两种环境敏感高分子在相分离免疫分析中的比较研究

进行了两种环境敏感高分子在相分离免疫分析嗜水气单胞菌外膜蛋白(outer membrane protein, OMP)中的比较研究. 首先合成温度敏感高分子聚N-异丙基丙烯酰胺和pH敏感高分子聚(N-异丙基丙烯酰胺-甲基丙烯酸), 分别以N-羟基琥珀酰亚胺丙烯酸酯(NAS)和碳二亚胺(EDCI)作为偶联剂与抗OMP抗体(Ab)偶联形成抗体复合物(Ab-polymer), 在竞争型免疫测定中, OMP标准溶液与异硫氰酸荧光素标记OMP在均相条件下竞争性地与Ab-polymer反应, 调节外界环境分离出高分子免疫复合物沉淀, 重新溶解后荧光法定量, 两种体系的OMP浓度均在400～3000 ng/mL范围内与荧光强度呈良好线性关系, 检出限分别为84.7和39.6 ng/mL. pH敏感高分子相比于温度敏感高分子具有以下优点: 可以在37 ℃的生理温度进行免疫反应, 进一步提高了免疫反应的速度和效率; 可利用高分子本身的活性基团进行Ab的固定, 固定化效率、固定Ab的免疫反应活性较之NAS偶联法得到了提高; 有更高的检测灵敏度. 因此, pH敏感高分子更适合于作为相分离免疫分析的载体.     

新型pH敏感相分离高分子的制备及其在免疫分析中的应用

聚Ｎ 异丙基丙烯酰胺 (ＰＮＩＰ)温度敏感高分子以其独特的温度敏感性质已成功地应用于免疫分析[1～ 6] .但这类温度敏感相分离免疫分析的反应温度必须控制在ＰＮＩＰ的相转变温度 ( 31℃ )以下 ,这不可避免地会影响免疫反应速率 .ｐＨ敏感高分子是另一类对环境敏感的智能型高分子 ,在其相转变ｐＨ值附近发生沉淀与溶解的可逆性变化 .目前 ,ｐＨ敏感高分子在免疫分析中的应用并没有受到重视 ,研究得较少[7] .这主要是由于 ｐＨ敏感高分子的相转变 ｐＨ值大都在 3左右 ,在此ｐＨ条件下 ,免疫反应生成的抗原 抗体免疫复合物会受到不同程度的…     

带活性末端的热敏高分子的制备及其在荧光免疫分析中的应用

合成了带有活性末端的寡聚N-异丙基丙烯酰胺(ONIPAAm),并考察了其温度敏感性质.以ONI-PAAm作为免疫分析的载体与鼠IgG偶联,以四磺基铁酞菁为标记物,以羊抗鼠IgG抗体为分析模型,建立了竞争型热敏相分离荧光免疫分析新系统.羊抗鼠IgG抗体在0～1500ng/mL范围内与体系相对荧光强度呈良好的线性关系,检测限为2ng/mL.     

温度和pH敏感P（NIPA／AA）／黏土互穿网络水凝胶的辐射合成与表征

以N-异丙基丙烯酰胺(NIPA)和丙烯酸(AA)为聚合单体、有机黏土作为改性剂,采用60Co-γ射线为放射源,辐射合成了P(NIPA/AA)/黏土互穿网络(IPN)水凝胶,研究了IPN的表面形貌以及AA浓度、黏土对水凝胶溶胀性能和压缩性能的影响.SEM电镜观察表明:P(NIPA/AA)共聚水凝胶的表面致密,没有明显相分离,而IPN凝胶表面疏松多孔且非连续,有明显的相分离,形成了较好的IPN结构.P(NIPA/AA)IPN水凝胶在碱性和弱碱性溶液中的溶胀率高,且其溶胀速率由网络中高分子链的松弛运动控制;而在酸性介质中,水分子的扩散为水凝胶溶胀的决定过程.P(NIPA/AA)IPN水凝胶具有良好的力学性能,加入黏土后凝胶的压缩性能参数均有不同程度的提高,水凝胶受压时只发生塑性变形,没有被破坏.     

热敏相分离荧光免疫分析乙肝表面抗原的新方法

以N-异丙基丙烯酰胺为单体,将水溶性热敏高分子聚异丙基丙烯酰胺(PNIP)和抗体偶联,用异硫氰酸荧光素标记羊抗人乙肝表面抗原抗体,建立了夹心型热敏相分离荧光免疫分析乙肝表面抗原(HBsAg)的新方法.评价了抗体在PNIP上的固定效率和非特异性吸附情况.HBsAg在0.5～100μg/mL范围内与体系荧光强度呈良好的线性关系,检出限为10ng/mLHBsAg.该方法既具有均相免疫分析的快速性,又有固相免疫分析的高灵敏度.用于乙肝病人血清中HBsAg水平的测定,结果令人满意.     

新型pH敏感高分子相分离荧光免疫分析法测定兔血清中IgG

通过将N-异丙基丙烯酰胺（NIP）、甲基丙烯酸丁酯（BMA）和甲基丙烯酸（MAA）共聚得到了一种新型的pH敏感高分子,其相转变pH（pHtr）在37℃下为6.0;当溶液pH〉6.0时,高分子溶解;pH〈6.0时,高分子很快从溶液中沉淀出来。在竞争型免疫测定中,偶联在高分子上的兔免疫球蛋白G（IgG）和标准兔IgG在溶液中竞争性地与有限量的异硫氰酸荧光素标记抗体反应,根据pHtr以下免疫复合物沉淀的特性进行分离,建立了均相免疫反应、异相分离的兔IgG新型测定方法,线性范围为100—1000μg／L;检出限为10μg/L。方法灵敏、快速且操作简便,由于pHtr较之以前合成的敏感高分子更接近于中性,分离时可降低对抗原-抗体免疫复合物造成的损坏。用于兔血清中免IgG的测量,结果令人满意。     

以萘酰亚胺衍生物基荧光高分子为载体和指示剂的 相分离免疫分析方法

以4-甲氧基-N-(2-N’,N’-二甲基氨基乙基-N’-烯丙基)萘二甲酰亚胺氯化铵(DMNAA)为荧光单体, 合成了一种pH敏感荧光高分子聚N-异丙基丙烯酰胺-4-甲氧基-N-(2-N’,N’-二甲基氨基乙基-N’-烯丙基)萘二甲酰亚胺氯化铵-N,N-二甲基氨丙基甲基丙烯酰胺[P(NIP-DMAPM-DMNAA)]. 采用共聚法将日本血吸虫抗原(SjAg)固定在P(NIP-DMAPM-DMNAA)上, 制备P(NIP-DMAPM-DMNAA)-SjAg连接物, 与日本血吸虫抗体(待测, SjAb)发生免疫反应后, 调节pH值, 使荧光高分子相变分离高分子-免疫组分连接物, 最后, 利用蛋白A对抗体的亲和性捕获P(NIP-DMAPM-DMNAA)-SjAg-SjAb, 通过测定高分子自身的荧光信号来定量 SjAb. 该新型高分子具有良好的荧光特性, 对pH响应快速, 37 ℃下相转变pH值为7.2, 分离免疫复合物时造成的损害低. 与传统相分离免疫分析比较, 新方法通过高分子相变分离和蛋白A捕获双重分离作用, 消除了非特异性组分和未反应的特异性免疫成分等的干扰; 利用高分子自身的荧光信号检测, 无须另外的标记物, 大大提高了免疫分析的简便性. 以日本血吸虫抗体为分析对象, 测得线性范围为1～1500 ng/mL, 抗体检出限为1.3 ng/mL, 相对标准偏差为3.6% (n＝10), 结果令人满意.     

pH值敏感相分离特性的蛋白质酶解试剂研究

通过DEC/NHS偶联反应将胰蛋白酶(Trypsin)连接到具有pH值敏感性的壳聚糖(CS)链上.Trypsin-CS偶联物保留了CS的pH值敏感相分离特性及Trypsjn的酶催化活性.浊度滴定实验表明,此偶联物的临界相分离pH值(CPSP)仍保持在偏中性范围内,并且随CS的分子量降低而略有上升.这种偏中性的CPSP值...     

等规聚丙烯/二元乙丙橡胶合金相分离对结晶动力学的影响

用小角激光光散射(SALLS)、相差显微镜(PCM)、示差扫描量热仪(DSC)和偏光显微镜(POM)研究了聚丙烯/二元乙丙橡胶(iPP/EPR)共混体系的相分离行为和等温结晶行为.发现iPP/EPR(50/50,W/W)发生的液-液相分离遵循spinodal机理.通过Cahn-Hilliard方程求得了不同实验温度下iPP/EPR的表观扩散系数(Dapp)以及spinodal温度(Ts).考察了不同相分离程度的iPP/EPR体系结晶动力学,发现延长相分离时间(tps)或提高相分离温度(Tps)均会导致半结晶时间(t1/2)增大,即结晶速率降低.这被归于EPR成核作用的降低.动力学分析结果表明Avrami模型适用于描述该体系的等温结晶过程,其结晶机理基本不受相分离程度的影响,结晶均以瞬时成核和三维生长为主.     

反应诱导相分离过程的超声波在线跟踪

利用高频超声波对多相体系的界面Rayleigh散射作用实现了反应诱导相分离过程的在线跟踪.新技术用来跟踪环氧树脂在聚乙二醇介质中的固化反应,研究体系在不同浓度、不同反应介质、不同固化剂用量以及不同反应温度下的相分离过程.在对旋节线相分离模式深入分析的基础上,提出了双函数模型来描述相分离过程.将超声波散射强度与相分离速率函数以及相离散速率函数相结合,所得到的数学模型合理解释了超声波跟踪数据.跟踪技术发现,反应体系的浓度对相分离的速率和相结构的离散程度有很大影响,高浓度下的固化反应抑制了相分离,使相结构保持高的连续性;在高浓度和PEG2000介质中发现了l(t)滞后现象,证明了旋节线相分离的分离机理;环氧树脂与固化剂重量比为4/1时,相分离达到最佳状态;升高反应温度,固化反应速率提高快于相分离速率的提高,相分离被固化反应所抑制.新的技术将散射强度与微相结构中的离散程度对应起来,从而能实时分析相分离过程中微相结构的变化过程,为相分离的控制提供实验依据.     

Pervaporation dehydration of isopropanol with chitosan membranes

Homogeneous and composite chitosan based membranes were prepared by the solution casting technique. The membranes were investigated for the pervaporation dehydration of isopropanol-water systems. The effects of feed concentration and temperature on the separation performance of the membranes were studied. In terms of the pervaporation separation index (PSI), the composite membrane was more productive than the homogeneous membrane for pervaporation of feed with high isopropanol content. It was observed that permeation increased and the separation factor decreased with the temperature. Modification of the homogeneous chitosan membrane by chemical crosslinking with hexamethylene diisocyanate improved the permselectivity but reduced the permeation rate of the membrane.     

Characterization of low-energy chlorophylls in the PSI-LHCI supercomplex from Chlamydomonas reinhardtii. A site-selective fluorescence study

Almost all photosystem I (PSI) complexes from oxygenic photosynthetic organisms contain chlorophylls that absorb at longer wavelength than that of the primary electron donor P700. We demonstrate here that the low-energy pool of chlorophylls in the PSI-LHCI complex from the green alga Chlamydomonas reinhardtii, containing five to six pigments, is significantly blue-shifted (A(max) at 700 nm at 4 K) compared to that in the PSI core preparations from several species of cyanobacteria and in PSI-LHCI particles from higher plants. This makes them almost isoenergetic with the primary donor. However, they keep the other characteristic features of "red" chlorophylls: clear spectral separation from the bulk chlorophylls, big Stokes shift revealing pronounced electron-phonon coupling, and large homogeneous and inhomogeneous broadening of approximately 170 and approximately 310 cm(-1), respectively.     

Combining the benefits of homogeneous and heterogeneous catalysis with tunable solvents and nearcritical water

The greatest advantage of heterogeneous catalysis is the ease of separation, while the disadvantages are often limited activity and selectivity. We report solvents that use tunable phase behavior to achieve homogeneous catalysis with ease of separation. Tunable solvents are homogeneous mixtures of water or polyethylene glycol with organics such as acetonitrile, dioxane, and THF that can be used for homogeneously catalyzed reactions. Modest pressures of a soluble gas, generally CO?, achieve facile post-reaction heterogeneous separation of products from the catalyst. Examples shown here are rhodium-catalyzed hydroformylation of 1-octene and p-methylstyrene and palladium catalyzed C-O coupling to produce o-tolyl-3,5-xylyl ether and 3,5-di-tert-butylphenol. Both were successfully carried out in homogeneous tunable solvents followed by separation efficiencies of up to 99% with CO? pressures of 3 MPa. Further examples in tunable solvents are enzyme catalyzed reactions such as kinetic resolution of rac-1-phenylethyl acetate and hydrolysis of 2-phenylethyl acetate (2PEA) to 2-phenylethanol (2PE). Another tunable solvent is nearcritical water (NCW), whose unique properties offer advantages for developing sustainable alternatives to traditional processes. Some examples discussed are Friedel-Crafts alkylation and acylation, hydrolysis of benzoate esters, and water-catalyzed deprotection of N-Boc-protected amine compounds.     

Molecular interface effect of heterogeneous molecular junctions consisting of nonfluorinated and fluorinated phthalocyanines

We report the tunneling behavior of homogeneous and heterogeneous molecular junctions using p-type molecules of iron phthalocyanine (FePc), phthalocyanine (H(2)Pc), and copper(II) octaalkoxyl substituted phthalocyanine (CuPcOC8) and n-type molecule of copper hexadecafluorophthalocyanine (F(16)CuPc). The molecular films formed on the electrode surfaces were inspected by X-ray photoelectron spectroscopy (XPS). The measured characteristic tunneling curves of single-component phthalocyanines revealed comparable energy gaps for homogeneous tunneling junctions using the photoemission method. In contrast, for the heterogeneous tunnel junctions of mixed phthalocyanines including fluorinated phthalocyanine a distinctive offset of the energy gaps to the positive bias voltage direction can be clearly identified. It is suggested that the substitution of phthalocyanines and surface affinity of phthalocyanines could contribute to the controlled phase separation within the heterogeneous tunneling junctions. The apparent shift of the tunneling spectra is attributed to the existence of an internal electric field originated with the phase separation of the binary mixture of p-type and n-type phthalocyanines within the tunneling junction.     

全氟烷基磺酸盐和全氟烷基磺酰亚胺盐的多相化催化研究

传统的Lewis酸催化剂在环境的压力下受到挑战,全氟烷基磺酸盐和全氟烷基磺酰亚胺盐作为均相、高效的Lewis酸催化剂在有机合成中受到人们的关注.为了简化分离操作,人们对全氟烷基磺酸盐和全氟烷基磺酰亚胺盐的多相化进行了研究,并已取得巨大进展.本文综述了全氟烷基磺酸盐和全氟烷基磺酰亚胺盐分别负载在有机载体、无机载体以及离子液体上的多相化催化最新研究进展,简要概括了其制备方法和催化活性,并对其催化应用前景进行了展望.     

Investigation of the Scope of Heterogeneous and Homogeneous Procedures for Preparing Magnesium Chelates of Porphyrins, Hydroporphyrins, and Phthalocyanines

A simple method has been developed for metalation of porphyrinic compounds under homogeneous conditions at room temperature using a stable ethereal solution of MgI(2) and N,N-diisopropylethylamine. A previously developed heterogeneous procedure employs a mixture of a magnesium halide and a nonnucleophilic amine in a noncoordinating solvent at room temperature. The scope of the heterogeneous and homogeneous magnesium insertion procedures has been investigated across a family of 19 porphyrinic compounds, including synthetic porphyrins, synthetic or naturally occurring chlorins, and organic-soluble phthalocyanines. The rate of magnesium insertion increased in the series phthalocyanines < chlorins < porphyrins, which parallels the basicity of the ligands. Though phthalocyanines have the smallest core size, the magnesium phthalocyanines were far more stable than magnesium porphyrins to acid-induced demetalation. The heterogeneous method is broadly applicable to porphyrins, chlorins, and phthalocyanines. The homogeneous method is generally slower than the heterogeneous method, though both afford rapid metalation of most porphyrins, including electron-deficient, peripherally coordinating, or facially encumbered meso-substituted tetraarylporphyrins, and the beta-substituted octaethylporphyrin. Chlorin e(6) trimethyl ester and methyl pyropheophorbide a were metalated cleanly under homogeneous but not heterogeneous conditions, while pheophytin a failed with both methods. The homogeneous method failed altogether with phthalocyanines. Several methods in magnesium chemistry have been developed that augment these procedures, including a mild synthesis of tetraphenylchlorin and a streamlined separation of porphyrin, chlorin, and bacteriochlorins based on selective formation of the magnesium chelates. Collectively, these methods should broaden the scope of model systems based on magnesium chelates of porphyrinic compounds.     

Hydroformylation of Olefins by a Rhodium Single‐Atom Catalyst with Activity Comparable to RhCl(PPh3)3

Homogeneous catalysts generally possess superior catalytic performance compared to heterogeneous catalysts. However, the issue of catalyst separation and recycling severely limits their use in practical applications. Single‐atom catalysts have the advantages of both homogeneous catalysts, such as “isolated sites”, and heterogeneous catalysts, such as stability and reusability, and thus would be a promising alternative to traditional homogeneous catalysts. In the hydroformylation of olefins, single‐atom Rh catalysts supported on ZnO nanowires demonstrate similar efficiency (TON≈40000) compared to that of homogeneous Wilkinson's catalyst (TON≈19000). HAADF‐STEM and infrared CO chemisorption experiments identified isolated Rh atoms on the support. XPS and XANES spectra indicate that the electronic state of Rh is almost metallic. The catalysts are about one or two orders of magnitude more active than most reported heterogeneous catalysts and can be reused four times without an obvious decline in activity.     

RNA–DNA Chimeras in the Context of an RNA World Transition to an RNA/DNA World

The RNA world hypothesis posits that DNA and proteins were later inventions of early life, or the chemistry that gave rise to life. Most scenarios put forth for the emergence of DNA assume a clean separation of RNA and DNA polymer, and a smooth transition between RNA and DNA. However, based on the reality of “clutter” and lack of sophisticated separation/discrimination mechanisms in a protobiological (and/or prebiological) world, heterogeneous RNA–DNA backbone containing chimeric sequences could have been common—and have not been fully considered in models transitioning from an RNA world to an RNA–DNA world. Herein we show that there is a significant decrease in Watson–Crick duplex stability of the heterogeneous backbone chimeric duplexes that would impede base‐pair mediated interactions (and functions). These results point to the difficulties for the transition from one homogeneous system (RNA) to another (RNA/DNA) in an RNA world with a heterogeneous mixture of ribo‐ and deoxyribonucleotides and sequences, while suggesting an alternative scenario of prebiological accumulation and co‐evolution of homogeneous systems (RNA and DNA).     

Ethane/ethylene adsorption on carbon nanotubes: temperature and size effects on separation capacity

We present the results of Monte Carlo simulations of the adsorption of single-component ethane and ethylene and of equimolar mixtures of these two gases on bundles of closed, single-walled carbon nanotubes. Two types of nanotube bundles were used in the simulations: homogeneous (i.e., those in which all the nanotubes have identical diameters) and heterogeneous (those in which nanotubes of different diameters are allowed). We found that at the same pressure and temperature more ethane than ethylene adsorbs on the bundles over the entire range of pressures and temperatures explored. The simulation results for the equimolar mixtures show that the pressure at which maximum separation is attained is a very sensitive function of the diameter of the nanotubes present in the bundles. Simulations using heterogeneous bundles yield better agreement with single-component experimental data for isotherms and isosteric heats than those obtained from simulations using homogeneous bundles. Possible applications of nanotubes in gas separation are discussed. We explored the effect of the diameter of the nanotubes on the separation ability of these sorbents, both for the internal and for the external sites. We found that substrate selectivity is a decreasing function of temperature.     

同质编织管增强型聚丙烯腈中空纤维膜研究

利用二维编织技术将聚丙烯腈(PAN)纤维编织成中空编织管,以聚丙烯腈为成膜聚合物,以聚乙二醇为成孔剂,配制铸膜液,采用同心圆纺丝法制备同质编织管增强型聚丙烯腈中空纤维膜.研究结果表明,所得同质编织管增强型聚丙烯腈中空纤维膜的表面分离层具有类似于非对称膜的结构,铸膜液可渗入编织管纤维束中;随着编织管编织节距的增大,同质编织管增强型聚丙烯腈中空纤维膜表面分离层厚度减小,同时膜的平均孔径增大,膜的纯水通量随之增大;铸膜液渗入编织管纤维束的现象未影响膜的通透性能;编织管的断裂强度最大可达100 MPa以上.通过水浴振荡、超声波水浴振荡及等力拉伸3种方法测试了同质编织管增强型中空纤维膜和异质编织管增强型中空纤维膜中编织管与表面分离层之间的界面结合性能,结果表明前者的界面结合性能优于后者.