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Lin M.,CAS Yantai Institute of Coastal Zone Research | Lin M.,Shandong Provincial Key Laboratory of Coastal Zone Environmental Processes | Hu X.,CAS Yantai Institute of Coastal Zone Research | Hu X.,Shandong Provincial Key Laboratory of Coastal Zone Environmental Processes | And 2 more authors.
Analytica Chimica Acta | Year: 2012

A novel electrochemical biosensor based on functionalized polypyrrole (PPy) nanotube arrays modified with a tripeptide (Gly-Gly-His) proved to be highly effective for electrochemical analysis of copper ions (Cu2+). The vertically oriented PPy nanotube arrays were electropolymerized by using modified zinc oxide (ZnO) nanowire arrays as templates which were electrodeposited on indium-tin oxide (ITO) coated glass substrates. The electrodes were functionalized by appending pyrrole-α-carboxylic acid onto the surface of polypyrrole nanotube arrays by electrochemical polymerization. The carboxylic groups of the polymer were covalently coupled with the amine groups of the tripeptide, and its structural features were confirmed by attenuated total reflection infrared (ATR-IR) spectroscopy. The tripeptide modified PPy nanotube arrays electrode was used for the electrochemical analysis of various trace copper ions by square wave voltammetry. The electrode was found to be highly sensitive and selective to Cu2+ in the range of 0.1-30μM. Furthermore, the developed biosensor exhibited a high stability and reproducibility, despite the repeated use of the biosensor electrode. © 2012 Elsevier B.V.

Zhang G.,National University of Singapore | Zhang G.,CAS Yantai Institute of Coastal Zone Research | Zhang G.,Shandong Provincial Key Laboratory of Coastal Zone Environmental Processes | Khorshed A.,National University of Singapore | Paul Chen J.,National University of Singapore
Journal of Colloid and Interface Science | Year: 2013

Arsenate and arsenite typically co-exist in groundwater. Arsenite is more toxic than arsenate, while it is more difficult to be removed than arsenate. In order to effectively remove arsenate and arsenite simultaneously from water solution, a nanostructured zirconium-manganese binary hydrous oxide was successfully developed in this study. The amorphous sorbent was aggregate of nanoparticles with a high surface area of 213m2g-1. Our sorption experiments showed that the nano-scale particles could effectively oxidize As(III) to As(V) and greatly remove both As(V) and As(III). The maximal adsorption capacities of As(V) and As(III) were 80 and 104mgg-1 at pH 5.0, respectively. As(V) uptake may be mainly achieved through replacement of hydroxyl groups and sulfate anions on the surface of the oxide and formation of inner complexes. The As(III) removal was essentially due to a sorption coupled with oxidation process; the MnO2 was mainly responsible for oxidization of As(III) to As(V) that was subsequently adsorbed onto ZrO2. © 2012 Elsevier Inc.

Li G.,CAS Yantai Institute of Coastal Zone Research | Li G.,Shandong Provincial Key Laboratory of Coastal Zone Environmental Processes | Gao S.,Yantai University | Zhang G.,CAS Yantai Institute of Coastal Zone Research | And 2 more authors.
Chemical Engineering Journal | Year: 2014

Phosphate is one of the main elements causing eutrophication and hence the development of high-efficiency and low-cost technologies for phosphate removal from water is of vital importance to alleviate the situation. In this study, nanostructured Fe-Cu binary oxides were synthesized via a facile coprecipitation process and its performance on phosphate removal was systematically evaluated. The as-prepared adsorbent with a Cu/Fe molar ratio of 1:2 was proved to possess the highest phosphate adsorption capacity. The adsorption isotherm data gave better fit to the Langmuir model, with a maximum phosphate adsorption capacity of 35.2mgg-1 at pH 7.0±0.1. Kinetic data correlated well with the pseudo-second-order kinetic model, indicating that the adsorption process might be chemical sorption. Thermodynamic data validated that the phosphate adsorption was an endothermic process. The solution pH has a big impact on the phosphate adsorption on the sorbent and acidic condition was favorable for the adsorption. The coexisting Cl-, SO42- and HCO3- anions had no significant influence on phosphate adsorption, while the present F- and SiO32- could suppress its adsorption, especially at high concentration level. The phosphate adsorption might be mainly achieved by the replacement of surface sulfate and hydroxyl groups by the phosphate species and formation of inner-sphere surface complexes at the water/oxide interface. Moreover, the spent Fe-Cu binary oxide could be effectively regenerated by NaOH solution for reuse. The high phosphate uptake capability and good reusability of the Fe-Cu binary oxide make it a potentially attractive adsorbent for the removal of phosphate from water. © 2013 Elsevier B.V.

Hong H.-S.,Xiamen University | Wang Y.-J.,Chinese Academy of Sciences | Wang Y.-J.,Shandong Provincial Key Laboratory of Coastal Zone Environmental Processes | Wang Y.-J.,CAS Yantai Institute of Coastal Zone Research | Wang D.-Z.,Xiamen University
Continental Shelf Research | Year: 2011

This study investigated the activities of two nitrogen assimilation enzymes, nitrate reductase (NR) and glutamine synthetase (GS) in phytoplankton in relation to sample, as well as the nutrient levels and phytoplankton biomass (Chl- a concentrations) during an upwelling event in the southern Taiwan Strait during an upwelling period from 6 to 12 July, 2005. The results showed that high NR activity (NRA) was always found with low nitrate and high Chl-a concentrations, while GS activity (GSA) exhibited positive correlations with ammonium and Chl-a concentration. Both NRA and GSA varied with the time and stage of upwelling: high NRA and GSA were observed initially at the subsurface layers in the early stage of upwelling, accompanied by the consumption of nutrients and the increase of Chl-a concentration; and then at the surface with high Chl-a concentrations in the middle and late stages of upwelling. Results from in situ enzyme bioassays on water samples along the tracing of upwelling track and on board mesocosm experiments on board the ship showed that there was a time-lag between nitrate addition and NRA and GSA, but. However, no time-lag was found between ammonium addition and GSA. The present results indicated that both NRA and GSA reflect the status of ambient nitrogen levels and the assimilation process of the phytoplankton, and could be used as effective parameters for the analysis of the physiological response of the phytoplankton to nitrogen variations during upwelling periods. Measurements of NRA and GSA in the phytoplankton in newly upwelled water appeared to provide ecophysiological indicators of phytoplankton, which will make it possible to trace during the sequence of upwelling events (such as nutrient supplementation) leading to enhanced productivity. © 2011 Elsevier Ltd.

Wang X.,Qufu Normal University | Wang X.,CAS Yantai Institute of Coastal Zone Research | Wang X.,Shandong Provincial Key Laboratory of Coastal Zone Environmental Processes | Chen L.,CAS Yantai Institute of Coastal Zone Research | And 3 more authors.
Microchimica Acta | Year: 2014

We have developed a method for the colorimetric determination of copper ions (Cu2+) that is based on the use of silver-coated gold nanorods (Au@Ag NRs). Its outstanding selectivity and sensitivity result from the catalytic leaching process that occurs between Cu2+, thiosulfate (S2O3 2-), and the surface of the Au@Ag NRs. The intrinsic color of the Au@Ag NRs changes from bright red to bluish green with decreasing thickness of the silver coating. The addition of Cu2+ accelerates the leaching of silver from the shell caused in the presence of S2O3 2-. This result in a decrease in the thickness of the silver shell which is accompanied a change in color and absorption spectra of the colloidal solution. The shifts in the absorption maxima are linearly related to the concentrations of Cu2+ over the 3-1,000 nM concentration range (R = 0.996). The method is cost effective and was applied to the determination of Cu2+ in real water samples. [Figure not available: see fulltext.] © 2013 Springer-Verlag Wien.

Ding J.,CAS Yantai Institute of Coastal Zone Research | Ding J.,Shandong Provincial Key Laboratory of Coastal Zone Environmental Processes | Ding J.,University of Chinese Academy of Sciences | Qin W.,CAS Yantai Institute of Coastal Zone Research | And 5 more authors.
Biosensors and Bioelectronics | Year: 2013

In this article, we introduce a general, sensitive, facile, and label-free potentiometric assay based on metal-mediated DNA base pairs. A nucleic acid with one adenosine-5'-triphosphate (ATP) binding sequence (aptamer) in the middle and two cytosine(C)-rich sequences at the lateral portions was employed as a model. A rigid hairpin structure can be formed in the presence of Ag+ ions, in which the C residues of the spatially separated nucleotides are linked by the ions. The strong interaction between Ag+ ions and cytosines forms a stable C-Ag+-C structure, which could reduce the concentration of silver ions released from the polymeric membrane silver ion-selective electrode (ISE) at the sample-membrane interface and decrease the potential response. In the presence of its target, the aptamer (the loop sequence of the probe) binds specifically to the target via reaction incubation. Such target-binding induced aptamer conformational change prevents the formation of C-Ag+-C structure, leaving more silver ions at the sample-membrane interface, which can be detected by the silver ISE. ATP can be quantified in the range of 0.5-3.0μM with a detection limit of 0.37μM. The relative standard deviation for 5μM ATP is 5.5%. For the proposed method, the combination of using ion fluxes of silver ions as modulating reagents and as signal reporters greatly simplifies the detection procedures. In addition, by changing the binding sequence in the middle of the probe, the present detection method will be able to explore new applications of ISE for the detection of a large variety of targets. © 2013 Elsevier B.V.

Ding J.,CAS Yantai Institute of Coastal Zone Research | Ding J.,Shandong Provincial Key Laboratory of Coastal Zone Environmental Processes | Ding J.,University of Chinese Academy of Sciences | Qin W.,CAS Yantai Institute of Coastal Zone Research | Qin W.,Shandong Provincial Key Laboratory of Coastal Zone Environmental Processes
Biosensors and Bioelectronics | Year: 2013

A simple, general and label-free potentiometric method to measure nuclease activities and oxidative DNA damage in a homogeneous solution using a polycation-sensitive membrane electrode is reported. Protamine, a linear polyionic species, is used as an indicator to report the cleavage of DNA by nucleases such as restriction and nonspecific nucleases, and the damage of DNA induced by hydroxyl radicals. Measurements can be done with a titration mode or a direct detection mode. For the potentiometric titration mode, the enzymatic cleavage dramatically affects the electrostatical interaction between DNA and protamine and thus shifts the response curve for the potentiometric titration of the DNA with protamine. Under the optimized conditions, the enzyme activities can be sensed potentiometrically with detection limits of 2.7×10-4U/L for S1 nuclease, and of 3.9×10-4U/L for DNase I. For the direct detection mode, a biocomplex between protamine and DNA is used as a substrate. The nuclease of interest cleaves the DNA from the protamine/DNA complex into smaller fragments, so that free protamine is generated and can be detected potentiometrically via the polycation-sensitive membrane electrode. Using a direct measurement, the nuclease activities could be rapidly detected with detection limits of 3.2×10-4U/L for S1 nuclease, and of 4.5×10-4U/L for DNase I. Moreover, the proposed potentiometric assays demonstrate the potential applications in the detection of hydroxyl radicals. It is anticipated that the present potentiometric strategy will provide a promising platform for high-throughput screening of nucleases, reactive oxygen species and the drugs with potential inhibition abilities. © 2013 Elsevier B.V.

Ma J.,Qingdao Technological University | Lu W.,Qingdao Technological University | Lu W.,Chinese Academy of Sciences | Lu W.,Shandong Provincial Key Laboratory of Coastal Zone Environmental Processes | And 4 more authors.
Current Analytical Chemistry | Year: 2012

Dispersive liquid-liquid microextraction (DLLME) is a novel microextraction technique with a great potential in sample pretreatment, which has been increasingly used for preconcentration of diverse analytes. This review updates the state of the art and discusses promising prospects of DLLME, especially focuses on its combined use with chromatographic techniques for organic compounds analysis in environmental water samples. General and specific concepts of the fundamental theory of DLLME are described, and examples of recent innovations and applications are provided to demonstrate its potential for the determination of a wide range of organic compounds in various water matrices. Moreover, some limitations related to DLLME are also discussed in detail, and an outlook on the future of the technique, specifically its coupling with other pretreatment approaches, separation and detection techniques, is also given. © 2012 Bentham Science Publishers.

Zhang G.,CAS Yantai Institute of Coastal Zone Research | Zhang G.,Shandong Provincial Key Laboratory of Coastal Zone Environmental Processes | Ren Z.,CAS Yantai Institute of Coastal Zone Research | Ren Z.,Shandong Provincial Key Laboratory of Coastal Zone Environmental Processes | And 3 more authors.
Water Research | Year: 2013

To obtain a highly efficient and low-cost adsorbent for arsenic removal from water, a novel nanostructured Fe-Cu binary oxide was synthesized via a facile co-precipitation method. Various techniques including BET surface area measurement, powder XRD, SEM, and XPS were used to characterize the synthetic Fe-Cu binary oxide. It showed that the oxide was poorly crystalline, 2-line ferrihydrite-like and was aggregated with many nanosized particles. Laboratory experiments were performed to investigate adsorption kinetics, adsorption isotherms, pH adsorption edge and regeneration of spent adsorbent. The results indicated that the Fe-Cu binary oxide with a Cu: Fe molar ratio of 1:2 had excellent performance in removing both As(V) and As(III) from water, and the maximal adsorption capacities for As(V) and As(III) were 82.7 and 122.3mg/g at pH 7.0, respectively. The values are favorable, compared to those reported in the literature using other adsorbents. The coexisting sulfate and carbonate had no significant effect on arsenic removal. However, the presence of phosphate obviously inhibited the arsenic removal, especially at high concentrations. Moreover, the Fe-Cu binary oxide could be readily regenerated using NaOH solution and be repeatedly used. The Fe-Cu binary oxide could be a promising adsorbent for both As(V) and As(III) removal because of its excellent performance, facile and low-cost synthesis process, and easy regeneration. © 2013 Elsevier Ltd.

Wang Y.,CAS Yantai Institute of Coastal Zone Research | Wang Y.,Chinese Academy of Sciences | Chen L.,Shandong Provincial Key Laboratory of Coastal Zone Environmental Processes
Nanomedicine: Nanotechnology, Biology, and Medicine | Year: 2011

Quantum dots (QDs) have proven themselves as powerful inorganic fluorescent probes, especially for long term, multiplexed imaging and detection. The newly developed QDs labeling techniques have facilitated the study of drug delivery on the level of living cells and small animals. Moreover, based on QDs and fluorescence imaging system, multifunctional nanocomplex integrated targeting, imaging and therapeutic functionalities have become effective materials for synchronous cancer diagnosis and treatment. In this review, we will summarize the recent advances of QDs in the research of drug delivery system from the following aspects: surface modification strategies of QDs for drug delivery, QDs as drug nanocarriers, QD-labeled drug nanocarriers, QD-based fluorescence resonance energy transfer (FRET) technique for drug release study as well as the development of multifunctional nanomedicines. Possible perspective in this field will also be discussed. © 2010 Elsevier Inc.

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