Efficient Regioselective Synthesis of the Crotonyl Polydatin Prodrug by <Emphasis Type="Italic">Thermomyces lanuginosus</Emphasis> Lipase: a Kinetics Study in Eco-friendly 2-Methyltetrahydrofuran

Bio-based solvents have recently been discussed as sustainable green and promising alternatives to conventional organic media for enzymatic processes. In this paper, highly regioselective synthesis of the 6″-O-crotonyl-polydatin catalyzed by Thermomyces lanuginosus lipase (TLL) in biomass-derived 2-methyltetrahydrofuran (2-MeTHF) was successfully performed for the first time. The results indicated that TLL lipase displayed significantly improved catalytic performance in 2-MeTHF than in other traditional solvents. Under the optimal conditions, the initial reaction rate, 6″-regioselectivity, and maximum substrate conversion were as high as 12.38 mM h^?1, 100 %, and 100 %, respectively. Moreover, further investigations on the operational stability, kinetic parameters like V _max, K _m, V _max/K _m, and E _a revealed that 2-MeTHF exhibited excellent biocompatibility and rendered the greener process of the enzymatic acylation.     

Colorimetric detection of proteins based on target-induced activation of aptazyme

The detection of protein is vital to fundamental research as well as practical applications. However, most detection methods depend on antibody-based assays which are faced with many shortcomings. Herein, we propose a colorimetric method for protein assays based on target-triggered activation of aptazyme, which may offer simple, rapid and cost-effective detection of the target protein. In this method, the conformation change of aptazyme induced by target protein is designed to be associated with aptazyme activation. Consequently, in the presence of the target protein, the designed DNA linkers will be cleaved into two fragments that fail to cross-link gold nanoparticles (GNPs), thus the color of GNP solution remains red, while the color will be changed in the absence of the target. Because of the advantages of aptazyme such as economic synthesis, stable, easy modification and its ability to accomplish signal recognition and signal amplification simultaneously, the method is thermostable, simple and cost-efficient. In this work, we have taken the detection of vascular endothelial growth factor (VEGF) as an example, which can present an analytical performance with as low as 0.1 nM detection limit, spanning a detection range of 3 orders of magnitude. What is more, the principle of this proposed new method can be extended as a universal assay method not only for the detection of analytes which have an aptamer but also for those analytes that have ligands.     

Use of an Octapeptide–Guanidiniocarbonylpyrrole Conjugate for the Formation of a Supramolecular β‐Helix that Self‐Assembles into pH‐Responsive Fibers

Peptides that adopt β‐helix structures are predominantly found in transmembrane protein domains or in the lipid bilayer of vesicles. Constructing a β‐helix structure in pure water has been considered difficult without the addition of membrane mimics. Herein, we report such an example; peptide 1 self‐assembles into a supramolecular β‐helix in pure water based on charge interactions between the individual peptides. Peptide 1 further showed intriguing transitions from small particles to helical fibers in a time‐dependent process. The fibers can be switched to vesicles by changing the pH value.     

"Microfluidic drifting"--implementing three-dimensional hydrodynamic focusing with a single-layer planar microfluidic device

We introduce a novel fluid manipulation technique named "microfluidic drifting" to enable three-dimensional (3D) hydrodynamic focusing with a simple single-layer planar microfluidic device.     

Stress relaxation in polymer networks: equilibrium behavior and dynamics

The elastic and relaxational properties of a polymer network have been calculated using a stress based formulation based on the Rouse mode expansion [W. L. Vandoolaeghe and E. M. Terentjev, J. Chem. Phys. 123, 34902 (2005)]. In this article, we propose an improved Rouse mode expansion incorporating appropriate boundary conditions. In contrast to the previous work, this improved formulation provides a smooth crossover from the classical equilibrium result of rubber elasticity to the shorter-time-scale Rouse relaxation of a polymer melt. Our results are compared with the classical phantom network approach in equilibrium, as well as both equilibrium and dynamic elongation experiments. The model captures the qualitative features of the data well and some of the quantitative aspects, such as the exponents seen in the dynamic modulus G(omega).     

Telluroxides exhibit hydrolysis capacity

It has long been known that tellurium compounds are rather toxic to living organisms, and tellurium has not been found in natural biomacromolecules to date. The principles of telluride toxicity in biological processes are still controversial partly because of the lack of information on the biochemical features of tellurium. In this contribution, we report our finding for the first time that telluroxides exhibit hydrolysis capacity. For instance, 6,6'-telluroxy-bis(6-deoxy-beta-cyclodextrin) acts as a hydrolase mimic and shows a significant rate acceleration of 106,000 for the hydrolysis of 4,4'-dinitrodiphenyl carbonate.     

糖及土豆淀粉水解液的鉴定——薄层层析法

1.掌握薄层层析实验方法 2.应用此方法进行糖及土豆淀粉水解液的鉴定。薄层层析是一种微量而快速的层析方法。此方法是将吸附剂在玻璃板上涂成薄层经干燥活化后,把待分析的样品溶液点到薄层上,然后用合适的溶剂展开,展开后再将薄层板取出晾干,喷显色剂及计算它们的Rf值就可将待测物质鉴定出来。     

Experimental Studies on Radiation Damages of CsI(Tl) Crystals

The results of experimental studies on eadiation damage of CsI(Tl) crystal were reported.There are radiation damage effects on CsI(Tl) crystal.Experimental studies on recovery of damaged CsI(Tl) crystals were made.It seems that after heating at 200℃ for 4 hours,the damaged crystals could be recovered completely.