分子烙印传感器的研究进展

分子烙印技术是制备具有选择性分子识别能力的聚合物的新兴技术,其应用之一是将分子烙印聚合物用作分析化学中化学传感器的识别元件。本文综述了分子烙印技术的原理方法及其在传感器方面的应用,评述了分子烙印传感器的发展方向,展望了其在有机磷化合物检测中的应用前景。     

分子烙印技术在分析化学中的应用

分子烙印技术是一种制备具有特定选择性和亲合性的分子识别材料的技术。它在烙印分子存在的情况下,功能性单体与交联剂共聚制得高交联的聚合物网络,移去烙印分子后就得到了对烙印分子记忆效应的分子烙印聚合物。它在分析化学,催化和有机合成等领域都具有应用价值。该文主要介绍了烙印聚合物在分析化学中的应用研究,着重于它在色谱技术中的应用,尤其是在毛细管电色谱中的应用。最后对该技术的发展前景进行了讨论。     

一种具有高度选择性的技术——分子烙印

分子烙印技术作为一个新概念被提出来 ,虽然国外已有一部分人在这方面作出了一些研究 ,但国内这方面的报道却很少 ,本文从自组装方式和预聚合方式两种合成分子烙印聚合物的模型 ;烙印分子、功能性聚合物单体及聚合条件的选择 ;分子烙印聚合物的特点、应用及展望等作了评述     

一种具有高速选择性的技术—分了烙印

分子烙印技术作为一个新概念被提出来,虽然国外已有一部分人在这方面作出了一些研究,但国内这方面的报道却很少,本文从自组装方法和预聚合方法两种合成分子烙印聚合物的模型,烙印分子、功能性聚合物单体及聚合条件的选择,分子烙印聚合物的特点,应用展望等作了评述。     

分子烙印技术简介

分子烙印技术的基本思想是源于人们对抗体—抗原或酶的专一性的认识 ,即一种抗体只能针对一种抗原 ,一种酶只能选择性的催化一种或固定的几种底物 ,而分子烙印技术则通过人工的方法合成与目标分子耦合的大分子化合物 :以目标分子为模板 ,将具有结构互补的功能化聚合物单体分子通过共价键或非共价键的方式与模板分子结合 ,加入单体进行聚合反应 ,反应完成后将模板分子提取出来后形成具有空穴的能识别模板分子的高分子。用这种基于仿生方法合成的大分子聚合物即为分子烙印聚合物 ,它与模板分子的位置 ,形状 ,官能团互补[4 ] ,对模板分子具有高…     

对硫磷分子烙印传感器的制备及应用

对硫磷分子烙印传感器的制备及应用;分子烙印传感器;对硫磷;纳米TiO2;微分脉冲伏安法;液相沉积     

分子烙印聚合物固定相分离咖啡因和茶碱的研究

分子烙印是一种新兴的分子识别技术,利用该技术可制备对烙印分子具有“预定”识别能力的高分子聚合物,即分子烙印聚合物（MIP）,从而可以对性质和组成相近的组如对映体等进行分离^[1,2],咖啡因与茶碱的分子烙印聚合物的制备以及二者分析已有报道^[3-9],但存在两种完全相反的结论。一种观点认为,即使以咖啡因为烙印分子,所制备的聚合物对咖啡因分子的选择性吸附能力也小于茶碱^[3-6]。而另一种观点则认为,在一定条件下,如以咖啡因分子为烙印分子的烙印聚合物对咖啡因分子具有更强的吸附能力^[7-9]。本文分别采用茶碱和咖啡因作为烙印分子,以甲基丙烯酸等为功能单体,在不同条件下制备了多种非共价型分子烙印聚合物,并系统地考察了其作 为HPLC固定相对咖啡因和茶碱的分离能力,同时也对烙印分子应具备的条件加以探讨。     

分子烙印聚合物作为高效毛细管电泳添加剂的研究

分子洛印聚合物（molecular imprinted polymer)是一种高选择的有分子记忆效应的主体分子,通常在非极性环境中制备和应用。该文在极性溶剂中利用离子化作用和疏水作用制备了非共价的分子烙印聚合物,并将其作为高效毛细管电泳流动相添加剂;在含水缓冲溶液条件下,研究了单体种类、分子烙印聚合物颗粒度和含量、缓冲溶液pH值以及分离电压对分子烙印聚合物识别模板分子的影响。结果证明了在质子溶剂中制备和应用非共价分子烙印聚合物是可行的。     

一种新的膦酸酯分子烙印电化学传感器

基于溶胶-凝胶和分子烙印技术,以对-特丁基杯[6]芳烃为功能单体制备了O,O-二甲基-(2,4-二氯苯氧基乙酰基)(3′-硝基苯基)次甲基膦酸酯(φ-NO2)分子烙印电化学传感器,并考察了该化合物在传感器上的电化学行为。该传感器对φ-NO2具有较好的选择性和较高的灵敏度。在优化条件下,发现峰电流和该有机膦酸酯的浓度在1.0×10-8~2.0×10-5mol/L范围内具有良好的线性关系(r=0.9994);其检出限达1.0×10-9mol/L。将此传感器用于白菜样品中φ-NO2的测定,结果令人满意。     

分子烙印聚合物为固定相分离和识别磺胺类药物

以磺胺甲噁唑为模板分子,采用原位聚合法制备了具有特定识别性能的棒状分子烙印聚合物。作为高效液相色谱的固定相实现了磺胺甲噁唑与其结构类似物的分离。磺胺甲噁唑烙印聚合物和目标分子之间的相互作用除了特异性的氢键作用外,也存在着疏水作用。同时考察含水量、流速对分离的影响,论证了分子烙印聚合物选择性专一的作用原理。结果表明,这种棒状聚合物对模板分子及其类似物有很好的分离能力。     

基于碱金属和过渡金属修饰铁矿石载氧体的煤催化燃烧

煤气化反应是煤化学链燃烧过程的控制步骤,其反应速率慢。采用碱金属Na和过渡金属Ni对铁矿石载氧体进行修饰,在流化床反应器上研究了Na、Ni负载量和反应温度对煤化学链催化燃烧的影响。结果表明,在920℃时,Na-铁矿石的催化活性高于Ni-铁矿石,随着Na、Ni负载量的增加,煤化学链燃烧的反应速率加快,气体反应产物浓度达到峰值的时间缩短,反应后期气体产物的衰减速率变大,整个反应期间CO体积浓度明显减少,而CO₂、H₂体积浓度增大。当Na、Ni负载量均为6%时,两者进行比较分析,Ni在960℃时对煤化学链的催化燃烧效果最为显著,碳转化率高达92.7%,高于纯铁矿石约15.5%,而在800~920℃下,催化效果不明显;Na在800~960℃对煤气化反应的催化效果均较显著。SEM-EDX分析显示,反应结束后,Na-铁矿石载氧体表面Na盐流失严重,而Ni-铁矿石表面Ni盐负载较好。     

不同材料滤嘴对卷烟主流烟气中挥发性羰基化合物截滤性能的研究

吸烟是引起肺癌及相关疾病的主要原因[1]。挥发性羰基化合物(如甲醛、乙醛、丙醛、丙酮、丙烯醛、巴豆醛、丁酮和丁醛)是卷烟主流烟气中含量较高的一类有害成分,含量从几十到几百微克不等[2-3]。这些挥发性羰基化合物特别是甲醛、丙烯醛及巴豆醛具有纤毛毒性,与氰化氢和氨一起,     

NO双分子和二聚体与Cu2作用的理论计算

采用密度泛函理论(DFT)中的B3LYP方法，在Lanl2DZ基组下，对NO双分子和二聚体与铜原子簇相互作用的结构进行了研究. 结果表明，NO可以在铜表面相邻的两个铜原子上形成稳定的双分子吸附和二聚体吸附，而在双分子吸附形式中NO以氮原子吸附在铜上的构型最稳定，且顶点吸附的稳定性不如非顶点吸附形式.在二聚体吸附形式中， N－N键被加强，而N－O键被削弱的程度大于双分子吸附形式，说明二聚体的形成有利于NO在金属铜表面的直接分解.同时电荷布居分析表明，单重态的二聚体与铜作用时，铜原子上的平均电荷达到0.66 e,说明在这种吸附形式中铜被离子化的倾向较大，而且这种吸附形式最有利于NO的分解.这些结果说明NO经二聚体形式在铜表面直接催化分解是可行的.     

Electrooxidation and adsorption of oligoelthylene glycols on platinized platinum electrode

The trends in adsorption and oxidation of oligoethylene glycols (OEG), namely, di-, tri-, and tetraethylene glycol, on a Pt/Pt electrode are studied. Using a combination of methods of open-circuit potential shifts at the adsorption of organic species and anodic voltammetric curves, it is established that the OEG adsorption on a Pt/Pt electrode is accompanied by hydrogenation, dehydrogenation, and partial destruction of molecules and also that the amount and composition of accumulated adsorbate depend on the initial adsorption potential and the polymer structure. The OEG oxidation on a platinum electrode is considerably hindered as compared with ethylene glycol. The reaction rate decreases with an increase in the OEG molecular mass and is largely limited by the adsorption of molecules on the electrode surface, which is evidenced by the weak dependence of the rate on the potential in the double layer region.     

Physico-chemical aspects of polyethylene processing in an open mixer. Part 17. Effect of oxygen availability

The gas in contact with polyethylene has considerable impact on its oxidation. The rate of oxidation product formation is mostly larger with oxygen blanketing than in air. Similarly, the rate in air is larger than that under nitrogen blanketing. Moreover, the relative effect of the surrounding gas is depending heavily on the particular oxidation product considered. The effect on the alcohol concentration on passing from air to pure oxygen is the same as that on the hydroperoxide concentration. It is only under pure nitrogen that alcohol formation is relatively more affected than hydroperoxide formation. The overall carbonyl groups as well as the ketones show the expected ranking, i.e. faster rate in pure oxygen than in air and faster rate in air than under pure nitrogen. However, carboxylic acids are formed much faster in oxygen than in air. For the acids the results in air and under nitrogen are significantly closer in the initial stages of processing than the results obtained under pure oxygen. This is different for γ-lactones for which formation is faster in oxygen than in air where it is faster than under nitrogen. With trans-vinylene groups the situation is opposite to that observed for carboxylic acids: the rate of formation is close for the experiments performed under air and under oxygen and significantly faster than under nitrogen. The results for hydroperoxides, alcohols and ketones are easily interpreted taking into account the kinetics developed in previous work. Fitting the data to the heterogeneous kinetics shows the effect of the oxygen concentration on this kinetics. It is especially unexpected with respect to its impact on the initiation rate. It is discussed taking into account various possibilities. The only one that is compatible with all the data envisages chain initiation resulting from interaction of oxygen with strained polymer molecules.     

The electroreduction of formaldehyde on tin and indium

The electrochemical behavior of formaldehyde on tin and indium cathodes has been studied over a wide range of pH (0.4–13), concentrations (1×10^?3 to 6×10^?1M) and potentials. Potentiostatic, potentiodynamic, ac impedance and photoe mission techniques were used to determine the kinetics of the reaction and to postulate a mechanism. The behavior on indium is similar to that reported on mercury cathodes. Tafel slopes are about 65 to 80 mV/decade. This value indicates that protonation of a reaction intermediate is the rate determining step of the reaction. The value of the slope depends slightly on concentration and pH because of adsorption under Temkin conditions. The reaction order with respect to formaldehyde is close to 1 in the limiting current region, but smaller in the Tafel region. The effect of formaldehyde on tin in neutral and alkaline solutions is to decrease the hydrogen overpotential by about 0.5 V, without affecting the Tafel slope. The rate of formaldehyde reduction is very slow. An explanation for this catalytic effect is postulated, based on the adsorption of formaldehyde-related species on the electrode surface. Formation of bridge-type complexes is also postulated. The exact nature of the adsorbed species is unknown. Preliminary results indicate that the behavior of formaldehyde on lead is similar to that on tin. The influence of this species on the reduction of formic acid on tin and lead is discussed.     

A study on the effects of ozone treatment on the properties of raw and degummed mulberry silk fabrics

Ozone is a powerful oxidizing agent and is widely used in various applications, which includes bleaching of cotton. Its application on the processing of silk is non-existent. Research studies on degumming and bleaching of silk reveal that almost no work involving ozone has been carried out. Therefore a study was carried out to understand the effects of process parameters namely wet pickup, pH and time in the ozone treatment of raw and degummed mulberry and tassar silk fabrics on their properties. This paper reports on the effects of ozone treatment on the mulberry silk fabrics. The study was extended with a view to compare the ozone treatment with soap degumming and hydrogen peroxide treatment carried out on raw and degummed mulberry silk fabrics, respectively. The treatment results in increase in yellowness index and amino group content and decrease in breaking strength and elongation, weight and flexural rigidity. The results obtained are substantiated with tyrosine content, scanning electron micrographs and infrared spectroscopy of the treated materials. The effect of pH on the treatment is maximum up to pH 4 and then decreases. The treatment is more severe when the wet pickup used is 50% compared to that of 10 and 100%. With respect to treatment time, though the severity increases with time, it is maximum during the first 10 min of the treatment. Soap degumming of raw silk fabric results in lower yellowness index and flexural rigidity and lesser loss in breaking strength and elongation compared to that of ozone treated material. There is not much of difference between ozone and hydrogen peroxide treatments of degummed silk fabric except for the lower yellowness index obtained in the latter case.     

The metal–solution interface

This article reviews our present understanding of the metal–solution interface, drawing comparisons between it and the metal–gas interface. The chief difference between these two systems is the solvent, which has a profound effect on the physics and chemistry of the interface. The solvent is never entirely inert, and if polar, as water is, will adsorb on the metal surface and stabilise ions in solution. However, the presence of ions in solution allows a current to be passed between two electrodes inserted in the solution, and one of these electrodes can be the metal under investigation. This is the field of electrochemistry, and much of our knowledge of the metal–solution interface is derived from electrochemical measurements. Complementary information is gained from many of the techniques used to study the metal–gas interface. The first type of electrochemical system to be considered is one in which the application of a potential across the interface does not lead to charge transfer. Such a system behaves as a capacitance due to the formation of a complex double layer. The effects of various types of adsorption is then described. The deposition of metals on the electrode surface is next considered, and this is followed by a discussion of the reverse metal dissolution reaction. The final section concerns the formation of films on the metal surface, a reaction which has its parallel in metal–gas reactions.     

Selective detection in flow analysis based on the combination of immobilized enzymes and chemically modified electrodes

The combination of immobilized enzymes and amperometry to build selective detection devices in flow-injection analysis and liquid chromatography is described. The pros and cons of enzyme electrodes and of immobilized enzyme reactors are discussed. The paper concentrates on the use of immobilized dehydrogenases, oxidases, peroxidases, and on electrodes on which these enzyme reactions can be selectively followed. The work in the field by the authors is reviewed.     

Toward understanding reactive adsorption of ammonia on Cu-MOF/graphite oxide nanocomposites

The adsorption of ammonia on HKUST-1 (a metal-organic framework, MOF) and HKUST-1/graphite oxide (GO) composites was investigated in two different experimental conditions. From the isotherms, the isosteric heats of adsorption were calculated from the Clausius-Clapeyron equation following the virial approach. The results on HKUST-1 were compared with those obtained using molecular simulation studies. All materials exhibit higher ammonia adsorption capacities than those reported in the literature. The ammonia adsorption on the composites is higher than that measured separately on the MOF component and on GO. The strong adsorption of ammonia caused by chemical interactions on different adsorption sites is evidenced by the trends in the isosteric heats of adsorption. The molecular simulations conducted on HKUST-1 support the trends observed experimentally. In particular, the strong chemisorption of ammonia on the metallic centers of HKUST-1 is confirmed. Nevertheless, higher adsorption capacities are predicted compared with the experimental results. This discrepancy is mainly assigned to the partial collapse of the MOF structure upon exposure to ammonia, which is not accounted for in the simulation study.