A novel one-pot strategy to prepare ß-cyclodextrin functionalized capillary monoliths for enantioseparation of basic drugs.

With native ß-cyclodextrin (ß-CD) added into the polymerization mixture directly, a novel, convenient and low-cost one-pot strategy was developed to prepare the ß-CD functionalized organic polymer monolithic capillary column. Diazabicyclo[5.4.0]undec-7-ene (DBU) as a basic catalyst for the ring opening reaction between ß-CD and glycidyl methacrylate (GMA) was introduced into the polymerization system for the first time. Thereby, two consecutive reactions namely the in situ methacrylation of ß-CD and copolymerization reaction can be achieved in one pot. The preparation conditions including the type and composition of porogens，the ratio of functional monomer to crosslinker and amount of 2-acrylamido-2-methyl propane sulfonic acid (AMPS) were optimized. The specific surface area and morphology of the prepared monolith were characterized using scanning electron microscopy (SEM) and nitrogen adsorption analysis, respectively. Raman spectroscopy and nuclear magnetic resonance (NMR) spectroscopy confirmed that ß-CD was covalently bonded onto the monolith successfully. Then, the monolithic column was applied to enantioseparation of six basic drugs in capillary electrochromatography (CEC). Under the optimal conditions, tropicamide, homatropine, homatropine methylbromide, brompheniramine, chlorpheniramine and clorprenaline were all totally separated with the resolution (Rs) values of 2.84, 4.70, 4.61, 3.01, 2.57 and 2.33, respectively. Furthermore, the column demonstrated satisfactory stability and repeatability of retention time and enantioselectivity using homatropine as model analyte.

The use of urinary proteomics in the assessment of suitability of mouse models for ageing.

Ageing is a complex process characterised by a systemic and progressive deterioration of biological functions. As ageing is associated with an increased prevalence of age-related chronic disorders, understanding its underlying molecular mechanisms can pave the way for therapeutic interventions and managing complications. Animal models such as mice are commonly used in ageing research as they have a shorter lifespan in comparison to humans and are also genetically close to humans. To assess the translatability of mouse ageing to human ageing, the urinary proteome in 89 wild-type (C57BL/6) mice aged between 8-96 weeks was investigated using capillary electrophoresis coupled to mass spectrometry (CE-MS). Using age as a continuous variable, 295 peptides significantly correlated with age in mice were identified. To investigate the relevance of using mouse models in human ageing studies, a comparison was performed with a previous correlation analysis using 1227 healthy subjects. In mice and humans, a decrease in urinary excretion of fibrillar collagens and an increase of uromodulin fragments was observed with advanced age. Of the 295 peptides correlating with age, 49 had a strong homology to the respective human age-related peptides. These ortholog peptides including several collagen (N = 44) and uromodulin (N = 5) fragments were used to generate an ageing classifier that was able to discriminate the age among both wild-type mice and healthy subjects. Additionally, the ageing classifier depicted that telomerase knock-out mice were older than their chronological age. Hence, with a focus on ortholog urinary peptides mouse ageing can be translated to human ageing.

Preparation and characterization of a polystyrene/bovine serum albumin nanoparticle-coated capillary for chiral separation using open-tubular capillary electrochromatography.

Polystyrene (PS) nanoparticles coated by BSA, hereafter denoted as PS/BSA, were prepared and chemically immobilized for the first time onto a capillary inner wall for open-tubular CEC (OTCEC). EOF and scanning electron micrography were used to characterize the prepared nanoparticle-coated capillaries. To investigate the performance of the prepared columns in OTCEC, chiral separation of d,l-tryptophan (dl-Trp) was performed in monolayer BSA-modified capillary and PS/BSA nanoparticle-coated columns. The results indicated that the nanoparticle-modified column afforded a higher resolution compared with the monolayer type. Rapid enantioseparation of dl-Trp (within 3 min) was achieved with the PS/BSA-immobilized column using an electroosmotic pump-assisted CEC. Enantiomer separations of other compounds like dl-tyrosine and warfarin were also achieved with the column. Besides, run-to-run and column-to-column repeatabilities of the PS/BSA-coated column in the chiral separation were systematically introduced.

Facile preparation of polysaccharide-coated capillaries using a room temperature ionic liquid for chiral separations.

In this study, the dissolution of polysaccharides into an ionic liquid was investigated and applied as a coating onto the capillary walls of a fused-silica capillary in open-tubular CEC. The coating was evaluated by examining the chiral separation of two analytes (thiopental, sotalol) with three cellulose derivatives (cellulose acetate, cellulose acetate phthalate, and cellulose acetate butyrate). Baseline separation of thiopental enantiomers was achieved by use of each polysaccharide coating (Rs: 7.0, 8.1, 7.1), while sotalol provided partial resolution (Rs: 0.7, 1.0, 0.9). In addition, reproducibility of the cellulose-coated capillaries was evaluated by estimating the run-to-run and capillary-to-capillary RSD values of the EOF. Both stability and reproducibility were very good with RSD values of less than 7%.

Electrochromatography on acrylate-based monolith in cyclic olefin copolymer microchip: a cost-effective and easy-to-use technology.

This article shows that there is great interest in using an electrochromatographic microchip made of hexyl acrylate (HA) based porous monolith cast within the channel of a cyclic olefin copolymer (COC) device. The monolith is simultaneously in situ synthesized and anchored to the inner walls of the channel in less than 10 min. By appropriate choice of light intensity used during the synthesis, the separation efficiency obtained for nonpolar solutes such as polycyclic aromatic hydrocarbons (PAH) is increased up to 250 000 plates/m. The performance of this HA-filled COC microchip was investigated for a wide range of analytes of varying nature. The reversed-phase separation of four aflatoxins is obtained in less than 2 min. The baseline separation of a mixture of neurotransmitters including six amino acids and two catecholamines is possible thanks to the superimposition of the differences in electrophoretic mobility on the chromatographic process. The durability of the system at pH 13 allows the separation of five biogenic amines and the quantitative determination of two of them in numerous wine samples. The feasibility of on-line preconcentration is also demonstrated. Hydrophilic surface modification of COC channel via UV-photografting with poly(ethylene glycol) methacrylate (PEGMA) before in situ synthesis of HA, is necessary to reduce the adsorption of very hydrophobic solutes such as PAH during enrichment. The detection limit of fluoranthene is decreased down to less than 1 ppb with a preconcentration of 4.5 h on the HA-filled PEGMA functionalized COC microchip.

Integrative analyses for omics data: a Bayesian mixture model to assess the concordance of ChIP-chip and ChIP-seq measurements.

The analysis of different variations in genomics, transcriptomics, epigenomics, and proteomics has increased considerably in recent years. This is especially due to the success of microarray and, more recently, sequencing technology. Apart from understanding mechanisms of disease pathogenesis on a molecular basis, for example in cancer research, the challenge of analyzing such different data types in an integrated way has become increasingly important also for the validation of new sequencing technologies with maximum resolution. For this purpose, a methodological framework for their comparison with microarray techniques in the context of smallest sample sizes, which result from the high costs of experiments, is proposed in this contribution. Based on an adaptation of the externally centered correlation coefficient ( Schäfer et al. 2009 ), it is demonstrated how a Bayesian mixture model can be applied to compare and classify measurements of histone acetylation that stem from chromatin immunoprecipitation combined with either microarray (ChIP-chip) or sequencing techniques (ChIP-seq) for the identification of DNA fragments. Here, the murine hematopoietic cell line 32D, which was transduced with the oncogene BCR-ABL, the hallmark of chronic myeloid leukemia, was characterized. Cells were compared to mock-transduced cells as control. Activation or inhibition of other genes by histone modifications induced by the oncogene is considered critical in such a context for the understanding of the disease.

Microfluidic "thin chips" for chemical separations.

This paper describes the design, development and application of microfluidic "thin chips" fabricated from PDMS. Thin chips consist of multiple layers of PDMS chemically bonded onto each other. Unlike thicker PDMS chips that suffer from lack of sensitivity due to PDMS absorption in the VIS and UV range, the thinness of these chips allows for the detection of chromophoric species within the microchannel via an external fiber optics detection system. C18-modified reversed-phase silica particles are packed into the microchannel using a temporary taper created by a magnetic valve and separations using both pressure- and electrochromatographic-driven methods are detailed.

Enantioseparation of alpha-amino acids on an 18-crown-6-tetracarboxylic acid-bonded silica by capillary electrochromatography.

(-)-(18-Crown-6)-2,3,11,12-tetracarboxylic acid-bonded silica was used as the chiral stationary phase in capillary electrochromatography (CEC) for enantioseparation of some alpha-amino acids. Separation data in CEC were measured in mobile phases of varying pH, and composition of methanol and buffer, and compared with those in capillary liquid chromatography (CLC). In CEC better enantioseparation was generally obtained in the eluent of lower pH, higher buffer concentration and intermediate MeOH content, usually at the expense of analysis time. CEC showed generally better enantioselectivity and resolutions than CLC for the amino acids investigated.

Polydopamine-based permanent coating capillary electrochromatography for auxin determination.

A novel, simple, and economical method for the preparation of open-tubular capillary column using polydopamine coating was reported for the first time. After the capillary was filled with dopamine solution for 20h, polydopamine was formed and deposited on the inner wall of capillary as permanent coating via the oxidation of dopamine by the oxygen dissolved in the solution. Moreover, the electroosmotic flow of the coated capillaries was measured to be dependent on the repetitive coating times. The performance of the polydopamine-coated capillary electrochromatography was validated by the analysis of four auxins, indole-3-butyric acid (IBA), 2,4-dichlorophenoxyacetic acid (dCPAA), indole-3-acetic acid (IAA), and phenoxyacetic acid (PAA). The precisions (RSD, n=5) were in the range of 1.6-2.4% for migration time, 4.0-6.5% for peak area response, and 3.6-4.7% for peak height response for the four auxins at 1microgmL(-1) level. The detection limits were 0.185, 0.172, 0.177, and 0.259microg/mL for IBA, dCPAA, IAA, and PAA, respectively. The method was successfully used to the determination of IAA in the culture media of IAA-producing bacteria.