待定模板印迹聚合物对高丰度鸡蛋清蛋白质的脱除

将鸡蛋清溶液作为“待定模板”制备分子印迹聚合物,得到的聚合物作为色谱固定相,显示出能脱除高丰度蛋白质的能力。采用不同浓度的鸡蛋清进行印迹,可以得到具有不同蛋白脱除性质的聚合物。经过实验室自制的注射器色谱系统处理,蛋清中的高丰度蛋白质(如鸡卵清蛋白、溶菌酶、转铁蛋白)可从相应样品溶液当中去除。随着这些高丰度蛋白质谱峰消失,其它组分的质谱信号变得更加明显。根据文献结果及实验所得质谱数据,判定这些蛋白质分别是卵清白蛋白关联蛋白、转铁蛋白关联蛋白质、卵粘蛋白及黄素蛋白。实验表明,待定模板印迹方法具有脱除高丰度蛋白质,并同时保留、富集低丰度修饰蛋白质的能力。     

Normalization strategies for river bed sediments: A graphical approach

The assessment of the degree of contamination of river bed sediments is a complex task, whose main difficulty arises from the application of correct normalization methods. A proper selection of background values and reference elements must be carried out to ensure a correct examination of the sediments. According to the results of our study, normalization by considering in-depth values lead to the most satisfactory results, when the background concentrations were inferred from the 25% lower hinge of box-plots graphs. This percentile was considered to be a conservative approach, which did not lead to overestimation of the actual contamination status of the sediments. Also, local background ranges were obtained by means of the calculation: median ± 2 median absolute deviation (MAD). Double-normalizations, as those made for the calculation of the Enrichment Factor, which use a reference element and a background value were considered more useful than single-normalizations against a reference element. Finally, the Enrichment Factors (EF) calculated on the basis of box-plot derived backgrounds were compared with those obtained by using average crustal and shale values, and local surface pristine values. The EFs obtained for the bulk fraction (< 2 mm) using crustal values were comparable to those obtained using local backgrounds, whereas shale values were more adequate for the fine fraction (< 63 µm). Pristine local values lead to an overestimation of the enrichment factors for most of the elements.     

Energetic analysis of fragment docking and application to structure-based pharmacophore hypothesis generation

We have developed a method that uses energetic analysis of structure-based fragment docking to elucidate key features for molecular recognition. This hybrid ligand- and structure-based methodology uses an atomic breakdown of the energy terms from the Glide XP scoring function to locate key pharmacophoric features from the docked fragments. First, we show that Glide accurately docks fragments, producing a root mean squared deviation (RMSD) of <1.0 Å for the top scoring pose to the native crystal structure. We then describe fragment-specific docking settings developed to generate poses that explore every pocket of a binding site while maintaining the docking accuracy of the top scoring pose. Next, we describe how the energy terms from the Glide XP scoring function are mapped onto pharmacophore sites from the docked fragments in order to rank their importance for binding. Using this energetic analysis we show that the most energetically favorable pharmacophore sites are consistent with features from known tight binding compounds. Finally, we describe a method to use the energetically selected sites from fragment docking to develop a pharmacophore hypothesis that can be used in virtual database screening to retrieve diverse compounds. We find that this method produces viable hypotheses that are consistent with known active compounds. In addition to retrieving diverse compounds that are not biased by the co-crystallized ligand, the method is able to recover known active compounds from a database screen, with an average enrichment of 8.1 in the top 1% of the database.     

聚酰胺柱填料对水中有机物的吸附与分离研究——Ⅰ.水溶性染料的富集与分离

作者研制成一种新型聚酰胺类柱填料,具有可控的粒度范围和机械性能,对水溶性染料有很大的吸附容量和选择性,可用于微量染料的分离制备与分析。     

Applications of multifunctional magnetic nanoparticles for the enrichment of proteins for PAGE separation

This paper describes the applications of multifunctional magnetic nanoparticles (MNPs) for the enrichment of low‐abundance proteins for polyacrylamide gel electrophoresis (PAGE) separation. The hemoglobin‐functionalized MNPs, named Hb–MNPs, were obtained based on electrostatic interactions and covalent binding between the hemoglobin (Hb) and the MNPs. It was demonstrated that the proteins in human serum were selectively conjugated to Hb‐MNPs, which can be used for the selective enrichment of low‐abundance proteins. Three and seven kinds of proteins were identified by MS after 1‐D and 2‐D PAGE, respectively. Comparing with native PAGE without the treatment of MNPs, some proteins were observed, such as human serum amyloid P component (SAP), vitamin D‐binding protein, and serine peptidase inhibitor. Because the high concentration of SAP can be considered as a signal for the neurodegeneration of Alzheimer's disease, the present Hb‐MNPs‐based method was applied to investigate the serum level of SAP for the diagnosis of Alzheimer's disease, and the results are satisfying.     

Selective enrichment of aminothiols using polysorbate 20-capped gold nanoparticles followed by capillary electrophoresis with laser-induced fluorescence

In this article, we report a simple method for selective enrichment of aminothiols using Tween 20-capped gold nanoparticles (AuNPs) prior to capillary electrophoresis coupled with laser-induced fluorescence (CE-LIF). Compared to citrate-capped AuNPs, Tween 20-capped AuNPs exhibit the ability to disperse in a highly saline solution and selectively extract aminothiols through the formation of Au–S bonds. After extraction and centrifugation, 1 mM thioglycollic acid (TGA) was utilized to remove aminothiols that attached to the NP surfaces. After a solution of 8.0 mL aminothiols were extracted using 2× AuNPs (200 μL), the extracted aminothiols derivatized with o-phthalaldehyde at pH 12.0 were detected by CE-LIF. As a result, the limits of detection at a signal-to-noise ratio of 3 for homocysteine (HCys), glutathione (GSH), and γ-glutamycysteine (Glu-cys) are 4013.2, 79.8, and 382.8 pM, respectively. The use of this probe provided approximately 11-, 282-, and 21-fold sensitivity improvements for HCys, GSH, and Glu-cys, respectively. A practical analysis of HCys, GSH, and Glu-cys in human urine sample has been accomplished by this present method.     

Development of an epoxy-based monolith used for the affinity capturing of Eschericha coli bacteria

An epoxy-based monolith has been developed for use as hydrophilic support in bioseparation. This monolith is produced by self-polymerization of polyglycerol-3-glycidyl ether in organic solvents as porogens at room temperature within 1 h. One receives a highly cross-linked structure that provides useful mechanical properties. The porosity and pore diameter can be controlled by varying the composition of the porogen. In this work, an epoxy-based monolith with a high porosity (79%) and large pore size (22 μm) is prepared and used in affinity capturing of bacterial cells. These features allow the passage of bacterial cells through the column. As affinity ligand polymyxin B is used, which allows the binding of gram-negative bacteria. The efficiency of the monolithic affinity column is studied with Escherichia coli spiked in water. Bacterial cells are concentrated on the column at pH 4 and eluted with a recovery of 97 ± 3% in 200 μL by changing the pH value without impairing viability of bacteria. The dynamic capacity for the monolithic column is nearly independent of the flow rate (4 × 10⁹ cells/column). Thereby, it is possible to separate and enrich gram-negative bacterial cells, such as E. coli, with high flow rates (10 mL/min) and low back pressure (<1 bar) in a volume as low as 200 μL compatible for real-time polymerase chain reaction, microarray formats, and biosensors.     

Green analytical chemistry in sample preparation for determination of trace organic pollutants

The principles of green chemistry are applied to not only chemical engineering and synthesis, but also increasingly analytical chemistry. We describe environment-friendly analytical techniques applied to isolate and to enrich trace organic pollutants from solid and aqueous samples. Amounts of organic solvents used in analytical laboratories are reduced by applying solventless extraction, extraction using other types of solvent, assisted solvent extraction and miniaturized analytical systems.     

Cross-flow microfiltration system for rapid enrichment of bacteria in water

Permanent monitoring of waterborne pathogens is important for securing the hygiene of water. Enumerating bacteria in water at low concentrations and minute quantities demands rapid and efficient enrichment methods in order to improve the signal-to-noise ratio of subsequent determination methods. In this work an automated cross-flow microfiltration (CFM) system is presented which is usable in the field to concentrate large volumes of environmental water for analytical purposes. It was designed as a rapid enrichment apparatus achieving high recovery and high concentration factors. The efficiency of the CFM system was studied for E. coli spiked in a 10-L tap water sample. By this technique, a 10-L water sample was concentrated by a factor of 200 in 15 min. The high and consistent recovery of 91.3 ± 5.4% living cells in the concentration range 0.01 and 100 cfu mL⁻¹ is suitable for rapid enumeration of bacteria in water.     

C18键合硅胶柱富集/AAS法测定水体中痕量锰的研究

对水体中痕量锰的C18键合硅胶富集／AAS法进行了研究。重点讨论了该法测定的一些影响因素及最佳条件。结果表明,常温下对于10^-6mol／L浓度的锰,pH5．50～6．50范围内,螯合剂用量在0．20～0．40mL范围内时,测定结果最佳;且酒石酸、HA、柠檬酸、葡萄糖的质量浓度达1．00mg／L时对测定无影响。该法测定水中锰离子的浓度,检出限为0．03umol／L(3σ),在0．50～5．00umol／L范围内,具有很好的线性关系。