二乙腈基二硫纶在金电极上的自组装及其对抗坏血酸的电化学行为研究

将Na2[Ni(mnt)2](mnt=丁二腈烯二硫醇阴离子)自组装到裸金电极表面,制成mnt-SAM/Au修饰电极,并用电化学方法研究了该修饰电极的电化学性质。实验结果表明,mnt-SAM膜对[Fe(CN)6]3-/[Fe(CN)6]4-有一定的排斥作用,而对[Co(phen)3]2+/[Co(phen)3]3+有一定吸引作用。研究了抗坏血酸(AA)在自组装膜修饰金电极上的电化学氧化行为,考察了溶液pH、扫描速率的影响,结果表明该膜对AA的氧化具有催化作用。在最佳条件下,峰电流与AA的浓度在5.0×10-6~1.3×10-3mol·L-1范围内呈良好的线性关系,相关系数为-0.9987,检测限为1.0×10-6 mol·L-1。     

直流电电化学沉积镍制备原位生长碳纳米管化学修饰电极

利用直流电电化学沉积法将生长碳纳米管(CNT)的催化剂镍均匀地附着在石墨电极(GE)表面,再通过化学气相沉积法制备得到原位生长碳纳米管化学修饰电极(GSCNT-CME).电化学沉积的金属镍和所制备的修饰电极分别用光学显微镜、扫描电子显微镜(SEM)和电子能谱(EDX)进行表征,所得修饰电极的电化学性能用[Fe(CN)6]3-/[Fe(CN)6]4-溶液进行表征.结果表明:经直流电电化学沉积,可以在石墨电极表面沉积一层致密的金属镍,能生长出管径均匀的碳纳米管,所制得的修饰电极具有良好的电化学响应灵敏性和准确性,可在电化学检测领域发挥重要的应用.     

钴配合物/单壁碳纳米管修饰电极对尿酸的检测

采用滴加单壁碳纳米管(SWCNTs)悬浮液和电沉积钴配合物[Co(phen)3]2+(phen=邻菲啰啉)的方法,制备了钴配合物-单壁碳纳米管修饰玻碳电极([Co(phen)3]2+-SWCNTs/GCE),研究了尿酸(UA)在该修饰电极上的电化学行为。结果表明,修饰电极对UA具有良好的电催化作用,在1~249μmol·L-1浓度范围内,氧化峰电流与UA浓度之间存在良好的线性关系,检出限(S/N=3)为1μmol·L-1,加标回收率在98%~102%之间。该修饰电极的稳定性和重现性好,可用于UA的定量分析。     

含有二维有序水层的癸二酸锌(Ⅱ)、钴(Ⅱ)超分子配合物的构筑

室温下,在醇水溶液中合成了2个新型配合物,[Zn(phen)3]2·[Zn(C10H16O4)·(H2O)3]·(C10H16O4)2·20H2O(C10H18O4=癸二酸)(1)和[Co(phen)3]2·[Co(H2O)6]·(C10H16O4)3·30H2O(2),并对配合物进行了元素分析分析、红外光谱分析、热重分析以及晶体结构研究.配合物(1)的基本结构单元中含有一个电中性配位单元[Zn(C10H16O4)·(H2O)3]、二个配位阳离子[Zn(phen)3]2+、二个游离的癸二酸根和20个晶格水.Zn原子有两种配位模式,在[Zn(phen)3]2+配位单元中Zn原子与三个邻菲啰啉的六个N原子配位,构成略有畸变的八面体,Zn原子位于八面体的对称中心;在[Zn(C10H16O4)·(H2O)3]配位单元中Zn原子采取五配位的三角双锥构型,两个羧基均采取单齿配位,同一个癸二酸根与相邻的不同Zn原子配位,将相邻的[Zn(C10H16O4)·(H2O)3]配位单元连接起来,自组装得到了无限链状结构.配合物以癸二酸根为模板在ab平面形成了有序水层,该水层由5元,6元水簇,以及其他由羧基参与的各元环组成.与一般常见的6元水簇不同,配合物1中的6元水簇采取了高能量的类似苯环的平面构象.配合物(2)的基本结构单元中含有一个[Co(H2O)6]2+配位阳离子、二个[Co(phen)3]2+配位阳离子、三个游离的癸二酸根和30个晶格水.Co原子也有两种配位模式.在[Co(phen)3]2+配位单元中,Co原子与三个邻菲啰啉的六个N原子配位,构成略有畸变的八面体,Co原子位于八面体的对称中心.在[Co(H2O)6]2+配位单元中Co(II)与6个配位水的氧原子配位,6个配位水中的6个原子和Co(Ⅱ)形成八面体结构.通过水分子之间及水分子和羧基阴离子间的氢键形成了二维有序水层,二维水层中最小的构筑基元为6元环的水,最大的构筑基元为16元环水,每个水环中分别含有6个和16个游离的没有配位的水分子,水分子之间通过很强的氢键作用形成环形的超分子水簇.这些基元片断在二维空间扩展开来,形成二维有序水层.有趣的是,在该水层上通过水分子之间的分子间氢键形成了16元大环水簇,它与两端的六元环共用六条边,每一个16元水环中含有16个游离的没有配位的水分子,水分子之间通过氢键作用形成环形超分子水簇,每个水分子同时作为氢键的给体和受体.[Co(H2O)6]2+和四个羧酸根离子位于十六元环水的中心,与其周围的游离水分子形成了十二个氢键,同时与环外的游离水和羧酸根形成了十个氢键,对大环水聚集体起到稳定作用.     

基于羧基化碳纳米管修饰电极伏安法同时测定痕量锢和铝

基于羧基化多壁碳纳米管(c-MWCNT),制备了可同时测定In3+和Al3+的新型碳材料修饰电极.利用循环伏安法(CV)和交流阻抗法(EIS)对此修饰电极进行了表征,用线性扫描伏安法(LSV)研究了In3+与Al3+共存于修饰电极上的电化学行为.与裸玻碳电极相比,新型碳材料修饰电极的电化学活性得到很大提高;In3+与A...     

碳纳米管尺寸对电化学反应活性的影响

制备不同尺寸的多壁碳纳米管(MWNT)修饰电极,应用循环伏安法研究了相同管径、不同管长和相同管长、不同管径的多壁碳纳米管修饰电极在K3Fe(CN)6溶液中的电化学行为及其对尿酸、多巴胺等生物分子的电催化作用,以及尺寸效应对碳纳米管修饰电极电化学活性的影响规律.结果显示,在同一条件下,短管的MWNT比长管的更能有效促进K3Fe(CN)6的电子传递,更有利于对生物分子的电催化;管径对它的电化学行为及生物电催化活性影响较小,无明显规律.主要原因在于碳纳米管管端、管壁的不同电化学活性.     

[Cu3(μ10-bta)(μ2-C2O4)(H2O)2]n的水热合成与结构表征

有机-无机杂化材料因其在催化、化学吸附、磁性和电子导体等方面具有广泛的应用而成为人们的研究热点[1,2]. 通过过渡金属离子和特殊的有机配体之间的反应, 一系列具有独特结构的配位聚合物已被合成出来. 多齿有机配体可螯合两个或多个金属离子, 这些金属离子之间存在良好的电子交换[3], 可形成一维、二维或三维的配位聚合物. 均苯三甲酸和均苯四甲酸都是良好的桥连多齿配体, Chui等采用均苯三甲酸合成了具有吸附作用的大孔道的[Cu3(tma)2(H2O)]n[4] (tma=benzene-1,3,5-tricarb-oxylate)三维配位聚合物, 并且[Ni(C12H3ON6O2)]3(tma)*H2O[5], [M(tma)2]*12H2O(M=Co,Ni,Zn)[6], Na2[Co(H2O)6(bta)]*4H2O[7] (bta=benzene-1,2,4,5-tetracarboxylate)和[Co(phen)(md)][8] (phen=1,10-phenanthroline, md=benzene-1,3-dicarboxylate)等配位聚合物也先后被合成出来.     

Ru-P/MWCNTs-DHP/GC电极的电化学特性

应用循环伏安法、微分脉冲伏安法、紫外-可见和荧光光谱研究了一种新型钌化卟啉[Ru(phen)2(MPyTMPP)Cl]+(phen=1,10-邻菲咯啉,MPyTMPP=5-(3-吡啶)-10,15,20-三-(4-甲苯基)-卟啉)在多壁碳纳米管(MWCNTs)修饰的玻碳(GC)电极表面的电化学特性及其与电极上和溶液中双十六烷基磷酸盐(DHP)的作用.结果表明:[Ru(phen)2(MPyTMPP)Cl]+能强吸附在MWCNTs-DHP/GC电极表面,并呈现一对由表面过程控制的氧化还原峰;适量DHP有利于该配合物的吸附固定;[Ru(phen)2(MPyTMPP)Cl]+能与溶液中的DHP形成结合体,导致配合物中心离子反应电位负移.     

基于碳纳米管修饰电极的胆碱电化学发光生物传感器研制

在碳纳米管(CNTs)和K3Fe(CN)6修饰的铂电极上吸附固定胆碱氧化酶,以鲁米诺为发光试剂,研制了胆碱电化学发光(ECL)生物传感器.CNTs可有效提高电极表面的电荷传输能力、提高电极表面的生物相容性和对酶分子的固载能力;K3Fe(CN)6对酶活性具有激活作用,同时对H2O2增敏的鲁米诺ECL有增强作用,均有利于提...     

两个3d-4f杂核配合物[Fe(phen)3]2[FeLn(H2O)(tiron)3]·6H2O的合成、晶体结构和磁性(Ln=HoⅢ,YbⅢ)

Ln2O3、硝酸铁、邻菲罗啉和钛铁试剂(tiron)通过水热法自组装合成了2个异质同晶的3d-4f杂核配合物[Fe(phen)3]2[FeLn(H2O)(tiron)3]·6H2O,其中,Ln=HoⅢ(1)和YbⅢ(2)。X-射线单晶衍射分析表明,晶体属立方晶系,P213空间群。3个tiron4-配体利用酚氧桥联Ln3+和Fe3+形成具有C3对称性的[FeLn(H2O)(tiron)3]6-异双核配位单元,其中七配位的Ln3+呈现一种畸变的单帽反三棱柱配位构型。配阳离子[Fe(phen)3]3+通过phen-phen之间的π-π相互作用和与配阴离子间的静电引力等作用组装成三维的超分子。在2～300 K温度范围内测试了配合物的变温磁化率,结果表明,Ln(Ⅲ)-Fe(Ⅲ)之间存在反铁磁性相互作用。     

Electrochemical Behavior of K3[Fe(CN)6] on the Electrode Coated with Modified Multi‐Walled Carbon Nanotubes

The electrochemical behavior of K₃[Fe(CN)₆] was studied on an ITO electrode that was coated with β‐cyclodextrin (CD) modified multi‐walled carbon nanotubes (MWNTs) and with carboxyl modified multi‐walled carbon nanotubes (MWNT‐COOHs). MWNT‐COOHs showed an excellent electrocatalytic effect on the redox of K₃[Fe(CN)₆] while MWNT‐CDs had a subdued effect on the electrochemical response of K₃[Fe(CN)₆]. It is probably due to mismatching between K₃[Fe(CN)₆] and cyclodextrin, which hampers the contact of K₃[Fe(CN)₆] with carbon nanotubes. Moreover, the electrochemical behavior of K₃[Fe(CN)₆] on the MWNT‐COOHs coated ITO electrode at various scan rates also was measured. The results indicated that both potential difference between redox peaks and peak current of K₃[Fe(CN)₆] increased with increasing scan rate. A good linearity of peak current versus scan rate was observed.     

DNA-based biosensor for the detection of strong damage to DNA by the quinazoline derivative as a potential anticancer agent

A disposable electrochemical DNA-based biosensor was developed and applied as a screening device to detect an effect of a synthetically prepared quinazoline derivative on the surface-attached double stranded calf thymus DNA. Screen-printed carbon electrodes without and with multi-walled carbon nanotubes interface served as the signal transducer. The quinazoline interaction with DNA was investigated voltammetrically using DNA-bound electrochemical indicators such as [Co(phen)₃]³⁺, [Ru(bpy)₃]²⁺, methylene blue, the K₃[Fe(CN)₆] complex present in the solution phase as well as by electrochemical impedance spectroscopy. A severe damage to DNA at the incubation of the biosensor in quinazoline solution was found which leads to the loss of DNA from the electrode surface. Agarose gel electrophoresis was used to verify the results.     

Effects of pH on electrocatalytic activity of functionalized carbon nanotubes

In this study, we modified carbon nanotubes (CNTs) by grafting with poly(ethylene glycol) (PEG) using the “grafting to” method. The PEG-grafted CNT (CNT-g-PEG) was cast on indium tin oxide (ITO) electrode to investigate the electrocatalytic activity of CNT to the redox reactions of the Fe(CN)₆^3−/4−as a probe using cyclic voltammetry and electrochemical impedance spectroscopy. The electrocatalytic activity of CNT was correlated with CNT dispersion in the cast film on ITO as a function of pH of aqueous solution from which the film was cast. The CNT dispersions in aqueous solutions of different pH and in the cast films were examined by visual observation and zeta potential, scanning electron microscopy and transmission electron microscopy, respectively. At a pH in the range of 3–11 at which ITO electrode was modified, two functionalized CNT (fCNT and CNT-g-PEG) were both found to electrocatalyze the redox reactions of the Fe(CN)₆^3−/4−probe and the PEG grafts in CNT-g-PEG could help CNT adhere to the electrode to obtain durable modified electrode. The more uniform CNT dispersions in aqueous solutions and in the cast films appeared to have greater electrocatalytic acitivity.     

Sensitively Electrochemical Sensing for Sequence‐Specific Detection of Phosphinothricin Acetyltransferase Gene: Layer‐by‐Layer Films of Poly‐L‐Lysine and Au‐Carbon Nanotube Hybrid

An electrochemical DNA sensing film was constructed based on the multilayers comprising of poly‐L ‐lysine (pLys) and Au‐carbon nanotube (Au‐CNT) hybrid. A precursor film of mercaptopropionic acid (MPA) was firstly self‐assembled on the Au electrode surface. pLys and Au‐CNT hybrid layer‐by‐layer assembly films were fabricated by alternately immersing the MPA‐modified electrode into the pLys solution and Au‐CNT hybrid solution. Cyclic voltammetry was used to monitor the consecutive growth of the multilayer films by utilizing [Fe(CN)₆]^3?/4? and [Co(phen)₃]^3+/2+ as the redox indicators. The outer layer of the multilayer film was the positively charged pLys, on which the DNA probe was easily linked due to the strong electrostatic affinity. The hybridization detection of DNA was accomplished by using methylene blue (MB) as the indicator, which possesses different affinities to dsDNA and ssDNA. Differential pulse voltammetry was employed to record the signal response of MB and determine the amount of the target DNA sequence. The established biosensor has high sensitivity, a relatively wide linear range from 1.0×10^?10 mol/L to 1.0×10^?6 mol/L and the ability to discriminate the fully complementary target DNA from single or double base‐mismatched DNA. The sequence‐specific DNA related to phosphinothricin acetyltransferase gene from the transgenically modified plants was successfully detected.     

Disposable electrochemical biosensor with multiwalled carbon nanotubes-chitosan composite layer for the detection of deep DNA damage.

A novel electrochemical DNA-based biosensor for the detection of deep DNA damage was designed employing the bionanocomposite layer of multiwalled carbon nanotubes (MWNT) in chitosan (CHIT) deposited on a screen printed carbon electrode (SPCE). The biocomponent represented by double-stranded (ds) herring sperm DNA was immobilized on this composite using layer-by-layer coverage to form a robust film. Individual and complex electrode modifiers are characterized by a differential pulse voltammetry (DPV) with the DNA redox marker [Co(phen)(3)](3+), cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS) with [Fe(CN)(6)](3-) as a redox probe in a phosphate buffer solution (PBS). A good correlation between the CV and EIS parameters has been found, thus confirming a strong effect of MWNT on the enhancement of the electroconductivity of the electrode surface and that of CHIT on the MWNT distribution at the electrode surface. Differences between the CV and EIS signals of the electrodes without and with DNA are used to detect deep damage to DNA, advantageously using simple working procedures in the same experiment.     

层层自组装法制备普鲁士蓝修饰电极及对过氧化氢的测定

Fe3+可与电沉积在玻碳电极表面的对氨基苯磺酸发生静电吸附作用并与[Fe(CN)6]4-形成普鲁士蓝(PB),进一步交替重复吸附Fe3+和[Fe(CN)6]4-反应,形成PB晶体.该晶体对还原过氧化氢(H2O2)具有很高的电化学活性.通过循环伏安法、交流阻抗法和计时电流法对传感器进行了电化学表征.研究了该传感器对H2O2的电催化作用,探讨了工作电位,PH值及干扰物质对响应电流的影响.结果表明,在磷酸盐缓冲溶液中(pH =5.4,0.1 mol/L),响应电流与H2O2的浓度在0.97 ～ 32.33 mmol/L范围内具有良好的线性关系,相关系数为0.9993,传感器的响应时间小于5 s,检测限为0.48 mmol/L( S/N为3).     

Preparation of Carbon Nanotubes/Neutral Red Composite Film Modified Electrode and Its Catalysis on Rutin

Neutral red was directly electropolymerized onto the carbon nanotubes modified electrode. A polymerized neutral red/carbon nanotubes composite film was characterized by scanning electron micrograph (SEM) and cyclic voltammetry (CV). Well‐defined voltammetric responses are observed for [Fe(CN)₆]^4?/3? on the composite film modified glassy carbon electrode. And it's found that this modified electrode has good catalysis on the redox of rutin. Differential pulse voltammetry method was used to determinate the concentration of rutin and obtain a linear equation between the current and concentration in a certain range. The modified electrode is satisfied with us for its good sensibility and stability.     

Preparation and characterization on the carbon nanotube chemically modified electrode grown in situ

Carbon nanotube chemically modified electrode (CNT-CME) was prepared by growing carbon nanotube (CNT) in situ on the pretreated graphite electrode (GE) via the catalytic chemical vapor deposition. The pretreated GE was prepared by ultrasonic immersion method using Ni(NO₃)₂ as the catalyst. The CNT growing on the CNT-CME was characterized by transmission electron microscope and scanning electron microscope. The obtained electrode electrochemical performance was characterized by cyclic voltammetry with the Na₂SO₄ solution and [Fe(CN)₆]³⁻/[Fe(CN)₆]⁴⁻ solution. The results showed that the obtained electrode has good current responsive sensitivity and good testing result accuracy, indicating that the obtained electrode may have great application in electrochemical testing field.     

Carbon Nanotube Immobilized Electrode Using Amphiphilic Phospholipid Polymer with Anti‐fouling and Dispersion Property for Electrochemical Analysis

A carbon nanotube (CNT)‐modified electrode was fabricated by dropping a dispersion of multi‐walled CNTs in water‐soluble and amphiphilic phospholipid polymer with both dispersing ability and anti‐biofouling property onto a Au electrode. A poly(2‐methacryloyloxyethyl phosphorylcholine‐co‐n‐butyl methacrylate) (PMB) composed from 50 mol% of 2‐methacryloxylethyl phosphorylcholine and 50 mol% of n‐butyl methacrylate (PMB50) was used as dispersing reagent for CNTs. The dispersion of water‐insoluble material by PMB50 and its antifouling effects in electrochemical analysis were investigated. The CNT‐modified electrode showed an anodic peak potential that was shifted negatively and an increase in the current value for the electrolytic oxidation of nicotinamide adenine dinucleotide. In addition, the charge on PMB50 did not inhibit the electrochemical reaction of the redox compounds K₃[Fe(CN)₆], [Ru(NH₃)₆]Cl₃, and hydroxymethylferrocene. Cyclic voltammetry of K₃[Fe(CN)₆] in 4 % bovine serum albumin (BSA) using a bare Au electrode, the anodic peak current was reduced to 47 % of that without BSA. In contrast, the antifouling effect of the PMB50‐coated electrode meant that the current was only reduced to 70 % of that without BSA.     

气相色谱法研究配位化合物的热稳定性XVIII: 配位CN离子的活化加氢

根据一系列金属(Cr、Mn、Fe、Co、Ni、Cu、Zn、Ag、Sn、La)的六氰合铁(II)、(III)酸盐在H2气分中热分解时所发生的CN^-加氢反应,从晶体结构和电子结构两方面探讨了双金属双端配位对CN^-的活化作用和CN^-的加氢反应机理.研究了CN^-的活化程度与配位金属离子的还原电位及d电子组态之间的关系.