Search

This paper demonstrated using polyethylenimine (PEI)-functionalized graphene (Gr) incorporating tin oxide (SnO2) hybrid nanocomposite as a platform for nonenzymatic H2O2 electrochemical sensor. The results of UV-vis spectroscopy and X-ray diffraction (XRD) confirmed the simultaneous formation of tin oxide (SnO2) nanocomposite and reduction of graphene oxide (GO). Transmission electron microscopy (TEM) images showed a uniform distribution of nanometer-sized tin oxide nanoparticles on the grapheme sheets, which could be achieved using stannous chloride (SnCl2) complex instead of tin oxide as precursor. The electrochemical measurements, including cyclic voltammetry (CV) and amperometric performance (I-t), showed that the PEI-functionalized Gr supported SnO2 (SnO2-PEI-Gr) exhibited an excellent electrocatalytic activity toward the H2O2. The corresponding calibration curve of the current response showed a linear detection range of 9×10−6∼1.64×10−3 mol L−1, while the limit of detection was estimated to be 1×10−6 mol L−1. Electrochemical studies indicated that SnO2 and functionalized Gr worked synergistically for the detection of H2O2. [ABSTRACT FROM AUTHOR]

Abstract: A new and sensitive sensor for morphine, based on electrochemically reduced MWNTs-doped graphene oxide (ER-MWNTs-doped-GO) composite film modified glassy carbon electrode, was reported. Electrochemical impedance spectroscopy and scanning electron microscopy were employed to study the characteristic of the ER-MWNTs-doped-GO film. The electrochemical behaviour of morphine on this sensor was investigated in pH 4.5 phosphate buffer solution by cyclic voltammetry and linear sweep voltammetry. Significant advantages were achieved by combining the excellent conductivity of MWNTs and ER-GO with the film forming properties of GO. And some merits for response towards morphine from this sensor were showed such as wide linear range, fine selectivity and sensitivity, low detect limit and easy surface renewing. The application of the proposed method in analysis of real sample was also evaluated with good performance. [Copyright &y& Elsevier]

Cancer is one of the main diseases threatening human health in the world. Doxorubicin (DOX) is a common anti-cancer drug that can be used for chemotherapy to extend a cancer patient's life. It is our common wish that treatment process of cancer is efficient and secure. Therefore, it is of great significance to develop sensitive, rapid and accurate techniques for anti-cancer drug doxorubicin (DOX) detection. Herein, in our work, a ratiometric electrochemical sensor for DOX detection was designed, which based on MB@MWCNTs/UiO-66-NH 2 composites. The porous materials UiO-66-NH 2 magically shoulder double function in our ratiometric electrochemical strategy, which can reduce the interior error caused by the various complex materials. Specifically, on the one hand, it can be used to catalyze DOX, which can provide a great current signal to be detected, on the other hand, its special property of absorbing molecules was utilized to load materials as internal reference. Consequently, we chose methylene blue (MB) as the substance that can generate an internal reference signal, because it is a specific and stable electroactive substance. Then, we added MWCNTs as a part of the material modified on the ratiometric electrochemical platform to enhance the signal of the target due to its feature of good electrical conductivity. Under the optimized conditions, the ratiometric electrochemical sensor displayed a wide linear detection with the range from 0.1 μM to 75 μM and the limit of detection (LOD) of 0.051 μM. The applicability of this method in the analysis of actual human saliva samples has been confirmed by the results of selectivity, stability, and reproducibility tests, which was prospective in clinical application. [Display omitted] • Multiple function MOF was designed for ratiometric electrochemical detection of DOX. • The UiO-66-NH 2 /MWCNTs can bring catalytic reaction towards target to amplify the detection signal. • The multiple function MOF platform can be extended for analysis of other target. [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]

[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 novel high-sensitive electrochemical sensor with glassy carbon electrode (GCE) as support for hyperin determination is successfully designed and constructed, and the well-shaped nano-meter modified material is synthesized via a one-step and facile route. Functionalized with surfactant sodium dodecyl sulfate (SDS), Single-Walled Carbon Nanotubes (SWCNTs) are synchronously grafted with ZrO 2 nanoparticles to develop into the as-prepared nano-composite (ZrO 2 -SDS-SWCNTs). Compared to the previous reports related with hyperin detection, the linear range gets wider and detection limit (LOD) becomes lower with the aid of this novel nano-composite modified glassy carbon electrode (ZrO 2 -SDS-SWCNTs/GCE). The crystalline phases and functionalization of the preparation process has been investigated by X-ray diffraction (XRD) and Fourier transform infrared (FT-IR) instrument analysis, respectively, and the micro-morphology of related modified materials is also visibly characterized by scanning electron microscope (SEM) and transmission electron microscope (TEM). In addition, electrochemical properties of the modified materials are comparably explored by means of impedance spectroscopy (EIS) and cyclic voltammograms (CV). According to the established calibration curve under optimized condition, the peak current (Differential pulse voltammetry (DPV) signal) keeps a linear relationship with hyperin concentration in the ranges of 1.0 × 10 −9 − 3.0 × 10 −7 mol L −1 , meanwhile detection limit reaches as low as 5 × 10 −10 mol L −1 (S/N = 3). As for practical applications, the proposed sensor has also worked well on sensitive hyperin determination in real species Abelmoschus manihot. [ABSTRACT FROM AUTHOR]

In this work, reduced graphene oxide loaded flower-like bismuth subcarbonate composite (Bi 2 O 2 CO 3 -rGO) has been successfully synthesized by a facile hydrothermal method. The prepared Bi 2 O 2 CO 3 -rGO as modification composite was applied to construct voltammetric sensor for the first time. The Bi 2 O 2 CO 3 -rGO modified glassy carbon electrode (Bi 2 O 2 CO 3 -rGO/GCE) exhibited highly sensitive response to urapidil. The electrochemical behavior of urapidil was studied in detail. Under optimum conditions, a lower detection limit (1.5 × 10 −9  mol L −1 ) and wider linear range (5.0 × 10 −9  mol L −1 –4.0 × 10 −6  mol L −1 ) were achieved by the proposed sensor. Finally, the proposed method was applied to the analysis of real sample, and the results showed applicable and reliable. [ABSTRACT FROM AUTHOR]

A novel electrochemical daphnetin sensor was developed by employing a nanocomposite of calcium germanate-graphene (Ca 2 GeO 4 -GR) as an effective electrode material. In this strategy, Ca 2 GeO 4 nanowires could be uniformly distributed on the GR surface with average diameter of about 30–60 nm as exhibited by transmission electron microscopy (TEM). The fabricated sensor (Ca 2 GeO 4 -GR/GCE) exhibited excellent current response towards daphnetin with linear range of 2.0 × 10 − 8 mol L − 1 to 9.0 × 10 − 7 mol L − 1 and detection limit of 6 × 10 − 9 mol L − 1 (S/N = 3). In addition, the sensor also demonstrated strong anti-interference properties in the presence of some metal ions and organic compounds. The proposed method was successfully applied for determination of daphnetin in traditional Chinese medicine (Zushima) and Zushima tablets with satisfactory results. [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 highly sensitive voltammetric sensor, based on reduced graphene oxide on SWCNTs modified glassy carbon electrode (GCE), was constructed and used for sensitive detection of hesperetin. The electrochemical behavior of hesperetin at this sensor was investigated systematically and a novel voltammetric method for determination of hesperetin was proposed. The redox characters of hesperetin was discussed in detail and a reasonable reaction mechanism was proposed also. As the analytical method, the response currents were linear relationship with the hesperetin concentrations in the range of 5.0×10 −8 to 3.0×10 −6 mol L− 1 , with a detection limit of 2.0×10 −8 mol L −1 ( S / N =3). The method was also applied successfully to detect hesperetin in biological samples and Chinese herbal medicine Flos buddlejae with satisfactory results. [ABSTRACT FROM AUTHOR]

The electro-polymerization of l -Norvaline was investigated for the first time on glassy carbon electrode. The polymeric conditions and mechanism were discussed in detail. The electrochemical behaviors of metribuzin were studied systematically at this sensor and the dynamic parameters of electrode process were calculated. This electrochemical sensor, fabricated simply and very easy surface update, showed good response for metribuzin with a wide linear range from 6.43 × 10 − 3 to 1.07 μg/mL and a low detection limit of 2.14 × 10 − 3 μg/mL (S/N = 3). The proposed method was successfully applied to determine metribuzin in soil sample with satisfactory results. This work promoted the potential applications of amino acid materials in electrochemical sensors. [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 novel electrochemical sensor was designed and constructed for high-sensitive detection of Taxifolin based on Co 3 S 4 @MoS 2 loaded on reduced graphene oxide (RGO-Co 3 S 4 @MoS 2) as modified materials. It's the first time for Co 3 S 4 @MoS 2 was exploited to constructed electrochemical sensor. Owing to the Co 3 S 4 @MoS 2 providing a huge surface area to enrich more Taxifolin and the excellent electric conductivity of RGO, Taxifolin was detected sensitively with a linear range from 5.0 × 10 −9 to 1.0 × 10−6 mol L−1 and limit of detection down to 1.67 × 10−9 mol L−1 (S/N = 3). In addition, the sensor also demonstrated strong anti-interference properties in the presence of some metal ions and organic compounds. The proposed method was successfully applied for determination of Taxifolin in traditional Chinese medicine in fructus polygoni orientalis with satisfactory results. • RGO-Co 3 S 4 @MoS 2 was fabricated and used to constructed electrochemical sensor. • The RGO-Co 3 S 4 @MoS 2 /GCE exhibits extraordinary electrical properties toward Taxifolin. • The proposed electrochemical sensor shown a satisfactory analytical performance toward Taxifolin. [ABSTRACT FROM AUTHOR]