细胞色素C在单糖修饰金电极上的直接电化学

Hill等发现在4,4′-联吡啶存在时,细胞色素C在金电极上能进行准可逆的电化学反应。在研究细胞色素C的直接电化学过程中,人们又发现一些生物小分子如氨基酸、嘌呤等对细胞色素C的电化学反应有促进作用,但迄今未见有关糖类分子对细胞色素C电化学反应促进作用研究的报道。本文研究了5种单糖对细胞色素C电化学反应的促进作用。     

细胞色素C在糖及醇修饰金电极上的直接电化学

细胞色素C在生物体内能进行可逆的氧化还原反应，但它知不能直接在金属电极上进行可逆的电化学反应．因此在早期细胞色素（：的电化学研究中，人们往往借助干一类称为媒介体山的分子，这给细胞色素C的电化学反应研究带来很大的不便．IO77年，hill等人间发现在4／一联毗陡存在下     

细胞色素C电化学反应的静电作用模型

首次发现,简单的阴离子Ⅰ~-是细胞色素c电化学反应的良好促进剂。在碘离子修饰的金电极上能观察到细胞色素c的准可逆电化学反应。根据细胞色素c的结构特点和碘离子的吸附特性,提出了一个以静电作用为基础的细胞色素c的电化学反应的模型。     

聚双吡啶中残留单体的薄层色谱定量分析

双吡啶化合物是一类具有可逆氧化还原功能的化合物群。它们的高分子衍生物在光能转换、电色显示及氧化还原催化剂等领域,有着广泛的用途。由4,4′-双吡啶(BPY)和对二氯二甲苯(p-DCX)通过逐步四级化反应合成的聚双吡     

细胞色素c在2-巯基嘧啶衍生物修饰金电极上的直接电化学

用循环伏安法研究了2-巯基嘧啶(MP)、4-氨基-2-巯基嘧啶(AMP)及4,6-二氨基-2-巯基嘧啶(DAMP)自组装修饰金电极的制备及其对细胞色素c直接电子传递的促进作用。用扫描电子显微镜(SEM)表征了2-巯基嘧啶衍生物修饰金电极的表面形貌。细胞色素c在MP、AMP修饰金电极上能进行准可逆的电化学反应,氧化还原峰电位差(ΔEp)分别为61 mV和86 mV,氧化与还原峰电流比ipa/ipc接近1,峰电流与电位扫描速率平方根(v1/2)呈正比,是扩散控制的准可逆过程,异相电子迁移速率常数(Ks)分别为1.4×10-3cm·s-1和5.1×10-5cm·s-1。金电极在2.0 mmol·L-1MP、AMP溶液中分别浸泡3 h和9 h,促进效果较好。随2-巯基嘧啶环上取代氨基数的增加,对细胞色素c电化学反应的促进作用及电极的稳定性逐渐减弱,即MP>AMP,而DAMP基本无促进作用。     

细胞色素c在微带金电极上的直接电化学

报道了一种新的促进剂4,6-二甲基-2-巯基嘧啶(DMMP)对细胞色素c(Cyt.c) 电化反应的促进作用,用红外光谱和光电子能对DMMP 在金电极表面形成的单分子膜进行了表征.循环伏安实验表明Cyt.c在DMMP修饰微电极上能发生准可逆的电化学反应,异相电子传递速率常数K~5为6.6×10^-^3cm/s,对DMMP修饰膜的稳定性进行了考察;讨论了Cyt.c发生电化学反应的异相电子传递速率常数K~5受电极, 表面促进剂的修饰量以及空气中氧影响的机理.     

细胞色素C的薄层光谱电化学研究

细胞色素C(Cyt. C)在电极界面上的电子传递十分缓慢,只有在适当的电子迁移中介体(Mediator)或促进剂(Promoter)参与下才能以较快的速度进行反应,本文报道了以4,4′-二硫基联吡啶(PySSPy)作电极反应促进剂,用薄层光谱电化学技术研究细胞色素C在金微网栅薄层透光电极界面上的电化学过程,测定了电极反应的热力学参数E~(o′)及n,并与循环伏     

固相研磨合成4,4′-联吡啶季铵盐

采用室温固相研磨的方法,4,4′-联吡啶与连有阻塞基的乙氧乙醇磺酸酯(或苄溴)反应,得到单取代的4,4′-联吡啶六氟磷酸盐(2),2再与α,α′-二(溴甲基)-2,2′-联吡啶反应,得到哑铃型化合物——2,2′-联吡啶桥连的双-4,4′-联吡啶六氟磷酸盐(3),收率约90%。2和3的结构经1HNMR,13CNMR和MS表征。     

二维配位聚合物[Cu(μ-I)(μ-4,4-bipy)]_n的溶液合成与晶体结构(英文)

碘化亚铜和4,4′-二联吡啶在溶液中反应的二种方法可制备出标题化合物的2个不同红色晶体,结构表征出两种晶体分别是单斜C2/c(1)和四方I41/acd(2)空间群。在[Cu(μ-I)(μ-4,4-bipy)]n结构中,铜原子是处于与2个碘原子和2个相互扭曲4,4′-二联吡啶中的氮原子的扭曲四面体配位环境中,2个[Cu(μ-I)]2单元和2个桥式4,4′-二联吡啶配体形成1个[Cu2(μ-I)2(μ-4,4-bipy)]2直角单元,4个直角单元经4个4,4′-二联吡啶侧式桥联而形成1个大的八角环,并由此与直角单元相互垂直而形成1个二维框架结构。     

细胞色素c在羟基磷灰石修饰玻碳电极上的直接电化学

采用沉淀法合成羟基磷灰石纳米晶体，由于具有独特的多吸附位点特征，羟基磷灰石可作为一种新型电子传递促进剂用于细胞色素c的直接电化学研究．在pH7．0的磷酸盐缓冲溶液中，细胞色素c在羟基磷灰石修饰玻碳电极表面于0．074V(vs．Ag/AgC1)处有一对准可逆的氧化还原峰，为细胞色素c血红素辅基Fe(Ⅲ)／Fe(Ⅱ)电对的特征峰．实验结果表明细胞色素c与羟基磷灰石之间的静电作用．促进了细胞色素c在玻碳电极表面扩散控制的准可逆单电子转移过程．讨论了电位扫描速度、溶液离子强度对细胞色素c直接电化学的影响．     

液体弹珠：制备策略、物理性质及应用探索

Liquid marbles (LMs) are liquid droplets coated with a layer of lyophobic particles at the air-liquid interface. Since the pioneering work by Aussillous et al. in 2001, LMs have attracted significant attention owing to their facile fabrication, flexibility in the choice of the constituent particles and liquids, intriguing properties such as non-wetting and non-adhesive nature, satisfactory elasticity and stability, as well as promising applications in microfluidics, sensors, controlled release, and microreactors. The classical strategy for the preparation of LMs involves rolling a small volume of a droplet on a lyophobic powder bed for complete encapsulation of the liquid by the particles. In addition, various innovative methods, including electrostatic and coalescent approaches, have been developed for preparing special LMs with a complicated structure or morphology. Diverse materials such as water, surfactant solutions, liquid metals, reagents, blood, and even viscous adhesives have been employed as the internal liquid for the fabrication of LMs. Theoretically, any particulates such as lycopodium, polytetrafluoroethylene, Fe₃O₄, SiO₂, and graphite grains can be employed as the outer coating, but they are usually required to be lyophobic with sizes of less than hundreds of microns. The unique structure of the particle-covered droplet and the dual solid-liquid characteristics endow LMs with some unique and interesting properties, especially the non-wetting and non-adhesive nature. As the lyophobic coating particles restrain the internal liquid from contacting the substrate, LMs can move easily across either solid or liquid surfaces, neither wetting the substrate nor contaminating the internal liquid. An equally fascinating property of LMs is their satisfactory stability, which is necessary for most of their applications. The high stability of LMs stems from the protection of the coating powders and is embodied in both good mechanical stability (remaining intact after being released from a certain height or under a certain compression) and long lifetime (greatly suppressing the evaporation of the internal liquid). These extraordinary properties make LMs promising candidates for use in multitudinous fields, especially droplet microfluidics and microreactors. The potential application of LMs in microfluidics is ascribed to their non-wetting, non-adhesive nature and other features such as an ability to float on a liquid surface, coalescence, split, a small force of rolling friction, and response to external forces. Notably, LMs hold great promise for applications in microreactions, because they can create a confined reaction microenvironment, minimize reagent usage, facilitate unhindered gas exchange between the internal liquid medium and the surrounding environment, and allow the entry/exit of the reactants/products. We herein review the recent advances in LMs, such as manufacturing techniques, formation mechanisms, physical properties, and emerging applications. In particular, much attention is paid to the factors affecting the stability of LMs and the potential strategies to increase their stability. Moreover, this review discusses the challenges in the future development of LMs, suggests several possible ways of addressing these challenges, and forecasts the future development directions. We believe that this review can help researchers gain a better understanding of LMs and promote their further advances.     

磁性离子印迹技术用于元素形态分离分析

元素的形态决定了其在环境和生物过程中的不同行为,形态分析正在被分析化学、环境化学、地球化学、生态学、农学和生物医学等众多学科所关注。环境和生物样品基质复杂、化学形态多样、含量低且易转化是元素形态分析面临的挑战,因此对元素形态的甄别、定量、生态毒性评价和生理功能研究需要对原生形态进行高选择性识别和高效率分离。固相萃取是一种有效应对以上难题的方法,但现有材料和方法远不能满足要求。离子印迹聚合物可与印迹金属离子特异性结合,具有准确、灵敏、可靠的特点,近年来在元素形态分离富集和分析检测方面得到了较为广泛的应用。鉴于非磁性吸附剂在固相萃取操作时,需要将分散在样品溶液中的吸附材料经过离心或过滤分离,操作比较繁琐费时,而磁性材料易被外部磁场快速分离,因此操作简便快速的磁固相萃取正成为元素形态分离富集中一种极具潜力的方法。这篇综述系统总结了离子印迹技术的最新进展,包括离子印迹技术的原理、离子印迹聚合物的制备方法,并根据元素形态分析中离子印迹磁固相萃取的发展现状,分析了离子印迹技术所面临的挑战,最后对元素形态分析中离子印迹技术的未来发展方向和策略提出了建议,提出开发基于有机-无机杂化聚合的多功能磁性离子印迹纳米复合物用于样品的前处理是建立识别选择性高、分离能力强、吸附容量大、形态稳定性好的形态分析方法的一种重要举措。     

The Oxidation of Guaiacol,Serotonin, o-Cresol,p-Cresol,m-Cresol,Homovanillic Acid,and m-Tyrosine by Horseradish Peroxidase and Hydrogen Peroxide

Abstract

A survey of 14 substrates for the fluorometric determination of the oxidative enzyme-horseradish peroxidase was carried out. The compounds which seemed to act well as substrates are serotonin, guaiacol, o-cresol, p-cresol, m-cresol, homovanillic acid and m-tyrosine. L-Epinephrine, equilenin, equilin, β-estradiol, estriol, and estrone were studied and found not to be substrates of the system.

The kinetics of the oxidation reactions were studied. They followed the Michaelis constant rate equation. The Michaelis constant, Km, was determined by a Lineweaver-Burk plot for each substrate.

It would appear that the presence of a group in the ortho, para, or meta position of the phenolic ring decreases the binding of the subtrate to the enzyme's active site, as shown by the km values obtained. It may be concluded that m-tyrosine is the best substrate (lowest km value) when compared to all the substrates which have been studied to date by the authors.     

ICP–AES法测定稀土硅铁球化剂和孕育剂中钙、镁、铝、锰、镧、铈

建立了电感耦合等离子体原子发射光谱法(ICP–AES)测定稀土硅铁球化剂和孕育剂中Ca,Mg,Al,Mn,La,Ce等元素含量的方法。通过基体匹配消除了铁基体的干扰,Ca,Mg,Al,Mn,La,Ce的分析谱线分别为317.933,279.553,394.401,257.610,333.749,456.236 nm。各元素标准曲线的线性相关系数均在0.999以上,检出限在0.000 1%~0.000 4%之间。方法的加标回收率为99.4%~102.8%,测定结果的相对标准偏差均小于3%(n=11)。用该方法测定标准样品,测定结果与认证值相吻合。该法适用于稀土硅铁球化剂和孕育剂中钙、镁、铝、锰、镧、铈的测定。     

甘油催化氢解制备精细化学品的研究进展

随着生物柴油产业的快速发展,作为副产物的甘油大量过剩,因而有效利用甘油既能促进生物柴油产业的良性发展,又能节约大量石油资源。通过甘油催化氢解的方式来制备高附加值化学品丙二醇、乙二醇和丙醇等是甘油转化研究中最有潜在应用价值的路径之一,甘油氢解反应易于实现连续化生产,且目标产物附加值高、选择性高,因而具有良好的经济效益。本文首先简要介绍了甘油化学,深入探讨了甘油的氢解机理,然后重点综述了甘油氢解制备1, 2-丙二醇、1, 3-丙二醇、乙二醇和丙醇高效催化剂的研究进展,并对甘油氢解未来的研究方向和发展趋势作了进一步展望。     

电感耦合等离子体光谱法(ICP-AES)测定银精矿中铜、铅、锌、砷、镉、钙、镁、锰含量

针对银精矿样品复杂,难消解的特点,研究了不同酸溶法和碱熔法对样品的消解情况,建立了硝酸,盐酸,氢氟酸,高氯酸消解银精矿的方法。根据元素灵敏度和抗干扰性,选定各元素的测定波长。通过酸溶样和碱熔样测定结果比对,验证了方法准确性。建立了四酸消解-电感耦合等离子体光谱法测定银精矿中铜、铅、锌、砷、镉、钙、镁、锰含量的方法,元素的线性相关系数均在0.9999以上。通过共存元素干扰实验,确定了银精矿中高含量元素(铜、铅、锌、铁、锑、铋等)对测定元素结果没有影响。方法检出限：Cu 0.0063 mg/L, Pb 0.0159 mg/L ,Zn 0.0090 mg/L,As 0.0192 mg/L, Cd 0.0093 mg/L ,Ca 0.0084 mg/L, Mg 0.0075 mg/L, Mn 0.0081 mg/L。测定下限：Cu 0.0105mg/L,Pb 0.0265 mg/L, Zn 0.0150 mg/L, As 0.0320 mg/L, Cd 0.0155 mg/L, Ca 0.0140 mg/L, Mg 0.0125 mg/L,Mn 0.0135 mg/L。3个样品的相对标准偏差在0.87%~3.56%之间,加标回收率在95.00%~103.56%之间。方法流程短,操作简单,快速,灵敏度和再现性高,结果准确可靠,可以满足银精矿中铜、铅、锌、砷、镉、钙、镁、锰含量的测定。     

Polysaccharide-Based Drug Delivery Systems for the Treatment of Periodontitis

Periodontal diseases are worldwide health problems that negatively affect the lifestyle of many people. The long-term effect of the classical treatments, including the mechanical removal of bacterial plaque, is not effective enough, causing the scientific world to find other alternatives. Polymer–drug systems, which have different forms of presentation, chosen depending on the nature of the disease, the mode of administration, the type of polymer used, etc., have become very promising. Hydrogels, for example (in the form of films, micro-/nanoparticles, implants, inserts, etc.), contain the drug included, encapsulated, or adsorbed on the surface. Biologically active compounds can also be associated directly with the polymer chains by covalent or ionic binding (polymer–drug conjugates). Not just any polymer can be used as a support for drug combination due to the constraints imposed by the fact that the system works inside the body. Biopolymers, especially polysaccharides and their derivatives and to a lesser extent proteins, are preferred for this purpose. This paper aims to review in detail the biopolymer–drug systems that have emerged in the last decade as alternatives to the classical treatment of periodontal disease.     

石墨烯纤维：制备、性能与应用

石墨烯纤维是一种由石墨烯片层紧密有序排列而成的一维宏观组装材料。通过合理的结构设计和可控制备,石墨烯纤维能够将石墨烯在微观尺度的优异性能有效传递至宏观尺度,展现出优异的力学、电学、热学等性能,从而应用于功能织物、传感、能源等领域。目前,石墨烯纤维主要通过湿法纺丝、限域水热组装等方法制备得到,其性能可以通过对材料体系和制备工艺的优化而进一步提升。本文首先介绍了石墨烯纤维的制备方法,然后详细阐述了石墨烯纤维的性能,讨论了其性能提升策略,并总结了石墨烯纤维的应用,最后对石墨烯纤维的未来发展、挑战和前景进行了展望。     

半导体光催化研究进展与展望

评述了目前半导体光催化在国内外的研究概况,并对存在的问题和未来的发展动向进行简要分析.列举了近30年来关于光催化研究的部分成果,内容涉及光催化剂的制备(包括新催化剂的开发, TiO2、 ZnO、 CdS等光催化剂的各种改性或修饰)、光催化作用机理研究、光催化技术的工程化、光催化技术的各种应用研究和产品开发等等从基础到应用研究的各个方面.总体上来看,半导体光催化基本上是一个没有选择性的化学过程,所以再进行大量的不同反应物的光催化活性的评价研究意义已不是很显著,认为未来的半导体光催化研究应该集中在机理的深刻认识、光响应范围宽和量子效率高的催化剂制备、半导体光催化技术工程化及新型光催化产品开发方面.     

Novel High-Performance Ceramics—Amorphous Inorganic Networks from Molecular Precursors

Materials research is an interdisciplinary field in which engineers and physical scientists work together. Since the major binary oxides, nitrides, and carbides, which are currently used as high-performance ceramics, were discovered in the last century, the role of chemistry in the development of materials has become barely noticeable. This has changed only in the recent past as, for example, purity and defined morphology of starting powders were recognized as crucial parameters for enhancing the reliability of ceramic workpieces. While the application of chemical methods led to gradual–though significant–improvements, the true potential of chemistry lies rather in the exploitation of new chemical systems and the development of new preparative routes to already known materials. Such an approach is the preparation of ceramics from molecular or polymeric precursors. Herein we survey the most important contributions to those preparative routes starting from the pioneering work in the 1960s and the 1970s; a certain emphasis is placed on the concepts that we have applied to the preparation of multinary, nonoxide materials and amorphous inorganic networks. The name “amorphous high-performance ceramics” is in fact a contradiction in terms. Such materials are thermodynamically unstable with respect to the transformation or decomposition to crystalline phases, thus excluding their application in sensitive areas at high temperatures. However, the selection of element combinations for which the binding energies are derived from strong, local covalent bonds and which are therefore less dependent on a long-range crystalline order, can yield amorphous materials of remarkable thermal and mechanical durability. This is exemplified by novel quaternary ceramics in the Si/B/N/C system, for which an efficient synthesis, starting from raw materials suitable for industrial production, has been developed. For instance, a material of the composition SiBN₃C remains amorphous up to 1900°C, which is unique, and, with respect to oxidation, is the most stable nonoxide ceramic known to date. Another advantage of this in several respects unsurpassed material is the simple way, in which the viscosity of the polymeric precursors can be adjusted to various methods of shaping. So far infiltrations and coatings have been realized. Most developed is the preparation of fibers, which in terms of their performance characteristics are significantly better than those currently available.