A CE‐based assay for human protein kinase CK2 activity measurement and inhibitor screening

A new assay for protein kinase CK2 activity determination based on the quantification of a phosphorylated substrate was developed. The common CK2 substrate peptide RRRDDDSDDD, conjugated with the fluorophore 5‐[(2‐aminoethyl)amino]naphthalene‐1‐sulfonic acid at the C‐terminus served as the analyte. By means of CZE using 2 mol/L acetic acid as electrolyte and UV detection at 214 nm, the non‐phosphorylated and the phosphorylated peptide variants could be resolved within 6 min from a complex assay mixture. By this means, activity of human CK2 could be monitored by a kinetic, as well as an endpoint, method. Inhibition of human recombinant CK2 holoenzyme by 6‐methyl‐1,3,8‐trihydroxyanthraquinone and 4,5,6,7‐tetrabromobenzotriazole resulted in IC₅₀ values of 1.33 and 0.27 μM, respectively, which were similar to those obtained with the standard radiometric assay. These results suggest that the CE/UV strategy described here is a straightforward assay for CK2 inhibitor testing.     

Effect of chloride on heavy metal mobility of harbour sediments

To evaluate the environmental impact of polluted sediments, several operationally defined sequential extraction procedures (SEPs) have been described. Salinity has long been recognised as an important variable determining the physicochemical behaviour of heavy metals in marine sediments. Thus, in the present paper, the modified BCR-SEP has been applied to harbour sediments in order to assess to what extent trace metal mobility (Cd, Cr, Cu, Ni, Pb and Zn) could be influenced by chloride content in sediments. For this, washed (W) and non-washed (NW) sediments were compared. The relative mobility order observed for the six trace metals studied was not seen to be influenced by the presence of chloride in the sediments, but an increase of mobility was observed for Cd and Zn (the most mobile metals) when chloride was present in the sediments. Characterisation of the sediments and of the pseudo-total metal contents by means of an aqua regia extraction was also assessed.     

溶液法制备柔性压阻式传感器的研究进展

柔性压阻式传感器具有结构简单、易于制备、检测范围广等优势, 在可穿戴电子器件领域中扮演着非常重要的角色. 在制备柔性压阻式传感器的众多方法中, 溶液法由于操作简单、反应条件温和、材料的适用性广泛、易于规模化制备等优势, 成为极具发展前景的制备工艺. 在此基础上, 如何进一步提高柔性压阻式传感器的力学与电学性能也成为研究者们更加关注的话题. 另外, 制备图案化、微型化、规模化的传感器阵列为柔性压阻式传感器的应用范围拓展了新的道路. 本综述首先介绍了柔性压阻式传感器的工作原理与性能指标, 同时讨论了其性能指标对传感器在实际应用中的影响. 随后, 简单介绍了其构成材料, 并通过梳理近年来溶液法制备柔性传感器的研究成果, 选取了几种典型的溶液法制备方法进行重点介绍, 指出其具备的优势及目前存在的问题. 最后, 对溶液法制备柔性传感器的发展方向进行总结与展望.     

Software tools for green and sustainable chemistry

In this review, we consider green chemistry metrics, related software tools, and the opportunities and challenges for their use in research laboratories. We provide an overview of state-of-the-art software designed both to aid researchers in planning and conducting chemical experiments and to assess sustainability of individual reactions and synthetic routes. The increasing digitalisation of research means that there is great opportunity for more extensive use of computational tools by synthetic chemists and for closer integration of green chemistry principles into the routine work of chemical laboratories. We discuss the scope for using software tools in the laboratory and assisting synthetic chemists in the adoption of green and sustainable chemistry approaches that are suitable for their specific purposes.     

Highly sensitive tITP‐CZE determination of l‐histidine and creatinine in human blood plasma using field‐amplified sample injection with mobility‐boost effect

2D computer simulation revealed that amino acids and weak electrolytes were cationized because of the migration of counter‐ion from a BGE zone to a sample zone, which encouraged electrokinetic injection (EKI) of these analytes (by the mobility‐boost (MB) effect). To investigate the effects of kinds and concentrations of counter‐ions on the MB effect and the analyte amount injected into the capillary, experiments, and 1D computer simulations were performed. When acetate was used as the counter‐ion, the LODs (S/N = 3) of l ‐histidine and creatinine, respectively, reached 0.10 and 0.25 nM because of the concentration effect by transient ITP (tITP). The concentrations of l ‐histidine and creatinine in human blood plasma obtained using the proposed method were agreed with those obtained using the conventional methods. The proposed method can be applied to the analysis of amino acids and weak bases that have similar pI and pK_a to l ‐histidine and creatinine.     

Estimation of acidity constants,ionic mobilities and charges of antimicrobial peptides by capillary electrophoresis

Capillary electrophoresis (CE) was employed for the determination of thermodynamic acidity constants (pK_a) and actual ionic mobilities of polycationic antimicrobial peptides (AMPs). The effective electrophoretic mobilities of AMPs were measured by CE in a series of the background electrolytes within a wide pH range (2.00–12.25), at constant ionic strength (25 mM) and ambient temperature, using polybrene coated fused silica capillaries to suppress sorption of cationic AMPs to the capillary wall. Eventually, Haarhoff–Van der Linde peak fitting function was used for the determination of correct migration times of some AMPs peaks that were distorted by electromigration dispersion. The measured effective mobilities were corrected to 25°C. Mixed acidity constants, , and actual ionic mobilities, m_i, of AMPs were determined by the nonlinear regression analysis of pH dependence of their effective mobilities. The values were recalculated to thermodynamic pK_as using the Debye–Hückel theory. Thermodynamic pK_a of imidazolium group of histidine residues was found to be in the range 3.72–4.98, pK_a of α‐NH₃⁺ group was in the range 6.14–6.93, and pK_a of ε‐NH₃⁺ group of lysine spanned the interval 7.26–9.84, depending on the particular amino acid sequence of the AMPs. Actual ionic mobilities of AMPs with positive charges from one to six elementary units achieved values (9.8 – 36.5) × 10^?9 m²V^?1s^?1.     

Optical and transport phenomena in CdO:La films prepared by sol-gel method

A series of lightly La-doped CdO thin films (1%, 5%, and 7%) have been prepared by a spin coater sol-gel technique on amorphous glass and crystalline Si substrates. Those prepared films were studied by X-ray diffraction (XRD), UV-VIS-NIR absorption spectroscopy, and dc-electrical measurements. The investigation shows that La doping grows slightly the CdO lattice parameter and decreases the intrinsic energygap from 2.1 eV to 1.7 eV. The optical properties were easily explained in the framework of classical Drude theory and thus all the corresponding parameters were determined. The electrical behaviour of the samples shows that they are degenerate semiconductors until the atomic percentage of the La dopant was 7% then the sample was converted into a non-degenerate semiconductor. Generally, it was observed that the conductivity and mobility of the carriers were decreased by increasing the La content in the CdO film samples.     

基于CH3NH3PbI3单晶的Ta2O5顶栅双极性场效应晶体管

Organic-inorganic hybrid perovskite methylammonium lead iodide (CH₃NH₃PbI₃) generally tends to show n-type semiconductor properties. In this work, a field-effect transistor (FET) device based on a CH₃NH₃PbI₃ single crystal with tantalum pentoxide (Ta₂O₅) as the top gate dielectric was fabricated. The p-type field-effect transport properties of the device were observed in the dark. The hole mobility of the device extracted from transfer characteristics in the dark was 8.7×10^-5 cm²·V^-1·s^-1, which is one order of magnitude higher than that of polycrystalline FETs with SiO₂ as the bottom gate dielectric. In addition, the effect of light illumination on the CH₃NH₃PbI₃ single-crystal FET was studied. Light illumination strongly influenced the field effect of the device because of the intense photoelectric response of the CH₃NH₃PbI₃ single crystal. Different from a CH₃NH₃PbI₃ polycrystalline FET with a bottom gate dielectric, even with the top gate dielectric shielding, light illumination of 5.00 mW·cm^-2 caused the hole current to increase by one order of magnitude compared with that in the dark (V_GS (gate-source voltage)=V_DS (drain-source voltage)=20 V) and the photoresponsivity reached 2.5 A·W^-1. The introduction of Ta₂O₅ as the top gate dielectric selectively enhanced hole transport in the single-crystal FET, indicating that in the absence of external factors, by appropriate device design, CH₃NH₃PbI₃ also has potential for use in ambipolar transistors.     

非晶高聚物对聚(ε-己内酯)在其与苯乙烯-丙烯腈共聚物相容共混物中球晶生长速率的影响

本文研究了聚(ε-己内酯)(PCL)在其与苯乙烯-丙烯腈共聚物(SAN)的相容共混物中球晶生长速率与共混组成和结晶温度的关系.发现聚己内酯的球晶生长速率随着SAN的含量增加而下降.由于PCL与SAN是相容共混物,因此在用二次成核动力学方程描述PCL球晶生长速率时,我们引进了相互作用参数X.结果由共混体系的结晶动力学方程计算到的X值与由平衡熔点下降方法计算到的X_(23)值是相同的;而PCL晶体的折叠表面自由能则随着SAN含量的增加而下降.这些结果说明非晶高聚物SAN有碍于PCL球晶的生长.     

Digital Microfluidics and Magnetic Bead-Based Intact Proteoform Elution for Quantitative Top-down Nanoproteomics of Single C. elegans Nematodes

While most nanoproteomics approaches for the analysis of low-input samples are based on bottom-up proteomics workflows, top-down approaches enabling proteoform characterization are still underrepresented. Using mammalian cell proteomes, we established a facile one-pot sample preparation protocol based on protein aggregation on magnetic beads and intact proteoform elution using 40 % formic acid. Performed on a digital microfluidics device, the workflow enabled sensitive analyses of single Caenorhabditis elegans nematodes, thereby increasing the number of proteoform identifications compared to in-tube sample preparation by 46 %. Label-free quantification of single nematodes grown under different conditions allowed to identify changes in the abundance of proteoforms not distinguishable by bottom-up proteomics. The presented workflow will facilitate proteoform-directed analysis on samples of limited availability.