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Wang X.,Analysis in Universities of Shandong | Chu C.,Analysis in Universities of Shandong | Shen L.,Analysis in Universities of Shandong | Deng W.,Analysis in Universities of Shandong | And 4 more authors.
Sensors and Actuators, B: Chemical

We reported here the synthesis of thin MoS2 nanosheets, which showed a good catalysis of H2O2. The MoS2 nanosheets were further synthetized into nano-composite MoS2-Au, and the MoS2-Au was found with a better catalysis property of H2O2 and well electroconductibility. Furthermore, we composed Ag nanospheres (AgNPs), which have good electricity and large surface area. The prepared AgNPs and MoS2-Au were applied in a sandwich-type immunosensor for detecting carcinoembryonic antigen (CEA). In the immunosensor, MoS2-Au acted as the solid support for CEA primary antibody and AgNPs were employed as the supporter of glucose oxidase (GOx) and CEA secondary antibody. With the addition of glucose, the hydrogen peroxide was prepared and the MoS2-Au catalyzed hydrogen peroxide that the current peak was presented with the differential pulse voltammetry (DPV). The proposed immunosensor enabled CEA concentrations to be determined in the range of 1 pg mL-1 to 50 ng mL-1, with a detection limit of 0.27 pg mL-1. The immunosensor showed low detection limit, good specificity, high sensitivity and reproducibility. Satisfactory results were obtained for determination of CEA in human serum albumin samples. This work is to open new avenues in the application of AuNPs dotted MoS2 composite interface for sensitive electrochemical immunoassay. Hence, the proposed electrochemical immunosensor could become a promising method for tumor marker detection. © 2014 Elsevier B.V. All rights reserved. Source

Wu D.,Analysis in Universities of Shandong | Li Y.,Analysis in Universities of Shandong | Zhang Y.,Analysis in Universities of Shandong | Wang P.,Analysis in Universities of Shandong | And 2 more authors.
Electrochimica Acta

The electrochemical sensor based on amino-group functionalized mesoporous Fe3O4 (Fe3O4-NH2) @graphene sheets (GS) was constructed to simultaneously determine small biomolecules such as ascorbic acid (AA), dopamine (DA) and uric acid (UA). Due to the synergetic effect between GS and Fe3O4-NH 2, the modified glassy carbon electrode not only improved the electrochemical catalytic oxidation of AA, DA, and UA, but also resolved the overlapping anodic peaks. Several important parameters controlling the performance of the electrochemical sensor were investigated and optimized. Using the modified electrode with differential pulse voltammetry (DPV) method, the linear response ranges for the determination of AA, DA, and UA were 5.0-1600 μmol L-1, 0.2-38 μmol L-1, and 1.0-850 μmol L-1 in the co-existence systems of these three species under optimum condition, respectively. The detection limits (S/N = 3) were found to be 0.074 μmol L-1, 0.126 μmol L-1, and 0.056 μmol L -1 for the determination of AA, DA, and UA, respectively. Satisfactory results were achieved for the determination of DA, AA, and UA in DA hydrochloride injection, vitamin C injection, and human urine samples, respectively. The results imply that the electrochemical sensor has the advantages of simplicity, high sensitivity and good selectivity.© 2013 Elsevier Ltd. All rights reserved. Source

Ma H.,Analysis in Universities of Shandong | Zhang X.,Analysis in Universities of Shandong | Li X.,Analysis in Universities of Shandong | Li R.,Analysis in Universities of Shandong | And 2 more authors.

A highly sensitive electrochemical immunosensor for detection of typical bladder cancer biomarker-nuclear matrix protein 22 (NMP22) was developed by using reduced graphene oxide-tetraethylene pentamine (rGO-TEPA) and trimetallic AuPdPt nanoparticles (NPs). rGO-TEPA was used as the ideal material for signal amplification and AuPdPt NPs immobilization due to its excellent conductivity and large surface area. An effective platform was constructed for antibodies anchoring by using AuPdPt NPs, which kept the antibodies' high stability and bioactivity. Moreover, AuPdPt NPs could accelerate the electron transfer and enhance the signal response, which assisted by the synergistic effect of the three different metals (Au, Pd and Pt). The proposed immunosensor showed satisfied performance such as simple fabrication, low detection limits (0.01 U/mL), wide linear range (from 0.040 to 20 U/mL), short analysis time (2 min), high stability and selectivity in the detection of NMP22. Furthermore, the proposed immunosensor was employed to test real urine samples with satisfactory results. © 2015 Elsevier B.V. All rights reserved. Source

Han T.,Analysis in Universities of Shandong | Yan T.,Analysis in Universities of Shandong | Li Y.,Analysis in Universities of Shandong | Cao W.,Analysis in Universities of Shandong | And 3 more authors.

An eco-friendly approach for the synthesis of nitrogen-doped carbon quantum dots (NCQDs) has been developed by the carbonization of diethylene triamine pentacetate acid (DTPA). In contrast to previous methods, neither strong acid treatment nor further surface modification is necessary for this synthetic process. The prepared NCQDs with average diameters of 2.5 nm exhibit excitation-independent photoluminescent behavior. Furthermore, the synthetic NCQDs have abundant carboxy groups and exhibit strong electrochemiluminescent (ECL) activity with K2S2O8 as coreactant on the glassy carbon electrode (GCE). Compared to pure CQDs, NCQDs exhibited stronger and more stable ECL signals due to easier electro-reduction of NCQDs generating more abundant NCQDs-. Importantly, these NCQDs are demonstrated to be excellent ECL luminophor for protein detection due to their stable emission, well dispersibility, low toxicity and good compatibility with biomolecules. Accordingly, the NCQDs were used to construct a novel ECL immunosensor for detection of human IgG (HIgG) which revealed good stability, reproducibility and selectivity. © 2015 Elsevier Ltd. All rights reserved. Source

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