纳米级微带金电极上葡萄糖氧化酶的固定.性质及应用

实现了葡萄糖氧化酶以及葡萄糖氧化酶和电子传递媒体Fe(CN)^3^-~6同时在纳米级微带电极上的固定,用红外光谱和循环伏安对GOD/PPy微电极进行了表征, 研究了微带金电极上聚吡咯恒电位形成过程的动力学及葡萄糖氧化酶对其动力学过程的影响,探讨了微酶电极GOD/Fe(CN)^3^-~6/PPy对葡萄糖氧化的催化作用, 考察了PPy膜厚度和溶液中氧的存在对GOD/Fe(CN)^3^-~6/PPy微电极测定葡萄糖的影响.     

用微芯片化学反应器实现酶催化化学发光测定葡萄糖的研究

葡萄糖是临床化学诊断以及食品分析中重要的检测项目 ,最常用的测定方法是采用葡萄糖氧化酶(GOD)催化葡萄糖与氧分子间反应 ,生成葡萄糖酸和过氧化氢 [1] ,而对过氧化氢的检测则可采用过氧化酶 (POD)催化鲁米诺的化学发光反应进行 [2 ] .FIA对整个过程的实现是十分有效的方式 ,但由于多采用固定化酶反应器 [3～ 5] 使其在制备及分析上较复杂且费用高 .由 Manz等[6] 提出的微型全分析系统(μ- TAS)在针对不同体系的微量分析及在线监测上均具有突出的优越性 .本文使用的含微混合器的微芯片化学反应器采用μ- TAS设计思想 ,建立了化学发…     

生物功能电极I: GOD修饰电极的电化学活性

以二环己基碳化二亚胺为活化剂将葡萄糖氧化酶(GOD)共价键接在玻碳电极上, 伏安实验观察到酶与电极基体的直接电子传递, 有观电子传递速度常数约为1s^-^1, 过程归因于全酶中辅基FAD的氧化还原转变。Ag^+离子的存在强烈地阻碍酶辅基的还原, 这与该离子抑制酶活性的机理可能有联系。Ag^+的抑制作用可由EDTA处理或电化学处理而解除, GOD电极对氧和苯醌的电还原有催化作用。测定了苯醌同还原态GOD的化学反应速度常数, 并讨论用苯醌代替氧作为生物电催化中的电子传递体的优点。     

生物功能电极I: GOD修饰电极的电化学活性

以二环己基碳化二亚胺为活化剂将葡萄糖氧化酶(GOD)共价键接在玻碳电极上, 伏安实验观察到酶与电极基体的直接电子传递, 有观电子传递速度常数约为1s^-^1, 过程归因于全酶中辅基FAD的氧化还原转变。Ag^+离子的存在强烈地阻碍酶辅基的还原, 这与该离子抑制酶活性的机理可能有联系。Ag^+的抑制作用可由EDTA处理或电化学处理而解除, GOD电极对氧和苯醌的电还原有催化作用。测定了苯醌同还原态GOD的化学反应速度常数, 并讨论用苯醌代替氧作为生物电催化中的电子传递体的优点。     

EC-Pt/CNTs葡萄糖氧化酶电极

采用乙基纤维素(EC)和载Pt碳纳米管(CNTs)导电复合材料固定葡萄糖氧化酶(GOD)制备EC-Pt/CNTs葡萄糖氧化酶电极.该电极在0~4 mmol/L的浓度范围内检测葡萄糖,灵敏度为0.85μA/mmol.L-1,浸泡18 d后电极活性仍达80%,EC-Pt/CNTs葡萄糖氧化酶电极可望构建葡萄糖传感器.     

原子力显微镜原位观察球晶界面上片晶的生长

当结晶聚合物由熔融冷却或从浓溶液中析出结晶时 ,在不存在应力和流动的情况下 ,一般形成球晶 .球晶在一定的生长时期内呈现球形外观 ,在偏光显微镜下通常呈现Maltese黑十字消光图样 .球晶作为一种常见的结晶形态 ,由片晶堆积而成[1,2 ] .Keith和Padden认为形成球晶的体系包含杂质和聚合物链 ,由于杂质在片晶生长界面的富集导致片晶产生小角度分叉 ,这样片晶能填满球状的空间[1,2 ] .近年来的研究表明球晶是由一个片晶开始生长 ,片晶在生长过程中不断的诱导成核使片晶分叉 ,首先形成片晶捆束 ,然后片晶向各个方向发散生长 ,最终形成球晶[3…     

传感器与反胶束和酶敏感膜

用传感技术研究了反胶束对酶的构象的影响 .用测定葡萄糖氧化酶 (GOD)酶膜电极响应电流的方法 ,讨论磺基琥珀酸双 2 乙基己基酯钠盐 (AOT)反胶束包埋酶对GOD构象和催化活性的影响 ,GOD/AOT的比值减小而响应电流大大增加 ,意味着大大增加了酶的催化活性和酶构象的稳定性 .     

炭气凝胶纳米颗粒固定葡萄糖氧化酶的直接电化学

利用间苯二酚和甲醛在碱性环境下制备炭气凝胶(CA), 通过扫描电镜(SEM)、透射电镜(TEM)、比表面积测试Brunauer-Emmett-Teller (BET)等方法分析载体的形貌结构; 以CA为载体通过吸附法固定葡萄糖氧化酶(GOD)并修饰玻碳(GC)电极, 得到GOD/CA/GC电极. 在0.1 mol·L^-1磷酸盐缓冲溶液中, 利用循环伏安法研究了GOD/CA/GC 电极的直接电化学行为和对葡萄糖的催化性能. 结果表明, 以CA为载体可以很好地固定GOD并保持其生物活性, 在无任何电子媒介体存在时, GOD在电极上实现了直接电子转移, GOD/CA/GC电极对葡萄糖具有很好的电催化性能.     

孔蛋白-磷脂仿生膜的葡萄糖氧化酶电化学

采用孔蛋白（MspA）和双肉豆蔻磷脂酰胆碱（DMPC）在玻碳（GC）基底表面成功构建有仿生特性的纳米通道膜,同时将葡萄糖氧化酶（GOD）修饰于膜上. 使用循环伏安法研究GOD/MspA-DMPC/GC电极的GOD直接电化学过程以及其对氧气和葡萄糖的响应. 研究发现,MspA与DMPC形成的仿生纳米通道膜内,GOD在接近生物体系FAD/FADH标准电位处实现了自身两质子、两电子表面控制的电化学反应. MspA与DMPC的仿生纳米通道膜体系为GOD提供了理想活性环境.     

纳米金胶增强葡萄糖生物传感器的构建

将纳米金胶(AuNPs)和羟基磷灰石(HAp)按一定比例混合制备了新型复合膜用于葡萄糖氧化酶(GOD)的固定,构建了高灵敏的葡萄糖传感器。由于纳米金胶的存在,葡萄糖氧化酶的直接电化学性质得以增强,在去除氧气的PBS(pH 7.0)介质中,固定在复合膜内的GOD表现出一对良好的氧化还原峰。在饱和氧气条件下,当加入一定量的葡萄糖时,由于GOD催化葡萄糖氧化消耗溶液中的溶解氧,-0.8 V处溶解氧的还原峰电流降低,且峰电流降低的量与葡萄糖浓度在0.02～1.62 mmol/L范围内呈线性相关,检出限为5.0μmol/L,检测灵敏度达9.91 mA.mol-1.L,可实现对葡萄糖的快速检测。     

二氧化碳和丙烯直接合成甲基丙烯酸的NiPMo/TiO2催化剂的研究

用溶胶-凝胶法以磷钼酸(MPA)的镍盐溶液水解钛酸四丁酯制备了NiPMo/TiO2催化剂.使用ICP、 XRD、 TG-DTA、 IR、 TPD-MS和微反应技术研究了催化剂的化学组成、热稳定性、化学吸附性质和催化反应性能.杂多钼酸盐与TiO2通过O2-在TiO2表面发生了键合.在623 K下,杂多阴离子仍保持原有的Keggin结构.CO2在Lewis酸位Ni(Ⅱ)和Lewis碱位Ni-O-Mo的桥氧协同作用下生成CO2卧式吸附态Ni(Ⅱ)←O-(CO)←(O--Ni).丙烯有多种吸附态在催化剂上吸附.在563 K、 1 MPa和空速1500 h-1的反应条件下,丙烯的摩尔转化率为3.2%,产物MAA选择性为95%.     

Toward new camptothecins. Part 6: Synthesis of crucial ketones and their use in Friedländer reaction

In the context of the preparation of camptothecin and luotonin A analogs, the synthesis of some key keto-precursors and their use in Friedländer condensation are described. This paper also focuses on the stability of these keto intermediates and emphasizes the major differences between indolizinones and pyrroloquinazolinones series. Noteworthy is also the report of some original structures isolated as by-products of some experiments.     

CoFe2O4自形成磁性液体场致结构化对磁化的影响

The Langevin paramagnetic theory can’t describe the relation between magnetization of ferrofluids and applied magnetic field. The structuralization of ferrofluids, which is considered the main influence factor of the magnetization, is regarded. The part of magnetization works is deposited when the structure is forming. This action influences the magnetization of ferrofluids directly or indirectly. On the base of the “compressing” model, the Langevin function that usually describes the magnetization of ferrofluid is modified, and a well-fitted curve is obtained. An equation of the relation between the equivalent volume fraction after being “compressed” and the intensity of magnetic field is discovered, which approximately describes the process of magnetization. The relation between the approximate initial susceptibility and the volume fraction can be obtained from modified formula.     

Highly regioselective Buchwald–Hartwig amination at C-2 of 2,4-dichloropyridine enabling a novel approach to 2,4-bisanilinopyridine (BAPyd) libraries

The highly regioselective Buchwald–Hartwig amination at C-2 of the cheap and readily accessible reagent, 2,4-dichloropyridine with a range of anilines and heterocyclic amines is described. This new methodology is robust and provides a facile access to 4-chloro-N-phenylpyridin-2-amines on 0.25 mol scale. These intermediates undergo a further Buchwald–Hartwig amination at higher temperature to enable rapid exploration of the chemical space at C-4 and to provide a library of 2,4-bisaminopyridines.     

KMnO4-mediated oxidative CN bond cleavage of tertiary amines: Synthesis of amides and sulfonamides

KMnO₄-mediated oxidative CN bond cleavage of tertiary amines producing secondary amine was introduced, which was trapped by electrophiles (acyl chloride and sulfonyl chloride) to form amides and sulfonamides. The reaction could take place at mild condition, tolerating a wide range of function groups and affording products in moderate to excellent yields.     

Chemistry of heterocyclic compounds at the A. E. Favorsky Irkutsk Institute of Chemistry, Siberian Branch of the Russian Academy of Sciences, over 50 years (Review)

The review contains a concise historical account and information on the most significant researches undertaken by the staff at the A. E. Favorsky Irkutsk Institute of Chemistry, Siberian Branch of the Russian Academy of Sciences on the Chemistry of Heterocyclic Compounds. Dedicated to Academician of the Russian Academy of Sciences B. A. Trofimov on his 70th jubilee. Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 10, pp. 1443–1502, October, 2008.     

Sulfur-directed metal-free and regiospecific methyl C(sp3)–H imidation of thioanisoles

Regiospecific and direct imidation of the methyl C(sp³)–H bond of thioanisoles is realized under mild and metal-free conditions with N-fluorobis(benzenesulfonyl)imide as an oxidant and nitrogen source. Proposed mechanism suggests that thionium ion intermediates and a Pummerer-type reaction are involved. The imidation has advantages such as high step-economy, excellent functionality tolerance, and regiospecificity, giving structurally diverse imidation products.     

Selective syntheses of 2H-1,3-oxazines and 1H-pyrrol-3(2H)-ones via temperature-dependent Rh(II)-carbenoid-mediated 2H-azirine-ring expansion

The Rh(II)-catalyzed reaction of 2-carbonyl-substituted 2H-azirines with ethyl 2-cyano-2-diazoacetate or 2-diazo-3,3,3-trifluoropropionate provides an easy access to 2H-1,3-oxazines and 1H-pyrrol-3(2H)-ones. These compounds can be selectively prepared from the same starting material using temperature as the only varied parameter. The 2-azabuta-1,3-diene intermediate, a common precursor for both heterocyclic products, isomerizes into 2H-1,3-oxazine under kinetic control, while 1H-pyrrol-3(2H)-one is the sole product of the reaction at elevated temperatures. According to DFT-calculations a one-atom oxazine ring contraction involving ring-opening to a 2-azabuta-1,3-diene intermediate, followed by a 1,5- and 1,2-prototropic shift leads to the consecutive formation of imidoylketene and azomethine ylide, which then further undergo cyclization to the pyrrole derivative.     

Synthesis of 1-benzyloxypyrazin-2(1H)-one derivatives

Different approaches for the synthesis of 1-benzyloxypyrazin-2(1H)-one derivatives from simple amino acids have been investigated. A library of 33 precursors for the preparation of N-hydroxy pyrazinones was obtained in moderate to good yields.