AFM and fluorescence spectrascopy investigation for disaggregation of existing Aβ fibrils by baicalein

The wavelength for the peak of fluorescence emission of thioflavin T（ThT） was changed from 445 nm to 481 nm when ThT was added in Aβ solution which indicating theβ-sheet structure of Aβ fibril.The significant decrease in the intensity of fluorescence at 481 nm was observed when the baicalein was added in mixed solution of Aβ and ThT,suggesting that the depolymerization of Aβ fibrils happened and there were Aβfibrils left to react with ThT to keep the initial fluorescence intensity.And the existing Aβfibrils are disaggregated by baicalein in a time- and dose-dependent manner.AFM images of the morphologies of the Aβ_1-42 fibrils obviously changed smaller and more dispersive when baicalein added indicating also the depolymerization of Aβ.The results demonstrate a basis for development of a potential herb drug candidate for the treatment of Alzheimer’s disease（AD）.     

Rapid hydrolysis of phosphate ester promoted by Ce(IV) conjugating with a β-cyclodextrin monomer and dimer

Two N-donor ligands (L(1) and L(2)) derived from a β-cyclodextrin (βCD) monomer and dimer were employed to mediate the hydrolytic activity and stability of the Ce(IV) ion in aqueous solution. Complexes Ce(IV)-L(1) and Ce(IV)-L(2) were prepared in situ and characterized by means of UV-vis and NMR measurements. Ce(IV)-L(1) catalyzed the hydrolysis of a DNA model, bis(4-nitrophenyl)phosphate (BNPP) with k(cat) = 5.2 × 10(-3) s(-1) (half-life t(1/2) ≈ 2 minutes) under mild conditions, which represented an approximate 130 million-fold acceleration with respect to the spontaneous hydrolysis of BNPP. The dinuclear species, [Ce(2)L(1)(2)(OH)(5)](3+), contributed splendidly to the catalytic efficiency which echoed the active species postulation of [Ce(2)(OH)(7)](+) in the literature. Ce(IV)-L(2) exhibited efficient binding with BNPP giving 1/K(M) = 2.1 × 10(5) M(-1) which exceeded other Ce(IV) species, e.g. [Ce(4)(OH)(15)](+), by 2 orders of magnitude, which highlighted the hydrophobicity effect of βCDs. Such a highly binding affinity leads to the second-order rate constant, k(cat)/K(M) = 2.3 × 10(2) M(-1) s(-1), which probably ranks as the highest in the non-enzymatic cleavage of BNPP under similar conditions. Additionally, Ce(IV)-L(2) showed favorable tolerance to basic aqua owing to the bulky protection of double βCD pendants.     

Understanding thermodynamic competitivity between biopolymer folding and misfolding under large-scale intermolecular interactions

Cooperativity is a hallmark of spontaneous biopolymer folding. The presence of intermolecular interactions could create off-pathway misfolding structures and suppress folding cooperativity. This raises the hypothesis that thermodynamic competitivity between off-pathway misfolding and on-pathway folding may intervene with cooperativity and govern biopolymer folding dynamics under conditions permitting large-scale intermolecular interactions. Here we report direct imaging and theoretical modeling of thermodynamic competitivity between biopolymer folding and misfolding under such conditions, using a two-dimensional array of proton-fueled DNA molecular motors packed at the maximal density as a model system. Time-resolved liquid-phase atomic force microscopy with enhanced phase contrast revealed that the misfolding and folding intermediates transiently self-organize into spatiotemporal patterns on the nanoscale in thermodynamic states far away from equilibrium as a result of thermodynamic competitivity. Computer simulations using a novel cellular-automaton network model provide quantitative insights into how large-scale intermolecular interactions correlate the structural dynamics of individual biomolecules together at the systems level.     

Investigation of the toxic effect of a QDs heterojunction on the interactions between small molecules and plasma proteins by fluorescence and resonance light-scattering spectra

The effect of a ZnO#ZnS QDs heterojunction (O#SQDs) on the binding affinities of flavonoid glycosides for bovine serum albumin (BSA) was investigated. The fluorescence intensities of BSA decreased remarkably with increasing concentration of O#SQDs. The magnitudes of the binding constants of flavonoid glycosides for BSA in the presence of O#SQDs were in the range of 10(5)-10(7) L mol(-1), and the number of binding sites per BSA (n) was determined as 1.24 ± 0.17. O#SQDs increased the affinities of flavonoid glycosides for BSA by about 2.96% to 114.68% depending on their structures. O#SQDs in blood will enhance the transportation of flavonoid glycosidegs in blood and improve their pharmacology effects. From this point, O#SQDs are a perfect candidate for flavonoid glycosides delivery applications.     

Spectrophotometric detection of tyrosinase activity based on boronic acid-functionalized gold nanoparticles

A spectrophotometric method for the detection of tyrosinase activity is developed by utilizing the product-triggered aggregation of boronic acid-functionalized gold nanoparticles. Based on the changes of absorbance in UV-visible spectra, the assay shows extremely high sensitivity and lowered limit of detection of 1 × 10(-10) u mL(-1).     

Carbon‐Decorated Single‐Crystalline Ni2P Nanotubes Derived from Ni Nanowire Templates: A High‐Performance Material for Li‐Ion Batteries

Single‐crystalline Ni₂P nanotubes (NTs) were facilely synthesized by using a Ni nanowire template. The mechanism for the formation of the tubular structures was related to the nanoscale Kirkendall effect. These NTs exhibited a core/shell structure with an amorphous carbon layer that was grown in situ by employing oleylamine as a capping agent. Galvanostatic charge/discharge measurements indicated that these Ni₂P/C NTs exhibited superior high‐rate capability and good cycling stability. There was still about 310 mAh g^?1 retained after 100 cycles at a rate of 5 C. Importantly, the tubular nanostructures and the single‐crystalline nature of the Ni₂P NTs were also preserved after prolonged cycling at a relatively high rate. These improvements were attributed to the stable nanotubular structure of Ni₂P and the carbon shell, which enhanced the conductivity of Ni₂P, suppressed the aggregation of active particles, and increased the electrode stability during cycling.     

Syntheses, crystal structures and luminescent properties of new lanthanide(III) organoarsonates

The first examples of lanthanide(III) organoarsonates, Ln(L(1))(H(2)O)(3) (Ln = La (1), H(3)L(1) = 4-hydroxy-3-nitrophenylarsonic acid), Ln(L(1))(H(2)O)(2) (Ln = Nd (2), Gd (3)), and mixed-ligand lanthanide(III) organoarsonates, Ln(2)(HL(1))(2)(C(2)O(4))(H(2)O)(2) (Ln = Nd (4), Sm (5), Eu (6)), were hydrothermally synthesized and structurally characterized. Compounds 1-3 feature a corrugated lanthanide arsonate layer, in which 1D lanthanide arsonate inorganic chains are further interconnected via bridging L(1)(3-) ligands. Compounds 4-6 exhibit a complicated 3D network. The interconnection of the lanthanide(III) ions by the bridging arsonate ligand leads to the formation of a novel 3D framework with long narrow 1D tunnels along the a-axis, with the oxalate anions are located at the above tunnels and bridging with lanthanide(III) ions. Compounds 2 and 4 exhibit the characteristic emission bands of the Nd(III) ion, whereas compound 6 displays the characteristic emission bands of the Eu(III) ion. The magnetic properties of compounds 3-6 were also investigated.     

Preparation of non-oriented silicon steel with high magnetic induction using columnar grains

Columnar grains can lead to detrimental surface ridging and an inhomogeneous microstructure, although their {1 0 0}〈0 v w〉 texture is considered desirable due to their good magnetic properties in non-oriented silicon steel. Based on the hereditary tendency of {1 0 0}〈0 v w〉 texture, the effects of lubrication and heating rate on texture and on final magnetic properties were investigated using a cast slab containing 100% columnar grains. Hot rolling with lubrication, normalization at low heating rate, two-stage cold rolling, and final annealing at 1000 °C helped achieve high performance. As a result, a new non-oriented silicon steel with high magnetic induction (B₅₀=1.82 T) and low core loss (P_1.5=2.35 W/kg) was prepared. The possibility of further performance optimization was also discussed.     

Conductivity exponent in three-dimensional percolation by diffusion based on molecular trajectory algorithm and blind-ant rules

Diffusion on random systems above and at their percolation threshold in three dimensions is carried out by a molecular trajectory method and a simple lattice random walk method, respectively. The classical regimes of diffusion on percolation near the threshold are observed in our simulations by both methods. Our Monte Carlo simulations by the simple lattice random walk method give the conductivity exponent μ/ν=2.32±0.02 for diffusion on the incipient infinite clusters and μ/ν=2.21±0.03 for diffusion on a percolating lattice above the threshold. However, while diffusion is performed by the molecular trajectory algorithm either on the incipient infinite clusters or on a percolating lattice above the threshold, the result is found to be μ/ν=2.26±0.02. In addition, it takes less time step for diffusion based on the molecular trajectory algorithm to reach the asymptotic limit comparing with the simple lattice random walk.