Oroxylum indicum. It shows that the in situ synthesized materials have more stable characteristics, and have promising applications in the detection of flavonoid drugs. [Display omitted] • A novel sensor Bi 2 O 3 -CMWCNTs/GCE was prepared which for the stable determination of baicalein. • High selectivity, repeatability and reproducibility of the sensor were obtained. • Good linear concentration ranges of baicalein with low LOD (2.0 nM) were observed. • The sensor was successfully applied to the detection of baicalein in real samples. [ABSTRACT FROM AUTHOR]

This review comprehensively discusses the performance of various electrochemical sensors using different detection recognition methods, based on nanomaterials, MIPs, aptamer, etc. The portable electrochemical sensors using smartphone, USB and disk are summarized in detail. The future research direction and challenges of using portable devices for the detection of mycotoxins are highlighted. [Display omitted] • Recent progress in electrochemical sensors is summarized for various mycotoxins detection in food. • The main electrochemical recognition methods for mycotoxins detection are discussed. • On-site portable electrochemical devices are reviewed. • Future research trends and perspectives on portable electrochemical sensors are presented. The mycotoxins commonly found in food may pose a significant threat to human health. Therefore, the development of portable electrochemical sensing chip methods is very important. In addition, due to the need to study various pollutants when conducting food analysis, which involves multiple and complex fields, the use of disposable portable sensing chips can improve detection efficiency. In this review, we have summarized the significant work on electrochemical sensors for mycotoxins detection in food samples. Although earlier reviews have covered this topic, the mechanisms and portable use of toxin detection have not yet been addressed. This paper's novelty is that it has reviewed recent advances in various electrochemical sensors and portable applications, for mycotoxins detection. This provides a new perspective on future trends in the development of portable electrochemical sensors. [ABSTRACT FROM AUTHOR]

A bismuth oxide- nitrogen doped reduced graphene oxide/glassy carbon electrode (Bi 2 O 3 -NRGO/GCE) was prepared for the detection of the flavonoid drug chrysin in pharmaceutical capsules, for the first time. [Display omitted] • Bi 2 O 3 nanosheet materials were synthesized by a hydrothermal method. • Bi 2 O 3 -NRGO/GCE were used to construct sensors for the detection of chrysin. • A linear range (0.01–10 μM) and LOD (2 nM) for chrysin detection were achieved. • The sensors were used for the ultrasensitive determination of chrysin in pharmaceutical preparations. A bismuth oxide- nitrogen doped reduced graphene oxide/glassy carbon electrode (Bi 2 O 3 -NRGO/GCE) was prepared for the detection of the flavonoid drug chrysin in pharmaceutical capsules, for the first time. Bi 2 O 3 nanosheets synthesized by a hydrothermal method, were ultrasonically mixed with NRGO, and a simple and efficient Bi 2 O 3 -NRGO/GCE composite was prepared. The composites were characterized by various methods. Cyclic voltammetry and electrochemical impedance techniques were used to study the electrochemical sensing performance of the composites-modified electrode surface. The electrochemical performance and optimal detection conditions of chrysin on Bi 2 O 3 -NRGO/GCE were investigated by differential pulse voltammetry (DPV). The oxidation peak current of chrysin has a linear relationship with its concentration, in the range of 0.01–10 μM, with a detection limit of 2.0 nM. Bi 2 O 3 -NRGO/GCE also has good selectivity for chrysin, which is not interfered with by common inorganic salts and common organic substances, or by structurally similar substances. The composite electrode also has good repeatability, reproducibility and stability. It shows that utilizing Bi 2 O 3 and NRGO binary complexes modified electrodes for ultrasensitive chrysin sensing is a simple and convenient detection method, with promising applicability in the development of pharmaceutical component sensing technology. [ABSTRACT FROM AUTHOR]

In this paper, a sensitive electrochemical sensor based on MnO 2 nanoparticles functionalized carboxylated multi-walled carbon nanotubes (MnO 2 -c-MWCNTs) was prepared for the determination of curcumin. The synthesized materials have been fully characterized by instruments, such as X-ray diffraction (XRD), scanning electron microscopy (SEM), cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS). The electrochemical behavior of curcumin on the MnO 2 -c-MWCNTs modified glassy carbon electrode (MnO 2 -c-MWCNTs/GCE) was investigated in detail by CV and chronocoulometry (CC). The electrochemical reaction mechanism of curcumin on the modified electrode was also discussed. In 0.1 M H 2 SO 4 solution, the peak current showed a good linear dependence on curcumin concentration in the range of 0.01–1 μM and 1–80 μM, The method has high sensitivity (3.30 μA μM−1 cm−1), and the detection limit is 6.0 nM. At the same time, the MnO 2 -c-MWCNTs/GCE has good anti-interference ability and stability. In addition, the sensor was used for the accurate and rapid determination of curcumin in commercial food samples, which shows its good potential for practical application. [Display omitted] • A novel sensor MnO 2 -c-MWCNTs/GCE was prepared which for the stable determination of curcumin. • High selectivity, repeatability and reproducibility of the sensor were obtained. • Good linear concentration ranges of 0.01–1 μM and 1–80 μM curcumin with low LOD (6.0 nM) were observed. • The sensor was successfully applied to the detection of curcumin in nanomolarity in real samples. [ABSTRACT FROM AUTHOR]