Dielectrophoretic investigation of plant virus particles: Cow Pea Mosaic Virus and Tobacco Mosaic Virus

This paper reports experimental results on the dielectrophoretic (DEP) behaviour on two nonenveloped plant viruses of different geometrical shapes, namely Cow Pea Mosaic Virus (CPMV) and Tobacco Mosaic Virus (TMV). The DEP properties of carboxy-modified latex beads of the same size are also reported. The DEP properties of single particles were obtained from measurement of the frequency at which the DEP force on a particle goes to zero (the crossover frequency). The DEP behaviour of particle ensembles was also measured using image processing. The dielectric properties of the particles were evaluated from the DEP data. The surface conductance was found to be 0.3 nS for CPMV, 0.38 nS for TMV, and 0.52 nS for 27 nm diameter carboxy-latex beads. Data analysis has shown that the optimal condition for separation of TMV and CPMV is a low-conductivity suspending medium - below 1 mS/m.     

Enhancing DNA Detection Sensitivity Through a Two-Step Enrichment Method with Magnetic Beads and Droplet Evaporation

A simple and sensitive DNA detection method has been developed through a two-step enrichment process. Trace amount of target DNA in a large volume (1 mL) is selectively separated and condensed with DNA-modified magnetic beads into a small volume (5 μL) by denaturalization. Then, the pre-enriched target DNA solution (1 μL) is transferred onto a smooth hydrophobic surface, where the target DNA is further-enriched by natural sessile droplet evaporation. Using this method, the fluorescence detection sensitivity of the target DNA can be enhanced by 3 orders of magnitude and as low as 3.91 pM of the target DNA can be detected within 2 hours.     

原子转移自由基聚合法制备新型亲水作用色谱固定相及其性能评价

以自制的6.0μm单分散大孔交联聚氯甲基苯乙烯-二乙烯基苯(Poly(4-vinylbenzylchloride-co-divi-nylbenzene),PCMS/DVB)微球为基质和引发剂,CuCl和自行合成的三[(2-二甲基氨基)乙基]胺(Tris[2-(dimeth-ylamino)ethyl]amine,Me6TREN)组成混合催化体系,使4-乙烯基吡啶(4-Vinyl pyridine,4-VP)在甲苯中进行原子转移自由基聚合,制得4-乙烯基吡啶聚合物,单体4-乙烯基吡啶的接枝率为8.55%。将该聚合物与正溴丁烷反应制得新型亲水色谱固定相。在亲水作用色谱模式下,流速1 mL/min,乙腈-水为流动相可分离5种芳胺化合物和4种酚类化合物。在离子交换色谱模式下,6 mmol/L Na2CO3-5.5 mmol/L NaHCO3为淋洗液可分别分离5种无机阴离子和4种短链有机酸。结果表明,此固定相对极性化合物和无机阴离子具有良好的分离性能,是一种性能优异的亲水作用色谱固定相。     

Glass‐bead/X‐ray fluorescence analysis of earthenware body – sampling from heterogeneous earthenware

Samples of ancient earthenware were prepared in 1 : 10 glass beads for the X‐ray fluorescence quantitation of 10 major elements (Na, Mg, Al, Si, P, K, Ca, Ti, Mn, and Fe). Calibration standards of the glass beads were used with a mixture of reagents in an arbitrary ratio instead of rock standards. The calibration curves were constructed using the reported values of Japanese wares and clay materials. The adequacy of conventional sampling methods was statistically evaluated by examining the homogeneities of two shards (112 g of Jomon ware and 92 g of Yayoi ware) with respect to their crystalline phases and 10 major constituents. Both shards were found to be heterogeneous. An important finding is that in the sampling from a shard, unless at least half of the shard is homogenized, small sampling cannot represent the whole shard. The sampling was found to be only marginally reliable because the K/Ca scatter diagram for determination of provenance showed regional characteristics, and the measured analytical values showed normal (or Gaussian) distributions. Furthermore, taking eight samples or above from a shard enhances the reliability of small sampling. Copyright © 2011 John Wiley & Sons, Ltd.     

Synthesis of sodium silicate-based hydrophilic silica aerogel beads with superior properties: Effect of heat-treatment

This work demonstrates the synthesis of hydrophilic and hydrophobic high surface area silica aerogel beads with a large pore volume. Wet gel silica beads were modified and heat-treated under atmospheric pressure after modification of the surface by trimethychlorosilane (TMCS). The effects of heat treatment on the physical (hydrophobicity) and textural properties (specific surface area, pore volume, and pore size) of silica aerogel beads were investigated. The results indicated that hydrophobicity of the silica aerogel beads can be maintained up to 400 °C. The hydrophobicity of the silica aerogel beads decreased with increasing temperature in the range of 200-500 °C, and the beads became completely hydrophilic after heat treatment at 500 °C. The specific surface area, cumulative pore volume, and pore size of the silica aerogel beads increased with increasing temperature. Heating the TMCS modified bead gel at 400 °C for 1 h resulted in silica aerogel beads with high surface area (769 m²/g), and large cumulative pore volume (3.10 cm³/g). The effects of heat treatment on the physical and textural properties of silica aerogel beads were investigated by field emission scanning electron microscopy (FE-SEM), transmission electron microscopy (TEM), thermogravimetric and differential analysis (TG-DTA), Fourier-transform infrared spectroscopy (FT-IR), and Brunauer, Emmett and Teller (BET) and BJH nitrogen gas adsorption and desorption methods.     

Specific binding of a biotinylated,metallocarbonyl‐labelled dendrimer to immobilized avidin detected by diffuse‐reflectance infrared Fourier transform spectroscopy

Molecular recognition between avidin covalently immobilized at the surface of acrylic resin beads and a transition metallocarbonyl tracer of the biotin ligand was detected using diffuse reflectance infrared Fourier transform spectroscopy. Copyright © 2004 John Wiley & Sons, Ltd.     

Magneto immunofluorescence assay for diagnosis of celiac disease

A magneto immunofluorescence assay for the detection of anti-transglutaminase antibodies (ATG2) in celiac disease was developed. The ATG2 were recognized by transglutaminase enzyme immobilized on the magnetic beads and then the immunological reaction was revealed by antibodies labeled with peroxidase. The fluorescent response of the enzymatic reaction with o-phenylenediamine and H₂O₂ as substrates was correlated with anti-transglutaminase titer, showing EC50 and LOD values of 1:11,600 and 1:74,500 of antibody titers, respectively. A total number of 29 sera samples from clinically confirmed cases of celiac disease and 19 negative control samples were tested by the novel magneto immunofluorescence assay. The data were submitted to the receiver-operating characteristic plot (ROC) analysis which indicated that 8.1 U was the most effective cut-off value to discriminate correctly between celiac and non-celiac patients. The immunofluorescence assay exhibited a sensitivity of 96.6%, a specificity of 89.5% and an efficiency 93.8% compared with the commercial optical ELISA kit.     

Effect of MWCNTs Doping on the Morphology,Structure and Properties of Chitosan Beads

A series of chitosan (CS)/multi-walled carbon nanotubes (MWCNTs) composite hydrogel beads with different MWCNTs contents are prepared via a solution blending method. The effects of MWCNTs on the morphology, structure and properties of chitosan beads have been investigated. Digital pictures show that the composite beads obtained are of good morphological characteristics, and the SEM micrographs indicate that the addition of MWCNTs into CS beads made the surface of the CS/MWCNTs hydrogel beads contain much larger wrinkles. Fourier transform infrared spectra (FTIR) show that the main chain of CS bead is not changed, but there are some electrostatic interactions between CS and MWCNTs, which lead to very significant changes in the crystallization behavior of CS and MWCNTs. The thermal stability of CS/MWCNTs composites at high temperatures is increased with the existence of MWCNTs, indicating a possible electrostatic interaction between MWCNTs and CS lattices to limit the motivation of CS. The adsorption capacity of CS beads doped with a lower percentage of MWCNTs (0.02 wt%) for acid fuchsin is 112.76 mg/g, higher than that of pure CS beads (35.62 mg/g).     

Apparent Production of Enzymatically Synthesized Amylose in DMSO by Means of Calcium Alginate Hydrogel Beads/DMSO System

In this paper, we describe the apparent production of enzymatically synthesized amylose in DMSO by means of the calcium alginate hydrogel beads/DMSO system as the reaction field of the phosphorylase-catalyzed enzymatic polymerization. When the calcium alginate hydrogel beads including glucose-1-phosphate, maltoheptaose, and phosphorylase were suspended in DMSO and the system was slowly stirred at 40°C for 12 h, the reaction proceeded to produce amylose, which eluted to the DMSO solution. The obtained amylose was purified by the treatment with ion-exchange resins, and its structure was confirmed by the ¹H NMR spectrum. The time-course experiment in the present system revealed that the phosphorylase-catalyzed enzymatic polymerization was carried out for 15 min on the inside of the calcium alginate hydrogel beads and the produced amylose was gradually eluted to the surrounding DMSO solution. The comparison of the present system with the general enzymatic polymerization in aqueous buffer solution suggested that the yield and the degree of polymerization of amylose in the present system were comparable to those in aqueous buffer solution.