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Cai Z.,Xiamen University | Rong M.,Xiamen University | Zhao T.,Xiamen Huaxia College | Zhao L.,Xiamen Huaxia College | And 2 more authors.
Journal of Electroanalytical Chemistry | Year: 2015

A novel photoelectrochemical (PEC) sensing platform is fabricated using the composition of graphitic carbon nitride (g-C3N4), TiO2 nanoparticles (TiO2 NPs) and graphene (G) on an indium tin oxide (ITO) electrode. The graphene layer is acting as the supporter for g-C3N4 to form tightly G-C3N4 thin nanosheets, and behaves as an electron transfer medium to enhance the electron transport ability. Then, TiO2 NPs tightly anchor onto the G-C3N4 nanosheets to form G-C3N4/TiO2 nanocomposite. The photocurrent of G-C3N4/TiO2 drastically enhances compared to G-C3N4 and G-TiO2, which is attributed to the life improvement of the electron-hole pairs and the synergistic amplification between TiO2 NPs and C3N4. Interestingly, the photocurrent of G-C3N4/TiO2 nanocomposite is notably improved upon the addition of dopamine (DA). Based on the enhanced photocurrent signal, a PEC methodology for ultrasensitive determination of DA has been developed, which showed linearly enhanced photocurrent by increasing the DA concentration from 0.1 to 50 μM with a detection limit of 0.02 μM (S/N = 3) under optimized conditions. Therefore, the fabricated photoelectrochemical sensor provides a promising method in the sensing of biomolecules and extended the applications of C3N4-based nanocomposite in the field of PEC sensing. © 2015 Elsevier B.V. All rights reserved.


Zhou T.,China Academy of Safety Science and Technology | Yao Q.,Xiamen Huaxia College | Zhao T.,Xiamen Huaxia College | Chen X.,Xiamen University
Talanta | Year: 2015

Abstract A facile one-pot approach has been developed to prepare orange-emitting Cu nanoclusters (NCs) using tetrakis(hydroxymethyl)phosphonium chloride as a reducing agent and lipoic acid as a capping agent under an alkaline medium at room temperature. The as-prepared Cu NCs exhibited excellent water solubility, large Stokes shift, long lifetime and good dispersion. After the addition of polyvinyl pyrrolidone, the fluorescence intensity of dihydrolipoic acid-stabilized Cu NCs (DHLA-Cu NCs) was greatly enhanced, and their fluorescence signal remained stable for 5 weeks storage in the dark at room temperature. Based on H2O2-induced fluorescence quenching, DHLA-Cu NCs showed high sensitivity and selectivity for the detection of H2O2 in aqueous solution with a detection limit of 0.3 μM, and were applied successfully to the detection of H2O2 in human urine samples. © 2015 Elsevier B.V. All rights reserved.


Lin L.,Xiamen University | Song X.,Xiamen University | Chen Y.,Xiamen University | Rong M.,Xiamen University | And 4 more authors.
Analytica Chimica Acta | Year: 2015

In this paper, the highly intrinsic peroxidase-like catalytic activity of nitrogen-doped graphene quantum dots (N-GQDs) is revealed. This activity was greatly dependent on pH, temperature and H2O2 concentration. The experimental results showed that the stable N-GQDs could be used for the detection of H2O2 and glucose over a wide range of pH and temperature, offering a simple, highly selective and sensitive approach for their colorimetric sensing. The linearity between the analyte concentration and absorption ranged from 20 to 1170μM for H2O2 and 25 to 375μM for glucose with a detection limit of 5.3μM for H2O2 and 16μM for glucose. This assay was also successfully applied to the detection of glucose concentrations in diluted serum and fruit juice samples. © 2015 Elsevier B.V.


Zhao T.,Xiamen Huaxia College | Zhou T.,The Academy of Management | Yao Q.,Xiamen Huaxia College | Hao C.,Xiamen Huaxia College | Chen X.,Xiamen University
Journal of Environmental Science and Health - Part C Environmental Carcinogenesis and Ecotoxicology Reviews | Year: 2015

Metal nanoclusters (NCs), with dimensions between metal atoms and nanoparticles, have attracted more and more attention due to their unique physical and chemical properties. With their size approaching the Fermi wavelength of electrons, metal NCs possess molecule-like properties and excellent fluorescence emission. Owing to their ultrasmall size, strong fluorescence, and excellent biocompatibility, they have been widely studied in environmental and biological fields concerning their applications. In this review, we will introduce the properties of metal NCs, mainly focusing on the synthesis of metal alloy NCs and the recent progress in their applications in environmental monitoring and cancer therapy. Copyright © 2015 Taylor & Francis Group, LLC.


Zhao L.,Xiamen Huaxia College | Wu G.,Xiamen University | Cai Z.,Xiamen University | Zhao T.,Xiamen Huaxia College | And 2 more authors.
Microchimica Acta | Year: 2015

We describe an anodic stripping voltammetric (ASV) method for glucose sensing that widely expands the typical amperometric i-t response of glucose sensors. The electrode is based on a working electrode consisting of a glassy carbon electrode modified with Pt-Pd nanoparticles (NPs; in an atomic ratio of 3:1) on a reduced graphene oxide (rGO) support. The material was prepared via the spontaneous redox reaction between rGO, PdCl42− and PtCl42− without any additional reductant or surfactant. Unlike known Pt-based sensors, the use of Pt3Pd NPs results in an ultrasensitive ASV approach for sensing glucose even at near-neutral pH values. If operated at a working voltage as low as 0.06 V (vs. SCE), the modified electrode can detect glucose in the 2 nM to 300 μM concentration range. The lowest detectable concentration is 2 nM which is much lower than the LODs obtained with other amperometric i-t type sensing approaches, most of which have LODs at a μM level. The sensor is not interfered by the presence of 0.1 M of NaCl. © 2015, Springer-Verlag Wien.


Cai Z.,Xiamen University | Zhao L.,Xiamen Huaxia College | Zhao T.,Xiamen Huaxia College | Wang Y.,Xiamen University | Chen X.,Xiamen University
Analytical Sciences | Year: 2015

A novel non-enzymatic oxalic acid (OA) sensor was developed using a nanocrystal PtPd loaded reduced graphene nanosheets (PtPdNCs/RGO)-modified electrode. PtPdNCs/RGO were successfully achieved by a facile, one-step and template-free method, in which PtPd nanoparticles with 100 nm-scale were assembled from polyhedral PtPd nanocrystals of various shapes and dispersed on the graphene nanosheets. Resulting PtPdNCs/RGO were characterized and used for PtPdNCs/RGO-modified electrodes. Electrochemical oxidation of OA on the modified electrode was investigated by cyclic voltammetry and differential pulse voltammetry (DPV). Well-defined peaks of OA oxidation could be obtained using an electrode that indicated its high electrochemical activity. The concentration of OA and the current responses could be obtained in the ranges of 0.5 - 10 and 10 - 35 mM with correlation coefficients of 0.9994 and 0.9952; the detection limit (S/N = 3) was found to be 0.05 mM. The modified electrode presented good characteristics in terms of both stability and reproducibility, promising its applicability in practical analysis. © 2015 The Japan Society for Analytical Chemistry.


PubMed | Xiamen University, Xiamen Huaxia College and Fujian Agriculture and forestry University
Type: | Journal: Analytica chimica acta | Year: 2015

In this work, europium-decorated graphene quantum dots (Eu-GQDs) were prepared by treating three-dimensional Eu-decorated graphene (3D Eu-graphene) via a strong acid treatment. Various characterizations revealed that Eu atoms were successfully complexed with the oxygen functional groups on the surface of graphene quantum dots (GQDs) with the atomic ratio of 2.54%. Compared with Eu free GQDs, the introduction of Eu atoms enhanced the electron density and improved the surface chemical activities of Eu-GQDs. Therefore, the obtained Eu-GQDs were used as a novel off-on fluorescent probe for the label-free determination of Cu(2+) and l-cysteine (L-Cys) with high sensitivity and selectivity. The fluorescence intensity of Eu-GQDs was quenched in the presence of Cu(2+) owing to the coordination reaction between Cu(2+) and carboxyl groups on the surface of the Eu-GQDs. The fluorescence intensity of Eu-GQDs recovered with the subsequent addition of L-Cys because of the strong affinity of Cu(2+) to L-Cys via the Cu-S bond. The experimental results showed that the fluorescence variation of the proposed approach had a good linear relationship in the range of 0.1-10M for Cu(2+) and 0.5-50M for L-Cys with corresponding detection limits of 0.056M for Cu(2+) and 0.31M for L-Cys. The current approach also displayed a special response to Cu(2+) and L-Cys over the other co-existing metal ions and amino acids, and the results obtained from buffer-diluted serum samples suggested its applicability in biological samples.


PubMed | Xiamen Huaxia College and Xiamen University
Type: | Journal: Analytica chimica acta | Year: 2015

In this paper, the highly intrinsic peroxidase-like catalytic activity of nitrogen-doped graphene quantum dots (N-GQDs) is revealed. This activity was greatly dependent on pH, temperature and H2O2 concentration. The experimental results showed that the stable N-GQDs could be used for the detection of H2O2 and glucose over a wide range of pH and temperature, offering a simple, highly selective and sensitive approach for their colorimetric sensing. The linearity between the analyte concentration and absorption ranged from 20 to 1170 M for H2O2 and 25 to 375 M for glucose with a detection limit of 5.3 M for H2O2 and 16 M for glucose. This assay was also successfully applied to the detection of glucose concentrations in diluted serum and fruit juice samples.


Yin J.-Y.,Nanchang University | Chen H.-H.,Nanchang University | Lin H.-X.,Xiamen Huaxia College | Xie M.-Y.,Nanchang University | Nie S.-P.,Nanchang University
Molecules | Year: 2016

Polysaccharide from the seeds of Plantago asiatica L. has many bioactivities, but few papers report on the structural and rheological characteristics of the alkaline extract. The alkaline extracted polysaccharide was prepared from seeds of P. asiatica L. and named herein as alkaline extracted polysaccharide from seeds of P. asiatica L. (PLAP). Its structural and rheological properties were characterized by monosaccharide composition, methylation, GC-MS and rheometry. PLAP, as an acidic arabinoxylan, was mainly composed of 1,2,4-linked Xylp and 1,3,4-linked Xylp residues. PLAP solution showed pseudoplastic behavior, and weak gelling properties at high concentration. Sodium and especially calcium ions played a significant role in increasing the apparent viscosity and gel strength. © 2016 by the authors; licensee MDPI, Basel, Switzerland.


PubMed | Nanchang University and Xiamen Huaxia College
Type: Journal Article | Journal: Molecules (Basel, Switzerland) | Year: 2016

Polysaccharide from the seeds of Plantago asiatica L. has many bioactivities, but few papers report on the structural and rheological characteristics of the alkaline extract. The alkaline extracted polysaccharide was prepared from seeds of P. asiatica L. and named herein as alkaline extracted polysaccharide from seeds of P. asiatica L. (PLAP). Its structural and rheological properties were characterized by monosaccharide composition, methylation, GC-MS and rheometry. PLAP, as an acidic arabinoxylan, was mainly composed of 1,2,4-linked Xylp and 1,3,4-linked Xylp residues. PLAP solution showed pseudoplastic behavior, and weak gelling properties at high concentration. Sodium and especially calcium ions played a significant role in increasing the apparent viscosity and gel strength.

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