Directed development of high-performance membranes via high-throughput and combinatorial strategies

Combinatorial strategies are for the first time applied in membrane technology and prove to be a powerful new tool in the search for novel membrane materials. The selected system for this study is a polyimide solvent-resistant nanofiltration membrane prepared via phase inversion. The phase inversion process is a typical membrane synthesis procedure involving a large number of compositional components, which can each be varied in a wide concentration range. The optimization of the membrane dope composition was performed using evolutionary optimization via genetic algorithms. Compared with the best commercially available membranes, a substantially improved membrane performance could be realized, both on the level of membrane selectivity and on that of permeability. The miniaturized high-throughput synthesis procedure could be scaled up successfully when the polymer dope was sufficiently viscous. It can be anticipated that application of combinatorial techniques can potentially lead to major improvements in all fields of membrane technology, for example water treatment, gas separation, and dialysis, not only on the compositional level but also for instance on the level of membrane synthesis posttreatment and operational conditions.     

Method development for HILIC assays

In this review, method development for hydrophilic interaction LC (HILIC) is highlighted. HILIC is a chromatographic technique that uses aqueous-organic solvent mobile phases with a high organic-solvent fraction, and a hydrophilic stationary phase. It is mainly applied for the separation of polar and hydrophilic compounds. Method development, in general, can be done uni- or multivariately. In the univariate approach, the factors that are expected to potentially affect the separation of the compounds will be examined sequentially and one-at-a-time. All HILIC methods found in the literature were developed in this way. For these methods, the analytes, the considered factors, the selected responses, and the finally chosen experimental conditions are discussed in this review. Where examined, the method validation and the comparison with other analytical assay methods is also described. For the multivariate method-development approach, which is based on the use of experimental designs, only a possible strategy is presented, because of the lack of relevant publications in the literature.     

多肽新药研发策略研究进展

多肽药物具有生物活性高、药用剂量小、产业化开发优势明显等诸多优点,已成为全球关注的创新药物研发热点之一.但是其代谢不稳定、半衰期短及较难通透组织屏障等缺点严重阻碍了多肽新药在临床治疗中的广泛应用.为了解决这些限制多肽药物的瓶颈,本课题组发展了一系列的改造策略.通过这些策略的应用,以期加快多肽药物临床应用的步伐.本文主要结合本课题组的工作对多肽新药创制过程中所遇到的关键问题及解决思路进行综述.     

European Union strategies for the protection of the environment and sustainable development

Currently there are three main parallel processes aiming either to improve the environment or to achieve sustainable development within the European Union (EU): the 6th Environmental Action Programme (6th EAP), the Cardiff Process and the Strategy for Sustainable Development (SDS). The 6th EAP provides key environmental objectives and the framework to set other environmental strategies. The Cardiff Process plays a fundamental role in the progression of environmental integration, as an essential tool to implement the EAP and to achieve sustainable development. Sustainable development is a major political mandate for the EU and the SDS aims to provide long-term objectives and measures to promote and implement it. The EU Chemicals policy is an example of a European policy extracting and using some new approaches and principles characterising the political processes described above. The aim of this paper is to analyse these political processes, their reciprocal interactions, highlight their innovative approaches, as well as providing concrete example of sectoral policy implementing them.     

Method development approaches for capillary ion electrophoresis

Capillary ion electrophoresis (CIE) is a capillary electrophoretic technique optimized for rapid determination of low-molecular-mass inorganic and organic ions. CIE predominantly employs indirect UV detection since the majority of the analytes lack specific chromophores. Described are three methods for detection and electrolyte optimization. The first method discussed approaches for optimizing sensitivity, selectivity and peak confirmation using a chromate electrolyte and selected detection wavelengths. Peak confirmation is aided by using both direct detection of analytes. The second and third methods involve an unattended electrolyte development approach for instruments that only provide fresh electrolyte on the injection side of the capillary. The electrolyte composition is changed in both the injection side vial and in capillary before each sample injection while leaving the receiving side electrolyte vial constant at the initial electrolyte composition. In one mode, the concentration of the electroosmotic flow (EOF) modifier used to induce anodic flow is varied while keeping the background electrolyte composition constant. In a second experiment, the background electrolyte co-ion is sequentially changed from high mobility to low mobility while keeping the EOF modifier concentration constant. The end effect is to achieve a broad range of controlled peak symmetry for analytes in a simple matrix. The results are compared to separations obtained when the injection side and receiving side electrolytes are manually matched.     

Method development for proteome stabilization in human saliva

Human saliva is a biological fluid with emerging early detection and diagnostic potentials. However, the salivary proteome suffers from rapid degradation and thus compromises its translational and clinical utilities. Therefore, easy, reliable and practical methods are urgently required for the storage of human saliva samples. In this study, saliva samples from healthy subjects were collected and stored at room temperature (RT) and 4 °C for different lengths of time with and without specific protein stabilization treatments. SDS-PAGE was run to compare the protein profiling between samples. Reference proteins, β-actin and interleukin-1 β (IL1β), were chosen to evaluate salivary protein stability. Immunoassay was used for the detection of these target proteins. All data was compared with the positive control that had been kept at −80 °C. The results show that the salivary proteome that has been stored at 4 °C with added protease inhibitors was stable for approximately two weeks without significant degradation. By adding ethanol to the samples, the salivary proteome was stabilized at RT. After optimization, a simple, robust and convenient method is developed for the stabilization of proteins in human saliva that does not affect the downstream translational and clinical applications. The salivary proteome could be stabilized without significant degradation by adding ethanol at RT for about two weeks. This optimized method could greatly accelerate the clinical usage of saliva for future diagnosis.     

Computerized design of separation strategies by reversed-phase liquid chromatography: development of DryLab software

The development of DryLab software is a special achievement in analytical HPLC which took place in the last 16 years. This paper tries to collect some of the historical mile stones and concepts. DryLab, being always subject to change according to the needs of the user, never stopped being developed. Under the influence of an ever changing science market, the DryLab development team had to consider not just scientific improvements, but also new technological achievements, such as the introduction of Windows 1.0 and 3.1, and later Windows NT and 2000. The recent availability of new 32-bit programming tools allowed calculations of chromatograms to be completed more quickly so as to show peak movements which result for example from slight changes in eluent pH. DryLab is a great success of interdisciplinary and intercontinental cooperation by many scientists.     

胰岛素反相制备色谱的方法开发

以胰岛素反相制备色谱方法的开发和优化为目标,通过考察色谱保留参数、峰展宽及样品流出曲线的浓度分布等色谱参数,对流动相梯度、色谱填料、载样量等色谱条件进行了优化,并建立了胰岛素制备色谱峰参数的描述方法。结果表明,所建立的方法可快速筛选出最适于胰岛素分离的色谱条件(包括流动相梯度及分离填料),即流动相中的强洗脱溶剂(有机相)需采取缓梯度窄区间的变化条件,筛选出的分离填料需具备峰向两侧展宽且展宽程度较小、样品最高浓度居中分布的特点。将方法用于实际胰岛素粗品的纯化制备,获得了杂质去除效果好、胰岛素纯度高的产品。该法为胰岛素反相色谱纯化制备方法的快速建立提供了指导,具有较强的实用价值,同时为发展大分子化合物的制备色谱方法提供了参考。     

Method development by an expert system advantages and limitations

Several approaches can be used for the prediction of the optimum eluent composition in RP-HPLC, but only a few are known that use the structure of the solute. The latest release of the computer program EluEx, version 3.0, was developed to help the chromatographer in practical work. The program is based on the prediction of the pK_a and log P (logarithm of 1-octanol-water partition coefficient) values of the solutes. The first eluent suggestion can be done without any preliminary practical work, based on the structural formulae of the solutes. In our experience, two or three experiments are usually sufficient to determine the optimized binary conditions. The surface heterogeneity and the diversity of RP columns, such as the effect of silanol interaction, can be handled by the program only to a limited extent. If the difference in hydrophobicity between two compounds is small, the elution order cannot be predicted properly in all instances. The same is true for some isomers, e.g., diastereomers. In this paper, the results of applying the program to some neutral, acidic and basic solutes are summarized.     

Exploring new synthetic strategies in the development of a chemically activated Ru-based olefin metathesis catalyst

The objective of this work was to develop an industrially relevant olefin metathesis initiator, which circumvents the expensive, patent protected, often cumbersome preparative routes via Grubbs benzylidene complexes. Upon coordination of a Schiff base ligand to a second-generation ruthenium allenylidene complex, the formation of three catalyst isomers was observed. The major isomer was successfully isolated, and tested in a few olefin metathesis reactions. Acids such as HCl and HSiCl(3) were found to boost the metathesis reaction but the in situ formation of a neutral Ru carbyne complex restricted the catalytic capacity. Using the Lewis acid PhSiCl(3), the formation of a carbyne species was avoided, and turnover numbers up to 30,000 were reached in the ring-opening metathesis polymerisation of cycloocta-1,5-diene.     

Evaluation of experimental strategies for the development of chiral chromatographic methods based on diastereomer formation

The past two decades has seen explosive growth in the field of chirality as illustrated by the rapid progress in the various facets of this intriguing field. Firstly, it is the basic understanding of the importance of chirality and, secondly, the awareness of the therapeutic pitfalls due to failure to recognize chirality that have paved the way for a rejuvenated interest in the field. Needless to say that the impetus for chiral separation advancement and enhancement has been found to be the highest in the past decade and still continues to be an area of high focus. In this regard, both direct and indirect separation approaches have been instrumental in placing into literature stereoselective pharmacokinetic and pharmacodynamic data of plethora of drug racemates. Also, today, the cloud of uncertainty associated with the development of a chiral molecule is a thing of the past because the field is so evolved and numerous options are available for stereoselective analysis. However, the decision to advance either a single enantiomer or a racemate for development has to be made by a rational approach with adequate justification. Although indirect method of chiral separation has been well established with numerous examples of well-documented cases of stereoselective pharmacokinetic data, there is a growing need for a review that provides a strategic overview of considerations and key issues for developing chromatographic methods based on diastereomer formation. This review provides a general framework for the exploratory planning and a definitive game plan for the establishment of chiral methods based on diastereomer formation. Also, it provides an exhaustive list of applications of numerous chiral derivatization reagents that have been used in the generation of stereoselective pharmacokinetic data.     

Method development for the separation of steroids by capillary electrochromatography

A rapid capillary electrochromatography (CEC) method was developed to separate five structurally related steroid compounds from the production line of steroid hormones. The separation was performed on a Hypersil C8 MOS and Unimicro C18 stationary phases using acetonitrile (ACN), methanol (MeOH), and tetrahydrofuran (THF) as organic modifiers and tris(hydroxymethyl)aminomethane (Tris) as buffer additive. The Hypersil C8 MOS stationary phase performed best together with ACN as organic modifier and Tris buffer. The method was extensively tested for ruggedness with respect to sensitivity to temperature, ACN composition, pH change, concentration of Tris buffer, injected plug length, and run‐to‐run and day‐to‐day repeatability. The minimal detectable concentration and amount were investigated for quantification purposes. The developed CEC method was shown to be fast, rugged, and well suited for quantification of the steroids under study.     

Method development for the high-performance liquid chromatographic enantioseparation of 2-cyanocycloalkanols

An indirect high-performance liquid chromatographic method is developed for the enantioseparation of cis- and trans-2-cyanocyclopentanol and -cyclohexanol. The racemic cis-(1S,2S and 1R,2R)- or trans-(1S,2R and 1R,2S)-2-cyanocycloalkanols are converted to their diastereomers formed with (S)-(+)- or (R)-(-)-alpha-methoxy-alpha-(trifluoromethyl)phenylacetyl chloride. The diastereomers are separated on a reversed-phase column, and the conditions of derivatization and HPLC analysis are optimized.     

吸附固定相开管毛细管电色谱方法的建立（英文）

 首次将管壁吸附作用作为开管毛细管电色谱固定相制备的推动力,成功地建立了称为“吸附固定相开管毛细管电色谱”的一种新方法。原理是：选择合适的条件,让荷正电的化合物在毛细管管壁上充分吸附,直接用吸附层作为固定相。目前,已有数类化合物被用作固定相物质,其中包括阳离子表面活性剂如十六烷基三甲基溴化铵（CTAB）、碱性蛋白质如溶菌酶和细胞色素C、碱性小肽如赖氨酸-酪氨酸和赖氨酸-丝氨酸-酪氨酸、以及碱性氨基酸如L-赖氨酸。CTAB吸附固定相用于分离电中性化合物,其它吸附固定相用于手性分离。     

Rational design of biomimetic molecularly imprinted materials: theoretical and computational strategies for guiding nanoscale structured polymer development

In principle, molecularly imprinted polymer science and technology provides a means for ready access to nano-structured polymeric materials of predetermined selectivity. The versatility of the technique has brought it to the attention of many working with the development of nanomaterials with biological or biomimetic properties for use as therapeutics or in medical devices. Nonetheless, the further evolution of the field necessitates the development of robust predictive tools capable of handling the complexity of molecular imprinting systems. The rapid growth in computer power and software over the past decade has opened new possibilities for simulating aspects of the complex molecular imprinting process. We present here a survey of the current status of the use of in silico-based approaches to aspects of molecular imprinting. Finally, we highlight areas where ongoing and future efforts should yield information critical to our understanding of the underlying mechanisms sufficient to permit the rational design of molecularly imprinted polymers.     

Method development for measuring trace levels of penicillins in aqueous environmental samples

A method based on liquid chromatography/mass spectrometry with an electrospray ion source and a single quadrupole instrument (LC/ES-MS) has been developed for determining trace levels of eight widely used penicillins in aqueous environmental samples. Analyte extraction was performed from 4 L tap water, 2 L groundwater, 1 L river water, 0.2 L treated sewage and 0.1 L raw sewage, by using a Carbograph 4 cartridge. During removal of the solvent, penicillins were purposely allowed to convert into their penicilloyl methyl esters. This 'in situ' derivatization step resulted in a dramatic enhancement of the response of the ES-MS system for non-amphoteric penicillins. Analyte recoveries were better than 80% irrespective of the type of aqueous sample, with the exception of amoxicillin (76%) and ampicillin (77%) in tap water. At the level of 50 ng/L of each analyte in ground water, the within-day precision was in the range 6-10%. Calibration curves were linear for injected amounts up to 800 ng, with R(2) in the range 0.9952-0.9995. When injecting large equivalent volumes of the aqueous samples, the electrospray matrix effect altered in-source collision-induced dissociation (CID) spectra of the analytes by severely weakening signals for fragment ions, as compared to spectra of reference standards. Remedies to obviate this anomalous unwelcome effect are suggested. On the basis of a signal-to-noise ratio of 10, limits of quantification were estimated to range between 2 (cloxacillin) and 24 ng/L (amoxicillin) in river water.     

Model films of cellulose: I. Method development and initial results

This report presents a new method for the preparation of thin cellulosefilms. NMMO (N-methylmorpholine-N-oxide) was used to dissolve cellulose andaddition of DMSO (dimethyl sulfoxide) was used to control viscosity of thecellulose solution. A thin layer of the cellulose solution is spin-coated ontoasilicon oxide wafer and the cellulose is precipitated in deionised water. Thecellulose film is anchored onto the silicon oxide wafer by a saturated polymerlayer. Among many different polymers tested, PVAm (polyvinylamine) and G-PAM(glyoxalated-polyacrylamide) worked well. The preparation of cellulose modelfilms described in this paper resulted in films with thicknesses in the range20–270 nm and the thickness can be controlled by alteringtheconcentration of cellulose solution by addition of different amounts of DMSO.The films were cleaned in deionised water and were found to be free fromsolvents by ESCA analysis and contact angle measurements. The molecular weightdistribution of the cellulose surface material shows that there is only minorbreakdown of the cellulose chains, mainly by cleavage of the longest molecularmass fraction and without creation of low molecular mass oligomers of glucose.