Renewable amperometric immunosensor for complement 3 assay based on the sol-gel technique

A renewable amperometric immunosensor based on the sol-gel technique has been constructed by dispersing graphite, complement 3 (C3) antiserum, and sol-gel at low temperature. The prepared immunosensor is rigid, porous, and has a renewable external surface. A competitive binding assay has been used to determine C3 in human serum with the aid of C3 labeled with horseradish peroxidase. The enzyme-labeled antigen can readily diffuse toward the encapsulated antibody, which retains its binding properties. The experimental conditions for the assay with the biocomposite, including the loading of C3 antiserum in the biocomposite, the amount of labeled C3 in incubation solution, incubation time, and temperature, have been optimized. Using C3 labeled with horseradish peroxidase, and o-AP as the substrate, amperometric detection at -150 mV (relative to the SCE) results in a linear detection range of 1.17-35.1 microg mL(-1), with a detection limit of 0.56 microg mL(-1). Serum samples have been assayed and the results demonstrate the feasibility of the proposed immunosensor for clinical analysis. The surface of the immunosensor can be renewed simply by polishing to obtain a fresh immunocomposite ready to use in a new competitive assay.     

Kinetic isotope effects implicate the iron-oxene as the sole oxidant in P450-catalyzed N-dealkylation

Multiple oxidants have been implicated as playing a role in cytochrome P450-mediated oxidations. Herein, we report results on N-dealkylation, one of the most facile reactions mediated by P450 enzymes. We have employed the N-oxides of a series of para-substituted 13C2H2-labeled N,N-dimethylanilines to function as both substrates and surrogate oxygen atom donors for P450cam and P4502E1. Kinetic isotope effect profiles obtained using the N-oxide system were found to closely match the profiles produced using the complete NAD(P)H/NAD(P)-P450 reductase/O2 system. The results are consistent with oxidation occurring solely through an iron-oxene species.     

UO22＋•nH2O和PuO22＋•nH2O (n＝2, 4, 5, 6)密度泛函理论研究

首先用密度泛函理论(DFT)方法研究了铀酰和钚酰离子的几何与电子结构, 计算结果与实验基本符合, 表明DFT方法也能用于含铀和钚重原子的化合物计算. 然后对铀酰和钚酰水合离子的几何构型、Mulliken集居数分布以及铀酰(钚酰)与配体水分子的结合能进行计算, 计算结果表明UO₂^2＋•5H₂O和PuO₂^2＋•5H₂O分别为铀酰和钚酰系列水合离子中最稳定的配合物.     

Nucleophilic Addition of CH, NH, and OH Bonds to the Phosphadiazonium Cation and Interpretation of (31)P Chemical Shifts at Dicoordinate Phosphorus Centers

The phosphadiazonium cation [MesNP](+) reacts quantitatively with the fluorenylide anion, MesNH(2), and MesOH (Mes = 2,4,6-tri-tert-butylphenyl), resulting in formal insertion of the N-P moiety into the H-Y (Y = C, N, O) bonds. Specifically, reaction of MesNPCl with fluorenyllithium gives the aminofluorenylidenephosphine [crystal data: C(31)H(38)NP, monoclinic, P2(1)/c, a = 9.568(8) ?, b = 24.25(2) ?, c = 11.77(1) ?, beta = 101.38(8) degrees, Z = 4]. Similarly, reaction of [MesNP][GaCl(4)] with MesNH(2) gives the diaminophosphenium salt [MesN(H)PN(H)Mes][GaCl(4)] [crystal data: C(36)H(60)Cl(4)GaN(2)P, monoclinic, C2/c, a = 24.921(2) ?, b = 10.198(4) ?, c = 16.445(2) ?, beta = 93.32(1) degrees, Z = 4], and reaction with MesOH gives the first example of an aminooxyphosphenium salt [MesN(H)POMes][GaCl(4)]. It is proposed that the reactions involve nucleophilic attack at phosphorus followed by a 1,3-hydrogen migration from Y to N. Experimental evidence for the formation of sigma-complex intermediates is provided by the isolation of [MesNP-PPh(3)][SO(3)CF(3)] [crystal data: C(37)H(44)F(3)NO(3)P(2)S, triclinic, P&onemacr;, a = 10.663(1) ?, b = 19.439(1) ?, c = 10.502(1) ?, alpha = 103.100(7) degrees, beta = 113.311(7) degrees, gamma = 93.401(7) degrees, Z = 2]. As part of the unequivocal characterization of the aminooxyphosphenium salt, detailed solid-state (31)P NMR studies and GIAO calculations on the phosphenium cations have been performed. Contrary to popular belief, the phosphorus shielding in dicoordinate cations is not caused by the positive charge but results from efficient mixing between the phosphorus lone pair and pi orbitals.     

Absorptiometric determination of sulphide ion

An absorptiometric method is described for sulphide ion, based on the green colour which is formed when sulphide ions are treated in ammoniacal solution with iron(III) and an excess of nitrilotriacetic acid. The recommended procedure can be applied from 1200 down to 8 ppm of sulphide and is interfered with seriously only by selenite from amongst seventeen other anions examined. The colour system is stabilized by an excess of sulphite. Suggestions are made about the nature of the colour body and its mechanism of production.     

方酸染料在远红光区／近红外区对纳米晶二氧化钛电极的高效敏化作用

Four para-dialkylaminophenyl （PDAAP1-PDAAP4） bearing carboxyl groups were studied for application to the dye-sensitized solar cells （DSC）. It was found the short spacer CH2 between carboxyl and dialkylaminophenyl chromophore in PDAAP3 and PDAAP4 led to highly efficient monochromatic incident photon-to-current conversion efficiencies （IPCE）, however the long alkyl group C4H9 attached on aniline moieties in PDAAP2 and PDAAP4 favored improvement of open-circuit photovoltage. Thus, the solar cell sensitized by PDAAP4, having both short carboxyl groups CH2COOH and long alkyl groups C4H9, exhibited the IPCE maximum of 73% at 670 nm and overall energy conversion efficiency η of 3.06%, representing the highest IPCE and η values so far in dialkylaminophenyl-based organic dye-sensitized semiconductor solar cells. Taking advantage of the highly efficient sensitizing ability of PDAAP4 in far-red region, the data of IPCE above 630 nm of the solar cells were improved greatly by cosensitization with both N3 and PDAAP4. The influences of the TiO2 film thickness and the concentration of 4-tert-butylpyridine （TBP） in electrolyte were also investigated.     

3-氨基环己基甲酸和cis-3-氨基环己烯基-5-甲酸立体异构体的合成

通过手性胺拆分方法，从3-环己烯基甲酸出发分别合成得到了3-氨基环己基甲酸（ACHC）的四个立体异构体，以及cis-5-氨基-3-环己烯基甲酸（ACHEC）的二个立体异构体。     

催化光度法测定痕量钼—钼（Ⅵ）—盐酸联氨—橙黄Ⅳ催化光度新体系

基于盐酸介质中，钼（Ⅵ）催化盐酸联氨还原橙黄Ⅳ的反应，建立了动力学分光光度法测定痕量钼的新方法。本法检出限为３．７×１０＾－３μｇ／ｍＬ，测定钼量范围为０．０２５～１．８μｇ／ｍＬ。已将此法用于测定绿豆中的钼及钼酸铅和钼酸钡的溶度积。     

铁氰化锰修饰玻碳电极的制备及其电化学性能

A thin film of manganese hexacyanoferrate （MnHCF） was electrochemically formed on a glassy carbon （GC） electrode to prepare a chemically modified electrode （CME）. The mechanism of film formation of MnHCF and its growth process were investigated in detail by cyclic voltammetry. The results show that the stoichiometric composition of MnHCF is Mn^ⅢFe^Ⅲ（CN）6, an analogue of prussian yellow. There exist three clear-cut stages in the whole modification process and the last stage is indispensable to the fabrication of homogenized, stable MnHCF film and must last for an appropriate time. The surface morphology of MnHCF/GC electrode was characterized by scanning electron microscopy （SEM）, which further verified the effective deposition of MnHCF film on GC. The kinetic constants of MnHCF/GC electrode process were also evaluated. The resulting MnHCF film modified electrode presented good stability and high electrocatalytic activity toward the oxidation of H2O2, indicating that MnHCF film possesses function of catalase and can be expected for analytical purposes.