A label-free electrochemical impedance aptasensor for cylindrospermopsin detection based on thionine-graphene nanocomposites

It is important to develop methods to determine cylindrospermopsin (CYN) at trace levels since CYN is a kind of widespread cyanobacterial toxin in water sources. In this study, a label-free impedimetric aptasensor has been fabricated for detecting CYN. In this case, the amino-substituted aptamer of CYN was co-valently grafted onto the surface of the thionine-graphene (TH-G) nanocomposite through the crosslinker glutaraldehyde (GA). The reaction of the aptamer with CYN was monitored by electrochemical impedance spectroscopy because the CYN induced conformation change of the aptamer can cause a remarkable decrease of the electron transfer resistance. Under optimum conditions, the aptasensor exhibits high sensitivity and a low detection limit for CYN determination. The CYN can be quantified in a wide range of 0.39 to 78 ng mL(-1) with a good linearity (R-2 = 0.9968) and a low detection limit of 0.117 ng mL(-1). In addition, the proposed aptasensor displays excellent stability, reusability and reproducibility

Self-assembly and chiroptical property of poly(N-acryloyl-L-amino acid) grafted celluloses synthesized by RAFT polymerization

Three amphiphilic poly(N-acryloyl-L-amino acid) grafted celluloses were prepared by RAFT polymerization of N-acryloyl-L-amino acid, where amino acid is alanine, proline or glutamic acid, onto cellulose backbones. The chemical structure and solution properties of the brush copolymers were characterized with FTIR, NMR and wide angle X-ray diffraction (WAXD). The thermal stability of the brush copolymers was estimated by thermal gravimetric analysis (TGA). Circular dichroism (CD) and specific rotation measurements confirmed that these grafted celluloses had characteristic chiroptical properties. The amphiphilic brush copolymers self-assembled into micelles in the aqueous solution as confirmed by transmission electron microscopy (TEM) and dynamic light scattering (DLS) analyses. The micellar aggregates showed a tunable pH-responsive property and disaggregated to form unimolecular micelles at higher pH in diluted solutions. The brush copolymers have potential applications in controlled drug release and high-performance liquid chromatography, and so forth. (C) 2014 Elsevier Ltd. All rights reserved

Ultrathin graphitic C3N4 nanofibers: Hydrolysis-driven top-down rapid synthesis and application as a novel fluorosensor for rapid, sensitive, and selective detection of Fe3+

Ultrathin graphitic C3N4(g-C3N4) nanofibers about 5-10 nm in diameters have been rapidly prepared via alkali-catalyzed hydrolysis of bulk g-C3N4 in concentrated alkaline aqueous solution. The morphologies of the g-C3N4 nanostructures can be facilely controlled by varying reaction time, and a scissoring mechanism is proposed to explain the formation process involved. The g-C3N4 nanofibers can serve as a novel fluorosensor for rapid Fe3+ detection with high sensitivity and selectivity. (C) 2015 Elsevier B.V. All rights reserved

A robust and low-cost strategy to prepare Cu2ZnSnS4 precursor solution and its application in Cu2ZnSn(S,Se)(4) solar cells

The metal chalcogenides are excellent choices as absorbers and buffer-layers in thin film solar cells. Versatile chemical approaches provide endless possibilities to prepare metal sulfide precursor solutions. Recently, Cu2ZnSnS(Se)(4) thin films have played an important role in fabricating low-cost and high-efficiency solar cells. Here, we present a robust and low-cost 1,2-ethanedithiol/ethanolamine/2-methoxyethanol ternary solution process to prepare Cu2ZnSnS4 precursor solution and high-quality Cu2ZnSnS4 thin films. Low-cost Cu2O, ZnO and SnO are used as the raw materials, which can be easily dissolved in the 2-methoxyethanol solution of 1,2-ethanedithiol and ethanolamine at room temperature in air. By tuning the composition of the Cu2ZnSn(S,Se)(4) thin film with a selenization process, an active-area power conversion efficiency of 7.34% has been achieved for Cu2ZnSn(S,Se)(4) solar cell

MoS2-C/graphite, an electric energy storage device using Na+-based organic electrolytes

Molybdenum disulfide-carbon composite (MoS2-C) sample has been prepared by a hydrothermal method using Na2MoO4, CH4N2S and glucose as starting materials and then calcined at 800 degrees C in an N-2/H-2 mixed atmosphere. X-ray diffraction and N-2 adsorption-desorption tests have been employed to characterize its crystal and pore structure. SEM, TEM and TG methods have been used to investigate its morphology and the weight ratio of carbon. The MoS2-C can be used as the negative electrode for electric energy storage devices using Na+-based organic electrolytes. The charge storage mechanism at the MoS2-C negative electrode has been investigated. Electric energy storage devices using MoS2-C/graphite have been constructed and their electrochemical performance has been studied

Multifunctional polyelectrolyte multilayers coated onto Gd2O3:Yb3+,Er3+@MSNs can be used as drug carriers and imaging agents

Mesoporous silica nanoparticles (MSNs) were firstly functionalized with upconversion luminescent Gd2O3:Yb3+, Er3+ via the Pechini sol-gel method. Then, polyelectrolyte multilayers (PEM) composed of poly(allyamine hydrochloride) (PAH) and poly(styrene sulfonate) (PSS) were coated onto the Gd2O3:Yb3+, Er3+@MSNs using a layer-by-layer (LbL) technique to achieve the pH-responsive properties of the nanocarriers. PEM@Gd2O3:Yb3+, Er3+@MSNs loaded with doxorubicin hydrochloride (DOX) showed pH-responsive release and higher cytotoxicity towards MCF-7 breast cancer cells in vitro. Nanocomposites functionalized with Gd2O3:Yb3+, Er3+ can serve as T-1-weighted magnetic resonance imaging (MRI) contrast agents. Nanoparticles emitting red signals under 980 nm laser excitation are suitable for use in potential bioimaging applications. The upconversion luminescent (UCL) intensity of PEM-coated nanocomposites can be adjusted by controlling the number of layers of the PAH/PSS coating. The PEM@Gd2O3:Yb3+, Er3+@MSNs can be used as a potential drug delivery system for MRI, UCL imaging, and pH-responsive chemotherapy

New deep-red heteroleptic iridium complex with 3-hexylthiophene for solution-processed organic light-emitting diodes emitting saturated red and high CRI white colors

The exploitation of soluble and efficient deep-red phosphorescent emitters is of paramount importance for solution-processed organic light-emitting diodes (OLEDs) applied in both high-quality RGB displays and high color-rendering-index (CRI) solid-state lighting source. In this work, a new deep-red heteroleptic iridium(III) complex, i.e. bis[2,5-di(4-hexylthiophen-2-yl)pyridine][acetylacetonate] iridium(III) [Ir(ht-5ht-py)(2)(acac)], has been synthesized and successfully used to fabricate solution-processed saturated red and white organic light-emitting diodes (WOLEDs). The long alkyl side-chains of Ir(ht-5ht-py)(2)(acac) render its excellent solubility in common organic solvents and good compatibility with common host materials. The solution-processed red OLED based on Ir(ht-5ht-py)(2)(acac) exhibited a decent external quantum efficiency of 8.2% and a power efficiency of 6.5 lm/W, with satisfactory Commission International de L'Eclairage (CIE) coordinates of (0.68, 0.31) for saturated red emission. Furthermore, the prepared multiple-phosphors-doped WOLED with Ir(ht-5ht-py)(2)(acac) as the red emitter showed an excellent high color rendering index (CRI) value of 89 as well as low color-correlated temperature (CCT) of 2331 K, which can meet the call for physiologically-friendly indoor illumination. (C) 2015 Elsevier B.V. All rights reserved

Spheres-on-sphere silica microspheres as matrix for horseradish peroxidase immobilization and detection of hydrogen peroxide

In this work, spheres-on-sphere (SOS) silica microspheres are prepared via a facile one-pot synthesis. After functionalization with carboxyl groups, the carboxylated SOS silica microspheres (SOS-COOH microspheres) can serve as a support for horseradish peroxidase (HRP) covalent immobilization. The obtained enzyme hybrid (SOS-COOH-HRP) is more stable under alkaline conditions than the free counterpart, and exhibits longer-term storage stability and higher resistance toward the denaturing agents such as guanidine hydrochloride (GdmCl) and urea. The Michaelis-Menten constant (K-m) of the immobilized enzyme is decreased slightly while the maximum rate of reaction (V-max) is very close to that of free HRP, resulting in the catalytic efficiency of SOS-COOH-HRP being enhanced significantly. For evaluating its utility, a SOS-COOH-HRP-based colorimetric method has been developed for selectively and sensitively detecting H2O2 both in buffer and 10% diluted human serum. Furthermore, the SOS-COOH-HRP displays excellent reusability and reproducibility in cycle analysis. The results demonstrate that the SOS-COOH-HRP has great potential for practical applications in biosensing and industrial fields

One-step synthesis of an urchin-like sulfur/polyaniline nano-composite as a promising cathode material for high-capacity rechargeable lithium-sulfur batteries

An urchin-like sulfur/polyaniline (S/PANI) nano-composite has been synthesized by a very soft and facile approach. This novel composite could be directly utilized as the cathode material for lithium-sulfur (Li-S) batteries and displays high specific capacity at different discharge current densities and good stability over long-term cycling

Growth Behavior of Initial Product Layer Formed on Mg Alloy Surface Induced by Polyaniline

The quality of the interfacial protective layer induced by polyaniline (PAN!) has been claimed to play a crucial role for the enhanced corrosion protection of Mg alloy, but its growth behavior is not well understood. Here some composition. structure and growth kinetics of the protective layer formed at the PANI-emeraldine base (EB) coating/AZ91D Mg alloy interface were investigated to explore the growth mechanism. Upon immersion in 0.5 M NaCl solution, the growing interface layer under EB coating exhibited a fast passivation rate and an increased corrosion resistance, which was largely influenced by ion concentration. XPS depth profiles showed that the EB-induced layer was a mixture of MgO and Mg(OH)(2), in which no significant bi-layer structure existed and MgO was dominant throughout the bulk film. These observations suggest that the interaction between EB and Mg can promote the faster growth of a stable MgO-rich layer mixed with Mg(OH)(2) probably by solid reaction. Meanwhile less hydration of MgO and dissolution-precipitation reaction occur, thus leading to less Mg(OH)(2) in the outer layer. (C) The Author(s) 2015. Published by ECS. This is an open access article distributed under the terms of the Creative Commons Attribution 4.0 License (CC BY, http://creativecommons.org/licensestby/4.0/), which permits unrestricted reuse of the work in any medium, provided the original work is properly cited. All rights reserved