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.     

Effect of irradiation for sterilization on beverage reference materials for the analysis of food additives

Accreditation and Quality Assurance - Reference materials for proficiency testing (PT) were prepared for 6 years. The target analytes were food additives, sorbic acid, benzoic acid, and...     

Calculation of affinities of peptides for proteins

Several methodologies were employed to calculate the Gibbs standard free energy of binding for a collection of protein-ligand complexes, where the ligand is a peptide and the protein is representative for various protein families. Almost 40 protein-ligand complexes were employed for a continuum approach, which considers the protein and the peptide at the atomic level, but includes solvent as a polarizable continuum. Five protein-ligand complexes were employed for an all-atom approach that relies on a combination of the double decoupling method with thermodynamic integration and molecular dynamics. These affinities were also computed by means of the linear interaction energy method. Although it generally proved rather difficult to predict the absolute free energies correctly, for some protein families the experimental ranking order was correctly reproduced by the continuum and all-atom approach. Considerable attention has also been given to correctly analyze the affinities of charged peptides, where it is required to judge the effect of one or more ions that are being decoupled in an all-atom approach to preserve electroneutrality. The various methods are further judged upon their merits.     

New method for prefractionation of plasma for proteomic analysis

The depth of proteome analysis is severely limited in complex samples with a wide dynamic range of protein abundance such as plasma. Removal of high‐abundance proteins should reveal the signal of lower abundance plasma proteins. However, smaller proteins may be part of larger protein complexes and hence the removal of proteins involved in complexes with high‐abundance proteins such as albumin may inhibit the search for disease biomarkers. Prefractionation of a sample divides it into fractions of reduced complexity, allowing improved detection of lower abundance proteins. Using a prefractionation device, which employs Gradiflow? technology, we were able to separate small volume plasma samples into multiple fractions based on the molecular weight and/or charge. The resulting samples of reduced complexity were directly compatible with 2‐DE. The use of this prefractionation machine may therefore be useful in the hunt for disease biomarkers.     

Methylation as a method for synthesis of radiopharmaceuticals for positron emission tomography

The main methods for the production of of ¹¹С-methylating agents and traditional and new perspective routes for their use in the synthesis of radiopharmaceuticals for positron emission tomography were considered.     

6个聚合物胞腔理论状态方程的分子参数比较

利用Ｚｏｌｌｅｒ提供的ＰＢＤ和ＰＩ两种聚合物系列样品的Ｐ－Ｖ－Ｔ数据，对Ｃｅｌｌ、Ｆｌｏｒｙ、ＳＳ、ＳＨＴ、ＳＨＴＦ和ＯＣＭ６个状态方程的分子参数及其随链结构变化的规律作了比较，得到了一些有益的结论。     

Production of Viscosity Improvers for PVC

Some oil-based samples having oxygen, ester, amide, acid and/or hydroxyl structure were prepared for using as lubricants in PVC extrusion. After characterization studies, all samples were tested in PVC formulation using Brabender W50 EHT Lab-Station mixer and extruder. The results were compared with that of a commercial product. From the mixer results, it can be noted that energy consumption was lowered for samples containing acid and amide structures. Surface roughness and opacity of the products were improved when the extruder screw speed was increased from 20 rpm to 60 rpm.     

New agents for alkoxycarbonylation of amines

Alkoxycarbonylated pyrazinols and pyrazinethiols were prepared. These compounds were shown to be convenient agents for alkoxycarbonylation of aliphatic amines.     

Microsampling for infrared spectroscopy — A comparison of different techniques for HPLC- and TLC-fractions

Infrared Spectroscopy can be employed for the identification of HPLC-and TLC-fractions. Different microsampling techniques with compound isolation were considered: transmittance measurements using micropellets and microcells with enriched solutions; other experiments were done with accessories for diffuse reflectance. The performance of the techniques is limited by the isolation step. The identification limits for ideal samples (about 50 ng) can be one order of magnitude lower than for Chromatographic fractions due to sample handling problems.     

Preparation of PVA membrane for immobilization of GOD for glucose biosensor

A membrane was prepared using polyvinyl alcohol (PVA) with low and high degree of polymerization (DOP), acetone, benzoic acid (BA) and was cross-linked by UV treatment. Membrane composition was optimized on the basis of swelling index. Membrane prepared with 12% low DOP and 8% high DOP of PVA, 2% BA, dissolved in buffer containing 20% acetone and cross-linked with UV treatment exhibited lower swelling index. Fourier transform infrared (FTIR) study of the membranes showed appearance of a strong band at approximately 2337 cm(-1) when UV was used for cross-linking in the presence of benzoic acid. Scanning electron microscope (SEM) study revealed that membrane cross-linked with UV treatment was smoother. Glucose oxidase (GOD)-PVA membrane was associated with the dissolved oxygen (DO) probe for biosensor reading. Glucose was detected on the basis of depletion of oxygen, when immobilized GOD oxidizes glucose to gluconolactone. A wide detection range, 0.9-225 mg/dl was estimated from the linear range of calibration plot of biosensor reading. Membranes were reused for 32 reactions without significant loss of activity and stored for 30 days (approximately 90% activity) at 4 degrees C. Membranes were also used with real blood samples.     

Zinc Oxide Based Coatings for the UV-Protection of Wood for Outdoor Applications

Summary: Nano-sized zinc oxide (ZnO) was chosen as a suitable candidate for the UV-protection of coatings. ZnO-based acrylate coatings were applied to polycarbonate plates, glass plates and impregnated wood. Coated samples were artificially weathered (Xenon test) for at least 1500 hours and studied with regards to their optical and mechanical properties, such as color shifts (yellowing), as well as to changes in brightness, transparency or hydrophobicity. The prepared wood coatings showed reduced yellowing and improved optical properties.     

Thermogravimetric calibration of permeation tubes used for the preparation of gas standards for air pollution analysis

Sources of VOC (Volatile Organic Compounds) reference-materials at ppm and ppb levels are needed for calibration of air monitoring instruments. The permeation-tube technique is considered effective for the preparation of low concentration standards of high accuracy and stability. In this work, purpose-built PTFE permeation tubes, containing benzene, toluene, ethylbenzene, o-xylene or m-xylene (BTEX) were accurately and rapidly calibrated. Using the sensitive thermo-balance of a thermogravimetric apparatus, very low permeation rates were determined by the continuous monitoring of the tube weight loss as a function of time. Permeation rates in the range from 25 to 350 ng min(-1) were determined with precision. Thermogravimetry appears to be a rapid method for the measurement of weight loss at constant temperature, allowing rapid characterization and recalibration of permeation tubes. A detailed study on toluene, chosen as a typical case, showed that there are variations of the permeation rate in the long term. The temperature dependence of the permeation coefficient was also explored and permeation rates were shown to display an Arrhenius behavior in the temperature range 304-324 K. Thermodynamic parameters influencing the permeation were discussed.     

Comparison of different methods for generation of single-stranded DNA for SELEX processes

Single-stranded DNA (ssDNA) generation is a crucial step in several molecular biology applications, such as sequencing or DNA chip and microarray technology. Molecules of ssDNA also play a key role in the selection of ssDNA aptamers through Systematic Evolution of Ligands by EXponential enrichment (SELEX). With particular interest for this application, herein we present a comparative study of the most used methods for generation of ssDNA used in SELEX, such as asymmetric PCR, enzyme digestion and magnetic separation with streptavidin beads. In addition, we evaluate a new technique that combines asymmetric PCR and enzyme digestion with the aim to achieve the maximum efficiency in ssDNA generation. The methods studied were compared in terms of quality of ssDNA using electrophoretic analysis and generated ssDNA yields were quantitatively measured using an Enzyme-Linked OligoNucleotide Assay (ELONA).     

Optimization of process parameters for preparing a solid catalyst for bisphenol synthesis

The results of optimization of the process parameters for preparing high-performance heterogeneous catalysts for bisphenol synthesis show that the performance of the solid acid catalyst is determined by its exchange capacity, acidity, pore structure, and specific surface area. Optimum process parameters for preparing highly active solid acid catalysts were revealed.     

Thermoanalytical investigations of polyurethanes for medical purposes

Two types of laboratory synthesized polyurethanes (PU), for medical application, were investigated using the DSC method. Each PU was tested with, and without, additional purification. Commercial polyurethanes were also studied for comparison. It was found that the applied purification process influences the morphology of the polyurethanes. Changes were especially observed in the short- and long-order regions of the polymer matrix.     

Ultrafiltration tandem mass spectrometry of estrogens for characterization of structure and affinity for human estrogen receptors

Although hormone replacement therapy (HRT) is used by post-menopausal women for the relief of menopausal symptoms and the potential reduction of osteoporosis, HRT also increases their risk of Alzheimer's disease, stroke, breast cancer, and endometrial cancer. Since the majority of these effects are associated primarily with estrogen binding to only one of the estrogen receptors (ER), new assays are needed that can more efficiently evaluate ER-binding and identify ligands selective for ER-alpha and ER-beta. High performance liquid chromatography-tandem mass spectrometry (LC-MS-MS) was combined with ultrafiltration as a new method to investigate the relative binding of compounds to the ERs and to evaluate the structures of these estrogens. Mixtures of estradiol and six equine estrogens, including equilin, equilenin, 8,9-dehydroestrone, and their 17beta-hydroxyl derivatives, were assayed simultaneously to determine their relative binding to human ER-alpha and ER-beta. Estrogens containing a 17beta-OH group were found to have higher relative affinities for the estrogen receptors than their ketone analogs. In addition, 17beta-EN showed selectivity for binding to ER-beta over ER-alpha. The results were compared to the IC50 values obtained by using a conventional radiolabled estradiol competitive binding assay. Finally, the utility of negative ion electrospray tandem mass spectrometry for the unambiguous identification of these estrogen isomers was investigated. Several characteristic recyclization pathways during tandem mass spectrometry were identified, which might be useful for distinguishing related estrogens.     

Methodology for estimating removable quantities of agricultural residues for bioenergy and bioproduct use

A methodology was developed to estimate quantities of crop residues that can be removed while maintaining rain or wind erosion at less than or equal to the tolerable soil-loss level. Six corn and wheat rotations in the 10 largest corn-producing states were analyzed. Residue removal rates for each rotation were evaluated for conventional, mulch/reduced, and no-till field operations. The analyses indicated that potential removable maximum quantities range from nearly 5.5 million dry metric t/yr for a continuous corn rotation using conventional till in Kansas to more than 97 million dry metric t/yr for a corn-wheat rotation using no-till in Illinois.     

Polyrotaxane approach for synthesis of continuous beds for capillary electrochromatography

The polyrotaxane formation approach was evaluated for synthesis of continuous beds for capillary electrochromatography. This approach has the advantage of generating diverse electroosmotic and chromatographic properties without chemical reactions. The polyrotaxane derivatized continuous beds were formed adding the macrocyclic compounds to the solution of neutral acrylic monomers and crosslinker prior to the initiation of the polymerisation. Cationic and anionic derivatives of beta-cyclodextrin were used as macrocyclic compounds. Investigation of the electroosmotic properties indicated a template directed and enthalpy controlled self-assembly of the polyrotaxanes during the polymerisation of the continuous beds. This process was monomer-composition dependent and favored by the hydrophobicity of the polymeric skeleton. The morphology of the continuous beds was evaluated using high-resolution optical microscopy with CCD camera and atomic force microscopy. Reversed-phase capillary chromatography driven by electroosmosis, originating from the polyrotaxane structure, was performed using several test mixtures. Not primarily designed for the chiral chromatography the polyrotaxane derivatized continuous beds demonstrated enantioselective separation of D,L-metoprolol. The stability of the polyrotaxane derivatized continuous beds was tested. The beds demonstrated reproducible electroosmotic properties in the range from pH 4 to pH 9 (RSD=0.69%).     

Comparison of methods for outlier detection and their effects on the classification results for a particular data base

One of the drawbacks for using linear discriminant analysis (LDA) is the presence of outliers. Some methods of detecting outliers are compared and applied to a particular data base. When multivariate methods (multinormal distribution procedure and Hawkins' procedure) were applied, the two subsets produced did not differ greatly. Assumptions needed for the application of LDA were evaluated for each subset. Classification ability, feature selection and prediction ability were considered for each subset. Results for each subset were quite different. Hawkins' procedure seems the better method for detecting outliers.