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This paper presents a microsensor chip integrated with a gold nanoparticles-modified ultramicroelectrode array (UMEA) as the working electrode for the detection of copper ions in water. The microsensor chip was fabricated with Micro-Electromechanical System technique. Gold nanoparticles were electrodeposited onto the surface of UMEA at a constant potential of −0.3 V. The ratio d/ Rb of interelectrode spacing ( d) over the individual electrode's radius ( Rb) was investigated to improve the electrochemical performance. The UMEA with a d/ Rb of 20 showed the best hemispherical diffusion mode, resulted in fast response time and high current response. The gold nanoparticles increased the active surface area of UMEA by not changing the geometries of UMEA, and the current response was increased further. Incorporating the optimized characteristic of UMEA and gold nanoparticles, the microsensor showed a good linear range from 0.5 to 200 µg L−1 of copper ions in the acetate buffer solutions with the method of square wave stripping voltammetry. Compared with the gold nanoparticles-modified disk electrode, the gold nanoparticles-modified UMEA showed higher sensitivity (0.024 µA mm−2 µg−1 L) and lower limit of detection (0.2 µg L−1). Water samples from river water and tap water were analyzed by the microsensor chip with recovery ranging from 100.7 % to 107.8 %. [ABSTRACT FROM AUTHOR]

In this work, three heavy metals (Cu(II), Pb(II) and Zn(II)) in wide potential window were simultaneously detected on tin film/gold nanoparticles/gold microelectrode (Sn/GNPs/gold microelectrode) by the method of square wave stripping voltammetry. The Sn/GNPs/gold microelectrode was fabricated by in situ plating of a Sn film on a gold nanoparticles (GNPs) modified gold microelectrode. The influence of hydrogen overflow on stripping of Zn(II) on the gold microelectrode was reduced by modification of GNPs, which made the stripping potential of target metals shift positively. The interference of sulfhydryl groups was reduced and the selectivity of the microelectrode was improved due to the addition of Sn in the detection solution. After accumulation at −1.4 V for 300 s in acetate buffer solution (0.1 mol L−1, pH 4.5), the Sn/GNPs/gold microelectrode revealed a good linear behavior in the examined concentration ranges from 5 to 500 µg L−1 for Cu(II) and Pb(II), and from 10 to 500 µg L−1 for Zn(II), with a limit of detection of 2 µg L−1 for Cu(II), 3 µg L−1 for Pb(II) and 5 µg L−1 for Zn(II) ( S/ N=3). When compared with a Sb/GNPs/gold microelectrode and a Bi/GNPs/gold microelectrode, the Sn/GNPs/gold microelectrode showed the best stripping performance to Cu(II), Pb(II) and Zn(II). As a new type of environment-friendly electrode, the Sn/GNPs/gold microelectrode has potential applications for detection of heavy metals. [ABSTRACT FROM AUTHOR]

A 3D dendritic nanostructure of silver-array (DSA) was prepared via electrodeposition on an interdigitated array (IDA) microelectrode. For preparation of this nanostructure, the optimal parameters such as deposition potential, deposition time, the electrode bandwidth and gap size were systematically investigated. It was found that the edge effect of the IDA microelectrode is a key factor for controlling the 3D dendritic growth of silver. Furthermore, the formation of the 3D dendritic morphology was discussed from the aspect of electrochemical nucleation theory and nonequilibrium growth dynamics to give a deep understanding of its growth mechanism. For its potential practical application, we showed that the as-prepared 3D DSA nanomaterial exhibited high electrocatalytic reduction ability to nitrate in neutral solution and excellent performance for nitrate determination. An amperometric nitrate microsensor based on the 3D DSA was obtained. [ABSTRACT FROM AUTHOR]

This work mainly describes an electrochemical microsensor based on the reduction of molybdophosphate complex for total phosphorus (TP) determinations in water. The microelectrode was fabricated using microelectromechanical systems (MEMS) techniques and porous, branching gold nanoparticles (AuNPs) were electrodeposited on the microelectrode to improve its sensitivity. Calibration of the microsensor was performed with standard phosphate solutions prepared with KH2 PO4 with pH adjusted to 1.0. The experimental results showed that both sensitivity and current response are improved effectively using this modified microelectrodes: The limit of detection of the microsensor is 1.2 × 10−7 mol/l and linear range is 3 × 10−7 to 3 × 10−4 mol/l. The sensitivity of unmodified electrode is −0.27 nA/μmol·l−1 (R2 = 0.994), whereas the sensitivity of AuNPs modified electrode is −0.89 nA/μmol l−1 (R2 = 0.98). The current response of modified electrode is 6 times larger than that of unmodified electrode in average. Detection of TP was also carried out with digested TP standard solutions for both modified and unmodified electrodes, and results were consistent with the nominal value of phosphorus concentration. This microsensor provides the probability of combining TP detection device with micro‐digesting device to form a TP detection system, which can realise the automotive and on‐line monitoring of TP in surface water. [ABSTRACT FROM AUTHOR]

Sacred lotus ( Nelumbo nucifera) is an ornamental plant that is also used for food and medicine. This basal eudicot species is especially important from an evolutionary perspective, as it occupies a critical phylogenetic position in flowering plants. Here we report the draft genome of a wild strain of sacred lotus. The assembled genome is 792 Mb, which is approximately 85-90% of genome size estimates. We annotated 392 Mb of repeat sequences and 36 385 protein-coding genes within the genome. Using these sequence data, we constructed a phylogenetic tree and confirmed the basal location of sacred lotus within eudicots. Importantly, we found evidence for a relatively recent whole-genome duplication event; any indication of the ancient paleo-hexaploid event was, however, absent. Genomic analysis revealed evidence of positive selection within 28 embryo-defective genes and one annexin gene that may be related to the long-term viability of sacred lotus seed. We also identified a significant expansion of starch synthase genes, which probably elevated starch levels within the rhizome of sacred lotus. Sequencing this strain of sacred lotus thus provided important insights into the evolution of flowering plant and revealed genetic mechanisms that influence seed dormancy and starch synthesis. [ABSTRACT FROM AUTHOR]

Abstract: Several studies suggest that the open reading frame 3 (ORF3) gene of porcine epidemic diarrhea virus (PEDV) is related to viral infectivity and pathogenicity, but its function remains unknown. Here, we propose a structure model of the ORF3 protein consisting of four TM domains and forming a tetrameric assembly. ORF3 protein can be detected in PEDV-infected cells and it functions as an ion channel in both Xenopus laevis oocytes and yeast. Mutation analysis showed that Tyr170 in TM4 is important for potassium channel activity. Furthermore, viral production is reduced in infected Vero cells when ORF3 gene is silenced by siRNA. Interestingly, the ORF3 gene from an attenuated PEDV encodes a truncated protein with 49 nucleotide deletions, which lacks the ion channel activity. [Copyright &y& Elsevier]

Abstract: The spike (S) protein of severe acute respiratory syndrome coronavirus (SARS-CoV) is an important viral structural protein. Based on bioinformatics analysis, 10 antigenic peptides derived from the S protein sequence were selected and synthesized. The antigenicity and immunoreactivity of all the peptides were tested in vivo and in vitro. Four peptides (P6, P8, P9 and P10) which contain B cell epitopes of the S protein were identified, and P8 peptide was confirmed in vivo to have a potential in serological diagnosis. By using a syncytia formation model, we tested the neutralization ability of all 10 peptides and their corresponding antibodies. It is interesting to find that P8 and P9 peptides inhibited syncytia formation, suggesting that the P8 and P9 spanning regions may provide a good target for anti-SARS-CoV drug design. Our data suggest that we have identified peptides derived from the S protein of SARS-CoV, which are useful for SARS treatment and diagnosis. [Copyright &y& Elsevier]