Compressed CO2-enhanced solubilization of 1-butyl-3-methylimidazolium tetrafluoroborate in reverse micelles of Triton X-100

We carried out the first study about the effect of a compressed gas on the properties of reverse micellar solutions with ionic liquid (IL) polar cores. And the properties of compressed CO2/cyclohexane/1-butyl-3-methylimidazolium tetrafluoroborate ([bmim][BF4])/Triton X-100 (TX-100) system were investigated at 288.2, 293.2, 298.2, 308.2 K and different pressures by using phase behavior measurement, small-angle x-ray scattering, and UV-Vis techniques. The concentration of the surfactant in the solution was 0.3 mol/l (M). It was found that compressed CO2 could enhance solubilization of the IL in the reverse micelles considerably at suitable pressures, and formation of the reverse micelles could be controlled easily by pressure. Increase of CO2 pressure resulted in decrease of the micellar sizes at fixed [bmim][BF4]-to-surfactant molar ratios (w), and the size of the reverse micelles increased with the increase of w values. The polarity of the IL cores increased continuously with increasing w value.     

Effect of compressed CO2 on the chloroperoxidase catalyzed halogenation of 1,3-dihydroxybenzene in reverse micelles

The effect of compressed CO2 on the specific activity of chloroperoxidase (CPO) to catalyze the chlorination of 1,3-dihydroxybenzene in cetyltrimethylammonium chloride (CTAC)/H2O/octane/pentanol reverse micellar solution was studied. The results show that the specific activity of the enzyme can be enhanced significantly by compressed CO2, and the specific activity can be tuned continuously by changing pressure. The mechanism for the specific activity enhancement of the enzyme by CO2 was also studied. We believe that compressed CO2 can be utilized to tune some other enzyme catalytic reactions in different reverse micellar systems with potential advantages.     

CD4+T细胞亚群在MDS与AML中的变化比较和临床意义

目的通过比较骨髓增生异常综合征和急性髓系白血病患者Thl、Th2、Thl7和Treg细胞的数量变化,以观察两种疾病的细胞免疫状态,分析其临床意义。方法采用流式细胞仪检测难治性贫血组(RA)20例,难治性贫血伴原始细胞增多组(RAEB)25例;AML组15例患者外周血中Thl、Th2、Thl7和Treg细胞的水平,采用SPSS 13.0统计学软件进行数据分析处理。结果相较于正常对照组,Th1、Th17细胞和Th1/Th2在MDS-RA组均升高(P<0.05),MDS-RAEB组和AML组均减低(P<0.05);Th2细胞比例MDS-RA组减低(P<0.05),MDS-RAEB组和AML组升高(P<0.05);而Treg细胞MDS-RA组比例无统计学意义(P>0.05),MDS-RAEB组和AML组升高(P<0.05)。相较于MDS-RA组,MDS-RAEB组Th1、Th17细胞比例和Th1/Th2减低(P<0.05),而Th2和Treg细胞比例升高(P<0.05)。与MDS-RAEB组相比,AML组Th1细胞比例减低(P<0.05),Th2和Treg细胞升高(P<0.05),而Th17细胞和Th1/Th2无统计学意义(P>0.05)。结论 Th细胞向Th1型细胞极化,Th17细胞显著性升高为主要表现的Th1/Th2细胞因子网络的破坏使在MDS的早期阶段产生过多的造血抑制因子可能是造血功能衰竭的主要原因;Th细胞向Th2型细胞极化,Th17细胞减低,Treg细胞比例增高在MDS晚期阶段及AML中引起异常克隆细胞的积聚可能是造血功能衰竭的主要原因。     

Effects of cross-links, pressure and temperature on the thermal properties and glass transition behaviour of polybutadiene

The thermal conductivity κ, heat capacity per unit volume ρc(p) and glass transition behaviour under pressure have been established for medium and high vinyl content polybutadiene PB with molecular weights 2600 and 100,000 and their highly cross-linked (ebonite) states obtained purely by high-pressure high-temperature treatments. Cross-linking eliminates the glass transitions and increases κ by as much as 50% at 295 K and 1 atm, and decreases ρc(p) to a limiting level close to that of the glassy state of PB, which is reached before the ultimate cross-link density is achieved. The pressure and temperature behaviours of κ are strongly changed by cross-links, which increases the effect of temperature but decreases the effect of pressure. We attribute these changes to a cross-linked induced permanent densification and consequential increase of phonon velocity simultaneously as conduction along polymer chains is disrupted. The glass transition temperatures for a time scale of 1 s are described to within 0.5 K by: T(g)(p) = 202.5 (1 + 2.94 p)(0.286) and T(g)(p) = 272.3 (1 + 2.57 p)(0.233) (p in GPa and T in K) up to 1 GPa, for PB2600 and PB100000, respectively, and can be estimated for medium and high vinyl content PBs with molecular weights in between by a constant, pressure independent, shift in temperature.     

Fabrication of flowerlike polymer superstructures using polymer/zeolite composites prepared with supercritical CO2

We report a route to the fabrication of unique flowerlike polymer superstructures with uniform petals at the nanoscale. In this method, polymer/zeolite composite is first prepared by loading corresponding monomer and initiator into the channels of the host zeolite with the aid of supercritical (SC) CO2, followed by thermal polymerization of monomers in the channels of the zeolite. The resultant polymer/zeolite composite is then treated with HF aqueous solution to allow the self-aggregation of the polymer and the inorganic components to form the polymeric layers and inorganic layers. Unique microscale flowerlike polymer superstructures are obtained after further treatment with HF aqueous solution. Different techniques, such as scanning electron microscopy (SEM), X-ray diffraction (XRD), transmission electron microscopy (TEM), Fourier transform infrared spectroscopy (FTIR), and thermogravimetry (TG), have been used to characterize the microflowers.     

Synthesis of cross-linked enzyme aggregates (CLEAs) in CO2-expanded micellar solutions

A new method to prepare the cross-linked enzyme aggregates (CLEAs) was developed. Through cross-linking the enzyme (Trypsin) aggregates, which was precipitated from the CO2-expanded reverse micellar solutions, dendritic CLEAs were obtained. The sizes of the CLEAs prepared by this new method were nanometer order of magnitudes and could be tuned by changing the water-to-surfactant ratio (w0) and the concentration of enzyme in the reverse micellar solution. The diameter of CLEAs increased with increasing w0 value of reverse micelles and the concentration of Trypsin. The activity of CLEAs obtained by this method is improved in contrast to those obtained by the conventional method. This method has some advantages in applications and can be easily applied to the synthesis of other cross-linked enzyme aggregates.     

Simultaneous electrochemical immunosensing of alpha-fetoprotein and prostate specific antigen using a glassy carbon electrode modified with gold nanoparticle-coated silica nanospheres and decorated with Azure A or ferrocenecarboxylic acid

We describe an electrochemical immunosensor for the simultaneous determination of alpha-fetoprotein (AFP) and prostate specific antigen (PSA) via a modified glassy carbon electrode. Silica nanoparticles (200–300 nm i.d.) with good monodispersity and uniform shape were synthesized, and the following species were then consecutively immobilized on their surface: gold nanoparticles (AuNPs; 5–15 nm i.d.), secondary antibody (Ab₂) and the redox-probes Azure A or ferrocenecarboxy acid (Fc). In parallel, two types of primary antibodies (Ab₁) were co-immobilized on the surface of the dissolved reduced graphene oxide sheets (rGO) that were also decorated with AuNPs. In the presence of antigens (AFP or PSA), the Ab₂/Si@AuNPs carrying Azure A and Fc are attached to the AuNP/rGO conjugate via a sandwich type immunoreaction. Differential pulse voltammetry (DPV) was employed to measure the resulting changes in the signal of Fc or Azure A. Two well-resolved oxidation peaks, one at −0.48 V (corresponding to Azure A) and other at + 0.12 V (corresponding to Fc; both vs. SCE) can be observed in the DPV curves. Under optimal conditions, AFP and PSA can be simultaneously determined in the range from 0.01 to 25 ng mL‾¹ for AFP, and from 0.012 to 25 ng mL‾¹ for PSA. The detection limits are 3.3 pg mL‾¹ for AFP and 4.0 pg mL‾¹ for PSA (at a signal-to-noise ratio of 3). The method was applied to (spiked) real sample analysis, and the recoveries are within 96.0 and 107.2 % for PSA, and within 100.9 and 105.8 % for AFP, indicating that this dual immunosensor matches the requirements of clinical analysis.

(A) Two types of signal labels preparation process. (B) The immunosensor preparation and detection process.

     

Determination of Pitavastatin in Human Plasma by LC–MS–MS

A simple and rapid LC–MS–MS assay was developed and validated for the quantitative determination of pitavastatin in human plasma. Sample pretreatment involved simple protein precipitation by addition of acetonitrile. Separation was on an Agilent 1.8 μm Zorbax SB-C18 column (150 mm × 4.6 mm) at 25 °C using isocratic elution with methanol–0.1% formic acid in water (85:15, v/v) at a flow rate of 0.4 mL min^?1. Detection was performed using electrospray ionization in positive ion multiple reaction monitoring mode by monitoring the ion transitions m/z 422.0 → 290.1 for pitavastatin, and m/z 330.1 → 192.1 for paroxetine (IS). LC–MS–MS was found to improve the quantitation of pitavastatin in plasma and was successfully applied in pharmacokinetic studies.