Simultaneous determination of wogonin, oroxylin a, schisandrin, paeoniflorin and emodin in rat serum by HPLC-MS/MS and application to pharmacokinetic studies.

Wogonin and oroxylin A in Scutellariae Radix, schisandrin in Chinensis Fructus, paeoniflorin in Moutan Cortex and emodin in Polygoni Cuspidate Rhizome et Radix are anti-inflammatory active compounds. A method for simultaneous determination of the five compounds in rat was developed and validated using high-performance liquid chromatography with tandem mass spectrometry (HPLC-MS/MS). The separation was performed on a Symmetry C18 column (4.6 × 50 mm, 3.5 µm) with acetonitrile and 0.1% formic acid aqueous solution as the mobile phases. The detection was performed using multiple-reaction monitoring with electrospray ionization source in positive-negative ion mode. The calibration curves showed good linearity (r ≥ 0.9955). The lower limit of quantification (LLOQ) was 5 ng/mL for wogonin and schisandrin, 10 ng/mL for oroxylin A and emodin, and 15 ng/mL for paeoniflorin, respectively. The relative standard deviations of intraday and interday precisions were <11.49 and 14.28%, respectively. The extraction recoveries and matrix effects were acceptable. The analytes were stable under the experiment conditions. The validated method has been successfully applied to pharmacokinetic studies of the five compounds in rats after oral administration of Hu-gan-kan-kang-yuan capsule. This paper would be a valuable reference for pharmacokinetic studies of Chinese medicine preparations containing the five compounds.

Magnetoresistive polyaniline-silicon carbide metacomposites: plasma frequency determination and high magnetic field sensitivity.

The Drude model modified by Debye relaxation time was introduced to determine the plasma frequency (ωp) in the surface initiated polymerization (SIP) synthesized ß-silicon carbide (ß-SiC)/polyaniline (PANI) metacomposites. The calculated plasma frequency for these metacomposites with different loadings of ß-SiC nanoparticles was ranging from 6.11 × 10(4) to 1.53 × 10(5) rad s(-1). The relationship between the negative permittivity and plasma frequency indicates the existence of switching frequency, at which the permittivity was changed from negative to positive. More interestingly, the synthesized non-magnetic metacomposites, observed to follow the 3-dimensional (3-D) Mott variable range hopping (VRH) electrical conduction mechanism, demonstrated high positive magnetoresistance (MR) values of up to 57.48% and high MR sensitivity at low magnetic field regimes.

Optimal Electrocatalytic Pd/MWNTs Nanocatalysts toward Formic Acid Oxidation.

The operating conditions such as composition of electrolyte and temperature can greatly influence the formic acid (HCOOH) oxidation reaction (FAOR). Palladium decorated multi-walled carbon nanotubes (Pd/MWNTs) were successfully synthesized and employed as nanocatalysts to explore the effects of formic acid, sulfuric acid (H2SO4) concentration and temperature on FAOR. Both the hydrogen adsorption in low potential range and the oxidation of poisoning species during the high potential range in cyclic voltammetry were demonstrated to contribute to the enhanced electroactivity of Pd/MWNTs. The as-synthesized Pd/MWNTs gave the best performance under a condition with balanced adsorptions of HCOOH and H2SO4 molecules. The dominant dehydrogenation pathway on Pd/MWNTs can be largely depressed by the increased dehydration pathway, leading to an increased charge transfer resistance (Rct ). Increasing HCOOH concentration could directly increase the dehydration process proportion and cause the production of COads species. H2SO4 as donor of H+ greatly facilitated the onset oxidation of HCOOH in the beginning process but it largely depressed the HCOOH oxidation with excess amount of H+. Enhanced ion mobility with increasing the temperature was mainly responsible for the increased current densities, improved tolerance stabilities and reduced Rct values, while dehydration process was also increased simultaneously.

An overview of the magnetoresistance phenomenon in molecular systems.

In this review, the classification of magnetoresistance effects, the electrical conduction mechanisms without and with magnetic field, and the spintronics are briefly summarized. The magnetoresistance effect in the molecular systems including small organic molecules, carbon nanotubes, graphene, conductive polymers and their nanocomposites is critically reviewed. The four normally used models are elaborated to disclose the mechanisms of organic magnetoresistance (OMAR) in the organic systems. The most current applications of these molecular systems are also summarized. These molecular systems are envisioned to create next-generation spintronic and electronic devices for flexible applications.

Giant magnetoresistance in non-magnetic phosphoric acid doped polyaniline silicon nanocomposites with higher magnetic field sensing sensitivity.

Phosphoric acid doped conductive polyaniline (PANI) polymer nanocomposites (PNCs) reinforced with silicon nanopowders have been successfully synthesized using a facile surface initiated polymerization (SIP) method. The chemical structures of the nanocomposites are characterized using Fourier transform infrared (FT-IR) spectroscopy. The enhanced thermal stability of the silicon-PANI PNCs compared with pure PANI is obtained using thermogravimetric analysis (TGA). The obtained optical band gap of the PNCs using Ultraviolet-visible diffuse reflectance spectroscopy (UV-vis DRS) decreases with increasing silicon loading. The dielectric properties of the PNCs are strongly related to the silicon loading level. Temperature dependent resistivity analysis reveals a quasi 3-D variable range hopping (VRH) electrical conduction mechanism for the synthesized PNCs. Room temperature giant magnetoresistance (GMR) is observed in the synthesized non-magnetic nanocomposites and analyzed using the wave-function shrinkage model.

Carbon nanostructure-derived polyaniline metacomposites: electrical, dielectric, and giant magnetoresistive properties.

Polyaniline (PANI) nanocomposites incorporating different loadings of graphene and various other carbon nanostructures including carbon nanotubes (CNTs) and carbon nanofibers (CNFs) have been synthesized using a surface-initiated polymerization (SIP) method. Transmission electron microscopy (TEM) results indicate that the graphene has been exfoliated into a few layers (typically one, two, and three layers) during polymerization and has been uniformly dispersed in the PANI matrix. The graphene layer dispersion degree is quantified by a free-path spacing measurement (FPSM) method based on the TEM microstructures. The SIP method also demonstrates its feasibility for coating PANI on one-dimensional (1D) CNFs and CNTs without introducing additional surface functional groups. The effects of graphene size, loading level, and surface functionality on the electrical conductivity and dielectric permittivity of their corresponding nanocomposites have been systematically studied. The temperature-dependent conductivity behavior revealed a quasi-3D variable range hopping (VRH) electron transport mechanism for all the nanocomposites. Giant magnetoresistance (GMR) at room temperature is observed in pure PANI, which can be enhanced by the incorporation of a high loading of graphene (5%) due to the π-π stacking-induced efficient electron transport at the PANI/graphene interface. More interestingly, negative permittivity is found in each composite which can be easily tuned by adjusting the filler loading, morphology, and surface functionality.

One-pot synthesis of magnetic graphene nanocomposites decorated with core@double-shell nanoparticles for fast chromium removal.

A facile thermodecomposition process to synthesize magnetic graphene nanocomposites (MGNCs) is reported. High-resolution transmission electron microscopy and energy filtered elemental mapping revealed a core@double-shell structure of the nanoparticles with crystalline iron as the core, iron oxide as the inner shell and amorphous Si-S-O compound as the outer shell. The MGNCs demonstrate an extremely fast Cr(VI) removal from the wastewater with a high removal efficiency and with an almost complete removal of Cr(VI) within 5 min. The adsorption kinetics follows the pseudo-second-order model and the novel MGNC adsorbent exhibits better Cr(VI) removal efficiency in solutions with low pH. The large saturation magnetization (96.3 emu/g) of the synthesized nanoparticles allows fast separation of the MGNCs from liquid suspension. By using a permanent magnet, the recycling process of both the MGNC adsorbents and the adsorbed Cr(VI) is more energetically and economically sustainable. The significantly reduced treatment time required to remove the Cr(VI) and the applicability in treating the solutions with low pH make MGNCs promising for the efficient removal of heavy metals from the wastewater.

Modified solid-state reaction synthesized cathode lithium iron phosphate (LiFePO4) from different phosphate sources.

A modified solid-state method was used to prepare LiFePO4. With the aid of deionized water, a mixture containing Fe2O3, NH4H2PO4 (or (NH4)2HPO4), LiOH, glucose and oxalic acid was prepared into fluffy powders, which were heated in a carbon-coated crucible at 700 degrees C for 3 hours to synthesize LiFePO4 without any inert gas flow. For the first time, the roles of NH4H2PO4 and (NH4)2HPO4 on the preparation of LiFePO4 were systematically investigated. The obtained samples were characterized by X-ray diffraction (XRD), scanning electron microscope (SEM) and energy dispersive spectroscopy (EDS), revealing that the crystallinity of the LiFePO4 sample prepared from NH4H2PO4 is superior to that prepared from (NH4)2HPO4 and the particle size of the sample prepared from NH4H2PO4 is smaller than that prepared from (NH4)2HPO4. The specific capacity, cycle property and rate capabilities were also compared between the as-prepared LiFePO4 samples. A better electrochemical performance was observed in the sample prepared from NH4H2PO4.

The recent progress of synergistic supramolecular polymers: preparation, properties and applications.

Supramolecular polymers have the combined properties of both traditional polymers and supramolecules. They are generally formed via the self-assembled polymerization driven noncovalent interactions such as hydrogen bonding, π-π stacking, metal coordination, and host-guest interaction between building blocks. The driving force for the formation of supramolecular polymers has changed from single noncovalent interactions to multiple noncovalent interactions. The advantages of multiple noncovalent interactions driving the formation of supramolecular polymers are reviewed from four aspects: polymer construction, the enhancement of bonding strength, properties and topological structure. The applications are illustrated with detailed examples including self-healing, drug delivery, bioimaging, biomedicine, environmental sensing and electronics.

Long-Term Effect against Methicillin-Resistant Staphylococcus aureus of Emodin Released from Coaxial Electrospinning Nanofiber Membranes with a Biphasic Profile.

Methicillin-resistant Staphylococcus aureus (MRSA) is a serious and rapidly growing threat to human beings. Emodin has a potent activity against MRSA; however, its usage is limited due to high hydrophobicity and low oral bioavailability. Thus, the coaxial electrospinning nanofibers encapsulating emodin in the core of hydrophilic poly (vinylpyrrolidone), with a hygroscopic cellulose acetate sheath, have been fabricated to provide long-term effect against MRSA. Scanning electron microscopy and transmission electron microscopy confirmed the nanofibers had a linear morphology with nanometer in diameter, smooth surface, and core-shell structure. Attenuated total reflection-Fourier transform infrared spectra, X-ray diffraction patterns, and differential scanning calorimetric analyses verified emodin existed in amorphous form in the nanofibers. The nanofibers have 99.38 ± 1.00% entrapment efficiency of emodin and 167.8 ± 0.20 % swelling ratio. Emodin released from nanofibers showed a biphasic drug release profile with an initial rapid release followed by a slower sustained release. CCK-8 assays confirmed the nontoxic nature of the emodin-loaded nanofibers to HaCaT cells. The anti-MRSA activity of the nanofibers can persist up to 9 days in AATCC147 and soft-agar overlay assays. These findings suggest that the emodin-loaded electrospun nanofibers with core-shell structure could be used as topical drug delivery system for wound infected by MRSA.

Carbon nitride nanoplatelet photocatalysts heterostructured with B-doped carbon nanodots for enhanced photodegradation of organic pollutants.

Decorating electron-accepting materials on carbon nitride (C3N4) is a promising strategy to construct heterostructure catalysts for improved photocatalytic abilities. In this study, B-doped carbon-dots (B-C-dots) decorated C3N4 (C3N4/B-C-dots) catalysts were fabricated through the surface deposition. The benefits from integration of B-C-dots and C3N4 are four folds: (i) increasing surface area; (ii) improving visible light absorption; (iii) promoting the transfer of photoinduced carriers; and (iv) reducing the recombination of photoinduced carriers. The optimum photocatalytic activity of B-C-dots/C3N4 for Rhodamine B (Rh B) (or tetracycline hydrochloride (TC)) degradation was about 7.21 (6.56) and 4.80 (4.35) times higher than that of C3N4 and C-dots/C3N4, respectively, exhibiting both remarkable stability and repeatability. Moreover, enhanced photocatalytic activity of C3N4/B-C-dots could also be attributed to the type-II heterojunction formed between C3N4 and B-C-dots caused by B doping.

Ion-imprinted thermosensitive chitosan derivative for heavy metal remediation.

Ion-imprinted thermosensitive chitosan derivative (ITC) was successfully synthesized through a novel gradient heating process towards applications in heavy metal remediation, using Cu2+ template paired with N-isopropylacrylamide (NIPAM) monomer. SEM, DSC, FTIR and Raman spectroscopy were used to characterize the structure and properties of ITC. The phase change temperature (PCT) of ITC was 35.31 °C in the heating cycle, whereas in the cooling cycle the PCT for ITC was 26.27 °C. The adsorption capacity of ITC for Cu2+ at 45 °C (> PCT) was 88.94 mg/g. Desorption rate of 98.90 % was achieved after washing with ultra-pure water at 20 °C (< PCT). An adsorption capacity of 85 mg/g and a desorption rate of 97 % sustained after five cycles reuse. The adsorption capacity for Cu2+ was measured at 80.23 mg/g under other seven interfering metal ions. The adsorption kinetics and adsorption isotherm fitted pseudo-second-order and Langmuir equation, respectively.

Magnetic nanocellulose-magnetite aerogel for easy oil adsorption.

HYPOTHESIS: Cellulose aerogels are a new category of high-efficiency adsorbents for treating oil spills and water pollution. However, the hydrophilic properties and recyclability of aerogels after adsorption hamper developments and applications. Combining both hydrophobic and magnetic properties are expected to improve their adsorption capacity and functionality. EXPERIMENTS: In this study, the effect of oleic acid (OA) and nanomagnetite on the preparation of magnetic nanocellulose aerogels (called as NCA/OA/Fe3O4) by a mechanical mixing combined with freeze-drying method have been investigated. FINDINGS: It has been found that the optimal condition for fabricating this NCA/OA/Fe3O4 aerogel is 0.4 wt% nanocellulose, 3 mg mL-1 OA and 0.5 wt% Fe3O4 in the aqueous solution. This aerogel has a very low density of 9.2 mg cm-3 and demonstrates a high adsorption capacity of 68.06 g g-1 for cyclohexane. In addition, this aerogel adsorbent demonstrates an excellent magnetic responsivity and can be easily recycled by a permanent magnet after adsorption. As a consequence, this hydrophobic magnetic NCA/OA/Fe3O4 aerogel is promising not only for easy oil and organic solvent adsorption but also potentially for other magnetic related applications.

Controllable organic magnetoresistance in polyaniline coated poly(p-phenylene-2,6-benzobisoxazole) short fibers.

Herein, we first report a tunable organic magnetoresistance (OMAR) effect in polyaniline (PANI) coated acid treated poly(p-phenylene-2,6-benzobisoxazole) (t-PBO) short fibers. This unique OMAR is interpreted using the paramagnetic nature of PBO molecules combined with the localization length a0 calculated from the wave-function shrinkage model and forward interference model.

Coaxial electrospun fibers: applications in drug delivery and tissue engineering.

Coelectrospinning and emulsion electrospinning are two main methods for preparing core-sheath electrospun nanofibers in a cost-effective and efficient manner. Here, physical phenomena and the effects of solution and processing parameters on the coaxial fibers are introduced. Coaxial fibers with specific drugs encapsulated in the core can exhibit a sustained and controlled release. Their exhibited high surface area and three-dimensional nanofibrous network allows the electrospun fibers to resemble native extracellular matrices. These features of the nanofibers show that they have great potential in drug delivery and tissue engineering applications. Proteins, growth factors, antibiotics, and many other agents have been successfully encapsulated into coaxial fibers for drug delivery. A main advantage of the core-sheath design is that after the process of electrospinning and release, these drugs remain bioactive due to the protection of the sheath. Applications of coaxial fibers as scaffolds for tissue engineering include bone, cartilage, cardiac tissue, skin, blood vessels and nervous tissue, among others. A synopsis of novel coaxial electrospun fibers, discussing their applications in drug delivery and tissue engineering, is covered pertaining to proteins, growth factors, antibiotics, and other drugs and applications in the fields of bone, cartilage, cardiac, skin, blood vessel, and nervous tissue engineering, respectively. WIREs Nanomed Nanobiotechnol 2016, 8:654-677. doi: 10.1002/wnan.1391 For further resources related to this article, please visit the WIREs website.

Manipulating the dimensional assembly pattern and crystalline structures of iron oxide nanostructures with a functional polyolefin.

Controlled crystalline structures (α- and γ-phase) and assembly patterns (1-D, 2-D and 3-D) were achieved in the synthesized iron oxide (Fe2O3) nanoparticles (NPs) using polymeric surfactant-polypropylene grafted maleic anhydride (PP-g-MA) with different concentrations. In addition, the change of the crystalline structure from the α- and γ-phase also led to the significantly increased saturation magnetization and coercivity.

Photochemically patterned poly(methyl methacrylate) surfaces used in the fabrication of microanalytical devices.

We report here the photochemical surface modification of poly(methyl methacrylate), PMMA, microfluidic devices by UV light to yield pendant carboxylic acid surface moieties. Patterns of carboxylic acid sites can be formed from the micrometer to millimeter scale by exposure of PMMA through a contact mask, and the chemical patterns allow for further functionalization of PMMA microdevice surfaces to yield arrays or other structured architectures. Demonstrated here is the relationship between UV exposure time and PMMA surface wettability, topography, surface functional group density, and electroosmotic flow (EOF) of aqueous buffer solutions in microchannels made of PMMA. It is found that the water contact angle on PMMA surfaces decreases from 70 degrees to 24 degrees after exposure to UV light as the result of the formation of carboxylic acid sites. However, upon rinsing with 2-propanol, the water contact angle increases to approximately 80 degrees , and this increase is attributed to changes in surface roughness resulting from removal of low molecular weight PMMA formed from scission events. In addition, the surface roughness and surface coverage of carboxylic acid groups exhibit a characteristic trend with UV exposure time. Electroosmotic flow (EOF) in PMMA microchannels increases upon UV modification and is pH dependent. The possible photolysis mechanism for formation of carboxylic acid groups on PMMA surfaces under the conditions outlined in this work is discussed.

Multifunctional Carbon Nanostructures for Advanced Energy Storage Applications.

Carbon nanostructures-including graphene, fullerenes, etc.-have found applications in a number of areas synergistically with a number of other materials. These multifunctional carbon nanostructures have recently attracted tremendous interest for energy storage applications due to their large aspect ratios, specific surface areas, and electrical conductivity. This succinct review aims to report on the recent advances in energy storage applications involving these multifunctional carbon nanostructures. The advanced design and testing of multifunctional carbon nanostructures for energy storage applications-specifically, electrochemical capacitors, lithium ion batteries, and fuel cells-are emphasized with comprehensive examples.

Ultrafine FePd Nanoalloys Decorated Multiwalled Cabon Nanotubes toward Enhanced Ethanol Oxidation Reaction.

Ultrafine iron-palladium (FePd) nanoalloys deposited on γ-Fe2O3, FePd-Fe2O3, further anchored on carboxyl multiwalled carbon nanotubes (MWNTs-COOH), FePd-Fe2O3/MWNTs, were successfully synthesized by a facile one-pot solution based method as thermally decomposing palladium acetylacetonate (Pd(acac)2) and iron pentacarbonyl (Fe(CO)5) in a refluxing dimethylformamide solution in the presence of MWNTs-COOH. A 3.65 fold increase of peak current density was observed in cyclic voltammetry (CV) for ethanol oxidation reaction (EOR) compared with that of Pd/MWNTs after normalizing to Pd mass. The greatly enhanced tolerance stability toward poisoning species and largely reduced charge transfer resistance were also obtained in chronoamperometry and electrochemical impedance spectroscopy due to the downward shifted d-band center of FePd alloy, easily formed oxygen containing species on Fe2O3, and the stabilizing role of the MWNTs.