Electrospun composite nanofibrous membrane as wound dressing with good adhesion

A photopolymerizationable mimic mussel protein structure monomer, dopamine methacrylamide (DMA), was synthesized. The photopolymerization of DMA was analysed by series real time near infrared spectroscopy (SRTIR). Dopamine methacrylamide/poly (ethylene oxide) (DMA/PEO) nanofibers were successfully prepared by electrospinning of aqueous DMA/PEO solution. Biocompatible nanofibrous membrane with good adhesion was produced by photocuring from the DMA/PEO nanofibers. The surface characterization and structure of the composite nanofibrous membrane were characterized by a scanning electron microscopy (SEM) and contact angle measurements. For identifying the potential crystalline of curing, a XRD method was used through comparing diffraction data. In the cell adhesion test we utilized the mouse fibroblast (L929) to exam the various use of the nanofibrous membrane as scaffolding materials for skin regeneration.     

Preparation and application of molecularly imprinted polymer solid‐phase microextraction fiber for the selective analysis of auxins in tobacco

As signal molecules, auxins play an important role in mediating plant growth. Due to serious interfering substances in plants, it is difficult to accurately detect auxins with traditional solid‐phase extraction methods. To improve the selectivity of sample pretreatment, a novel molecularly imprinted polymer ‐coated solid‐phase microextraction fiber, which could be coupled directly to high‐performance liquid chromatography, was prepared with indole acetic acid as template molecule for the selective extraction of auxins. The factors influencing the polymer formation, such as polymerization solvent, cross‐linker, and polymerization time, were investigated in detail to enhance the performance of indole acetic acid‐molecularly imprinted polymer coating. The morphological and chemical stability of this molecularly imprinted polymer‐coated fiber was characterized by scanning electron microscopy, infrared spectrometry, and thermal analysis. The extraction capacity of the molecularly imprinted polymer‐coated solid‐phase microextraction fiber was evaluated for the selective extraction of indole acetic acid and indole‐3‐pyruvic acid followed by high‐performance liquid chromatography analysis. The linear range for indole acetic acid and indole‐3‐pyruvic acid was 1–100 µg/L and their detection limit was 0.5 µg/L. The method was applied to the simultaneous determination of two auxins in two kinds of tobacco (Nicotiana tabacum L and Nicotiana rustica L) samples, with recoveries range from 82.1 to 120.6%.     

Phenyl and Phenylethyl Glycosides from Picrorhiza scrophulariiflora

Three new phenyl glycosides, scrophenoside A ( 1 ), B ( 2 ), and C ( 3 ), and two new phenylethyl glycosides, scroside D ( 4 ) and scroside E ( 5 ), were isolated from the stem of Picrorhiza scrophulariiflora Pennell (Scrophularlaceae), besides five known compounds. On the basis of spectroscopic evidence, the structures of the new compounds were elucidated as 4‐acetyl‐2‐methoxyphenyl 6‐O‐[4‐(β‐D ‐glucopyranosyloxy)vanilloyl]‐β‐D ‐glucopyranoside ( 1 ), 4‐acetylphenyl 6‐O‐[(E)‐p‐coumaroyl]‐β‐D ‐glucopyranoside ( 2 ), 4‐[(1R)‐ and (1S)‐1‐hydroxyethyl]‐2‐methoxyphenyl β‐D ‐glucopyranoside ( 3a and 3b , resp.), 2‐(3,4‐dihydroxyphenyl)ethyl O‐β‐D ‐glucopyranosyl‐(1→3)‐4‐O‐[(E)‐feruloyl]‐β‐D ‐glucopyranoside ( 4 ), and 2‐(3,4‐dihydroxyphenyl)ethyl O‐β‐D ‐glucopyranosyl‐(1→3)‐6‐O‐[(E)‐feruloyl]‐β‐D ‐glucopyranoside ( 5 ).     

Investigation of the effects of Au-colloid modification on cobalt hexacyanoferrate film growth and mass transport by electrochemical quartz crystal microbalance

The growth of cobalt hexacyanoferrate (CoHCF) films on bare and Au-colloid-modified electrodes in nitrate or sulfate solutions was monitored by electrochemical quartz crystal microbalance. The average efficiency of CoHCF film growth for Au colloid modified electrodes is 23 and 12 ng cm(-2) s(-1) in KNO3 and K2SO4 solutions, respectively, while those values for the bare gold electrode are 15 and 9 ng cm(-2) s(-1), respectively. In K2SO4 solution, the apparent molar masses for the Au-colloid-modified electrode at lower and higher potential is 58.4 and 37.3 g mol(-1), respectively, which is larger than those for the bare gold electrode (51.7 and 26.3 g mol(-1), respectively). The respective results were also obtained in KNO3 solution. Furthermore, the difference of the apparent molar masses at lower and higher potential for Au-colloid-modified electrodes is smaller than that for bare gold electrodes in the same electrolyte. Additionally, the mechanism of charge propagation is dependent on different anions in electrolyte solutions at higher potentials where the second redox reaction of CoHCF occurs. Therefore, the existence of Au colloids can accelerate CoHCF film growth and weaken the effect of anions on mass transport.     

A novel azide-free asymmetric synthesis of oseltamivir phosphate (Tamiflu) starting from Roche’s epoxide

A novel azide-free asymmetric synthesis of oseltamivir phosphate 1 (Tamiflu®) starting from Roche’s epoxide is described. Roche epoxide 2 was converted into N-acetyl aminoalcohol 3 in 95% yield via a BF₃·OEt₂-catalyzed epoxide-opening with acetonitrile as a nucleophile. Compound 3 was then transformed into a methanesulfonate 4 in 98% yield. Compound 4 was converted into aziridine 5 in 91% yield. Aziridine 5 was subsequently converted into oseltamivir phosphate 1 via two paths (a and b). In the path a, compound 5 underwent aziridine-opening with diallylamine as a nucleophile to afford compound 7 in 93% yield; compound 7 could then be converted into oseltamivir phosphate 1 in 88% yield. In path b, compound 5 underwent aziridine-opening with isopropyl 2,2,2-trichloroacetimidate as a nucleophile to afford compound 8 in 94% yield, which was then converted into oseltamivir phosphate 1 in 82% yield.     

Controllable transport of water through nanochannel by rachet-like mechanism

By using molecular dynamics simulation, we have investigated systematically the feasibility of continuous unidirectional water flux across a deformed single-walled carbon nanotube (SWNT) driven by an oscillating charge outside without osmotic pressure or hydrostatic drop. Simulation results indicate that the flux is dependent sensitively on the oscillating frequency of the charge, the distance of the charge from the SWNT, and the asymmetry of the water-SWNT system. A resonance-like phenomenon is found that the water flux is enhanced significantly when the period of the oscillation is close to twice the average hopping time of water molecules inside the SWNT. These findings are helpful in developing a novel design of efficient functional nanofluidic devices.     

Self-assembly of inorganic nanoparticle vesicles and tubules driven by tethered linear block copolymers

Controllable self-assembly of nanoscale building blocks into larger specific structures provides an effective route for the fabrication of new materials with unique optical, electronic, and magnetic properties. The ability of nanoparticles (NPs) to self-assemble like molecules is opening new research frontiers in nanoscience and nanotechnology. We present a new class of amphiphilic "colloidal molecules" (ACMs) composed of inorganic NPs tethered with amphiphilic linear block copolymers (BCPs). Driven by the conformational changes of tethered BCP chains, such ACMs can self-assemble into well-defined vesicular and tubular nanostructures comprising a monolayer shell of hexagonally packed NPs in selective solvents. The morphologies and geometries of these assemblies can be controlled by the size of NPs and molecular weight of BCPs. Our approach also allows us to control the interparticle distance, thus fine-tuning the plasmonic properties of the assemblies of metal NPs. This strategy provides a general means to design new building blocks for assembling novel functional materials and devices.     

Recognition of Guanine by a Designed Triazine-based Fluorescent Probe through Intermolecular Multiple Hydrogen Bonding

A new fluorescent probe with a long-wavelength emission and multiple hydrogen bond sites for guanine, 3-(4-chloro-6-p-nitrophenoxy-1,3,5-triazinylamino)-7-dimethylamino-2-methylphenazine (CNTDP), was designed and synthesized by using cyanuric chloride as a molecular scaffold, neutral red as a fluorophore and p-nitrophenol as an assistant unit. The recognition behavior of CNTDP for guanine and its spectroscopic properties in different solvents were investigated. It was found that the probe's fluorescence can be selectively quenched by guanine instead of thymine, indicating that fully complementary hydrogen bonding plays a key role in such a recognition process. In addition, the fluorescence quenching mechanism of the probe by guanine and the electronic effects of neutral red, triazine ring and p-nitrophenol moieties on the fluorescence of the whole molecule were also discussed.     

A modified program for computation of formation constants of synergetic extraction complexes with two-phase titrations by using the Marquardt-Fletcher algorithm

A modified computer program SCTPT for the computation of formation constants of extraction complexes with two-phase pH titration data by using the Marquardt-Fletcher algorithm is described. It can be used to deal with extraction systems which consist of a metal, an acidic extractant and a neutral synergistic reagent with no need of new subroutine. It has been applied successfully to the Pb-PMBP(1-phenyl-3-methyl-4-benzoyl-pyrazolone-5)-TBP (tributyl phosphate) system. The results obtained are in agreement with those published in the literature.     

Electropolymerized m-phenylenediamine as a means to immobilize active protein on thickness-shear-mode quartz crystal

Electropolymerized m-phenylenediamine was used as an active coating for immobilizing urease and lectin on a gold-plated thickness-shear-mode (TSM) crystal. To enhance effectiveness of immobilization. a bilayer polymer film composed of polyaniline and poly-m-phenylenediamine was proposed. Compared with single poly-m-phenylenediamine film, the bilayer polymer film gave better results in terms of immobilizing capacity, stability and reproductivity. On this bilayer-film-coated TSM quartz crystal, the amount of immobilized lectin was estimated about 1.8 mug/cm(2). Detection of purified human erythrocytes is demonstrated as an example of potential application of this lectin-modified TSM biosensor in clinic.