Simple enzyme reactors suitable for the byproduct-free preparation of the aglycones of naturally occurring glycosides under mild conditions

Naringinase from Penicillium species—containing α-l-rhamnosidase and β-d-glucosidase activity—immobilized on silicate carriers can be used as a mild and effective means to cleave naturally occurring glycosides into their aglycones and sugar components. The procedure was tested with flavonoid-, anthraquinone-, and steroidglycosides. Since the solubility of such compounds is limited in aqueous solutions, a simple batch procedure has been developed to convert solid substrates suspended in only small amounts of buffer to the desired products with high yields.     

Preparation and application of monolithic columns with narrow immobilized pH gradients

Monolith with immobilized pH gradient (M-IPG) is a novel separation matrix for amphoteric substances, such as peptides and proteins. To improve the properties of the newly designed column, efforts were made to optimize the preparation procedure, including the concentrations of the monomers, glycidyl methacrylate (GMA) and ethylene glycol dimethacrylate (EDMA), as well as the kinds of porogens, which led to a monolith with improved permeability, uniformity and continuity. In addition, different diamines, including ethylenediamine, 1,3-diaminopropane, 1,4-diaminobutane and 1,5-diaminopentane, were subjected to aminate the polymer, and the last two exhibited excellent reactivity with epoxy on the polymer surface, which could obviously make the immobilization of pH gradient facilitated. Under the optimal conditions, a simple method to prepare M-IPG column with narrow pH gradient was developed with commercial carrier ampholytes (CAs) solution. Such columns were applied into the analysis of proteins and peptides, and showed the improved resolution compared to the traditional one with a wide pH distribution.     

Temperature-dependent behavior of immobilized alkaline phosphatase II. temperature pulse

The specific activity of immobilized alkaline phosphatase can be considerably increased by exposure to a brief temperature pulse. The thus-pulsed preparations show a hysteresis of higher activity at room temperature varying from 10 min to several days, depending upon their pretreatment and the conditions of the reaction mixture during the pulse. In almost all cases the pulse can be repeated many times to increase the activity.     

Sample Preparation of Energy Materials for X‐ray Nanotomography with Micromanipulation

X‐ray nanotomography presents an unprecedented opportunity to study energy storage/conversion materials at nanometer scales in three dimensions, with both elemental and chemical sensitivity. A critical step in obtaining high‐quality X‐ray nanotomography data is reliable sample preparation to ensure that the entire sample fits within the field of view of the X‐ray microscope. Although focused‐ion‐beam lift‐out has previously been used for large sample (few to tens of microns) preparation, a difficult undercut and lift‐out procedure results in a time‐consuming sample preparation process. Herein, we propose a much simpler and direct sample preparation method to resolve the issues that block the view of the sample base after milling and during the lift‐out process. This method is applied on a solid‐oxide fuel cell and a lithium‐ion battery electrode, before numerous critical 3D morphological parameters are extracted, which are highly relevant to their electrochemical performance. A broad application of this method for microstructure study with X‐ray nanotomography is discussed and presented.     

ZIF-8材料的制备及应用进展

沸石咪唑酯骨架材料(Zeolitic Imidazolate Framework-8,ZIF-8)是由Zn（Ⅱ）与2-甲基咪唑配位自组装形成的多孔结晶材料,具有可调的孔径、高稳定的结构和催化活性等特点,近年来ZIF-8的制备和应用展现出巨大的潜力并引起了广泛关注。本文总结了目前ZIF-8的制备方法,在此基础上介绍了ZIF-8的形成机理及粒径调控方法,重点综述了ZIF-8及其复合材料在吸附分离、催化、生物医学等领域应用的研究进展,并展望了其应用前景与发展方向,以期为ZIF-8 的应用发展开拓新的思路。     

Preparation and properties of sclerotium rolfsii invertase immobilized on indion 48-R

Crude extracellular invertase fromSclerotium rolfsii, when coupled to glutaraldehyde activated Indion 48-R, retained 70–80% activity of the soluble enzyme. Immobilization resulted in a decrease in the pH and temperature optima but it increased the temperature stability. K_m and V_max also increased as a result of immobilization. Both soluble and immobilized invertase showed inhibition at high substrate concentrations. The bound enzyme showed excellent stability to repeated use and retained approx 90% of its initial activity after 8 cycles of use.     

碱金属与碱土金属在煤炭热转化过程中的影响研究进展

对比阐述了AAEMs在煤炭热转化过程的影响与作用,论述了催化气化中炭结构转变、碱金属形态变化、催化剂失活等过程。AAEMs是催化气化的催化剂,是活性炭制备过程的造孔剂,也是高AAEMs煤利用过程的有害组分,同样也是煤灰提铝过程的焙烧活化剂。AAEMs与炭相互作用影响炭的表面结构,进而影响气化剂在炭表面的吸附与反应,而AAEMs与炭的相互作用也会影响AAEMs的挥发与释放,耦合催化气化与煤灰资源化利用可以有效降低催化剂回收成本。通过对比认识AAEMs在煤炭热转化中的影响与作用,以期为AAEMs作用下煤炭热转化过程提供新思路与方法。     

几种生物柴油的制备及其流变学性能的比较

以六种常见的动植物油脂为原料,制备生物柴油并测定其脂肪酸甲酯分布、凝点和冷滤点值。以动态流变仪为主要研究手段,研究了六种生物柴油的流体性能及相关影响因素。结果表明,生物柴油的凝点和冷滤点值受其脂肪酸甲酯分布的影响,饱和脂肪酸甲酯含量高的生物柴油,其凝点和冷滤点值也相应较高。流变学测定实验表明,六种生物柴油样品的流体性能受温度和剪切速率的影响。在较低的剪切速率范围内表现为典型的非牛顿流体行为,而在较高的剪切速率下则表现为牛顿流体行为。当流体温度高于生物柴油的相变温度时,六种生物柴油的表观黏度无明显差别,说明在该温度条件下生物柴油的脂肪酸甲酯分布对其流体黏度值影响不大;当流体温度接近其相变温度时,生物柴油流体黏度出现突跃式升高且其突变温度高于其冷滤点温度。     

Temperature-dependent behavior of immobilized alkaline phosphatase. I. Role of working conditions and pH during coupling

Alkaline phosphatase from hog intestine was immobilized to controlled-pore glass under various conditions. The specific activity of the enzyme was not diminished by immobilization. The influence of temperature and pH on the behavior and the stability of the immobilized enzyme preparations is discussed and compared to that of the native enzyme.     

Preparation,characterization, and potential application of an immobilized glucose oxidase

A simple, one-step process, using 0.25Mp-benzoquinone dissolved in 20% dioxane at 50°C for 24 h was applied to the activation of polyacrylamide beads. The activated beads were reacted with glucose oxidase isolated fromAspergillus niger. The coupling reaction was performed in 0.1M potassium phosphate at pH 8.5 and 0–4°C for 24 h. The protein concentration was 50 mg/mL. In such conditions, the highest activity achieved was about 100 U/g solid. The optimum pH for the catalytic activity was shifted by about 1 pH unit in the acidic direction to pH 5.5. Between 35 and 50°C, the activity of the immobilized form depends on the temperature to a smaller extent than that of the soluble form. Above 50°C, the activity of immobilized glucose oxidase shows a sharper heat dependence. The enzyme-substrate interaction was not profoundly altered by the immobilization of the enzyme. The heat resistance of the immobilized enzyme was enhanced. The immobilized glucose oxidase is most stable at pH 5.5. The practical use of the immobilized glucose oxidase was tested in preliminary experiments for determination of the glucose concentration in blood sera.     

铁氰化铈薄膜固载血红蛋白修饰的过氧化氢生物传感器的制备及性能

采用电化学沉积法将铁氰化铈(CeHCF)薄膜修饰于玻碳电极(GCE)表面,得到铁氰化铈薄膜修饰玻碳电极;将血红蛋白(Hb)固载于该修饰电极表面,成功制得了Hb/CeHCF/GCE过氧化氢生物传感器.考察了铁氰化铈薄膜修饰玻碳电极的氧化还原机理和制备条件,并对血红蛋白在电极上的电子传递过程进行了较为深入的研究.结果表明,铁氰化铈薄膜为血红蛋白提供了温和的固载环境,可实现血红蛋白与电极表面的直接电子转移,提高了血红蛋白的电化学活性;所制得的传感器对过氧化氢具有较高的催化响应和较强的稳定性.相关研究结果在生物医学和临床医学领域具有一定的借鉴意义.     

Denitrification and removal of heavy metals from waste water by immobilized microorganisms

Pseudomonas fluorescens, immobilized on soft polyvinyl chloride granules containing up to 35% softeners as carbon source, was used for simultaneous removal of nitrate and heavy metals. In typical continuous column operation, a 100 mg/L nitrate input solution was reduced to a 20 mg/L output at a feeding rate of 1500 mL/h, with a capacity of 14 kg/day/m³, and with an efficiency of 79%. In the same column, Pb(NO₃)₂ concentration was reduced from 1.0 to 0.05−0.1 mg/L and ZnSO₄ concentration was reduced from 10 to 5 mg/L.Pseudomonas aeruginosa immobilized on an O₂ plasma-treated melt blown polypropylene web was used for removing 95% of a 1.7 nCi PuCl₄ activity from a nuclear plant waste water in a batch operation.     

On-chip microfluidic buffer swap of biological samples in-line with downstream dielectrophoresis

Microfluidic cell enrichment by dielectrophoresis, based on biophysical and electrophysiology phenotypes, requires that cells be resuspended from their physiological media into a lower conductivity buffer for enhancing force fields and enabling the dielectric contrast needed for separation. To ensure that sensitive cells are not subject to centrifugation for resuspension and spend minimal time outside of their culture media, we present an on-chip microfluidic strategy for swapping cells into media tailored for dielectrophoresis. This strategy transfers cells from physiological media into a 100-fold lower conductivity media by using tangential flows of low media conductivity at 200-fold higher flow rate versus sample flow to promote ion diffusion over the length of a straight channel architecture that maintains laminarity of the flow-focused sample and minimizes cell dispersion across streamlines. Serpentine channels are used downstream from the flow-focusing region to modulate hydrodynamic resistance of the central sample outlet versus flanking outlets that remove excess buffer, so that cell streamlines are collected in the exchanged buffer with minimal dilution in cell numbers and at flow rates that support dielectrophoresis. We envision integration of this on-chip sample preparation platform prior to or post-dielectrophoresis, in-line with on-chip monitoring of the outlet sample for metrics of media conductivity, cell velocity, cell viability, cell position, and collected cell numbers, so that the cell flow rate and streamlines can be tailored for enabling dielectrophoretic separations from heterogeneous samples.     

Preparation of glass capillary columns

Summary Glass capillary column chromatography is the most rapidly growing part of gas chromatography. There are many complex new analytical tasks and they require special capillary columns. Fortunately there is a wide range of column preparation methods available, and they make the preparation of glass capillary columns a more varied job than that of packed columns. In this paper these methods are reviewed and suggestions are given for making task-oriented columns.     

Determination of phenol and catechol concentrations with oxygen probes coated with immobilized enzymes or immobilized cells

The enzyme phenol 2-hydroxylase was immobilized on Sepharose and used in conjunction with an O₂ electrode for quantitating phenol. Similarly, catechol 1,2-oxygenase was used for quantitating catechol. A third probe was prepared by immobilization ofTrichosporon cutaneum cells rather than purified phenol 2-hydroxylase for phenol quantitation. The whole cell system gave results comparable to the immobilized enzyme system.     

Continuous production of butanol with immobilized cells ofClostridium acetobutylicum

Spores ofClostridium acetobutylicum were immobilized in calcium alginate. An active gel preparation was obtained after outgrowth of the spores to vegetative cells within the gel matrix. A 100 mL column containing the immobilized cells was used for continuous production. At steady-state conditions the productivity of butanol was 67 g/L reactor volume/day.     

Preparation and loading buffer study of polyvinyl alcohol‐based immobilized Ti4+ affinity chromatography for phosphopeptide enrichment

Despite recent advances in phosphoproteomics, an efficient and simple enrichment protocol is still a challenge and of high demand aiming at large‐scale plant phosphoproteomics studies. Here, we developed a novel loading buffer system for synthesized immobilized metal affinity chromatography material targeting plant samples, which was prepared by a simple one‐step esterification between polyvinyl alcohol and phosphoric acid and then was subjected to immobilize Ti⁴⁺. SEM and Fourier transform IR spectroscopy were used to assure the synthesis protocol of the polyvinyl alcohol‐based Ti⁴⁺ immobilized material, and the specific surface areas and pore volumes of the polymers were measured. The selectivity for phosphopeptide enrichment from α‐casein was improved by optimizing the pH and components of the loading buffer. By using potassium hydrogen phthalate/hydrochloric acid with pH at 2.50 as the loading buffer, 19 phosphopeptides with high intensity were identified. The final optimized protocol was adapted to salt‐stressed maize leaves for phosphoproteome analysis. A total of 57 phosphopeptides containing 59 phosphorylated sites from 50 phosphoproteins were identified in salt‐stressed maize leaf. The research was meaningful to obtain much more information about phosphoproteins leading to the comprehension of salt resistance and salt‐inducible phosphorylated processes of maize leaves.     

Capillary columns with immobilized stationary phases. Part 4: A moderately polar phase,OV-1701

Whereas the immobilization of apolar silicone phases is essentially understood and mastered, the corresponding treatment of even moderately polar phases remains problematical. Upon attack by peroxide radicals, these phases respond by forming active transformation products rather than by bonding to the support surface or to neighboring molecules. OV-1701 is at present the most polar stationary phase which can reasonably be immobilized. An essential feature of the practical procedure is the prevention of film breakage after coating the inert support surface and before immobilization. Two ways of overcoming this problem are presented.