金电极上钴-2,2′-联吡啶的电化学特性及其与生物小分子腺嘌呤的相互作用

近年来，以小分子特别是金属配合物作为探针来研究DNA已引起人们的广泛关注「‘－’j．其中大多使用光谱法，Bard等［‘－’j使用的电化学方法既是一个有效的手段，也是对其它方法的补充［’j．DNA与其它小分子的相互作用有两种方式［’j，一种是外源分子插入DNA分子链的碱基对之间；另一种是外源分子与DNA的核糖一磷酸骨架之间的静电引力作用．为了确认小分子金属配合物与DNA相互作用的方式，我们开展了金属配合物与DNA的重要组成部分碱基的相互作用的研究，以期寻找到金属配合物与DNA作用的确切方式．本文采用金电极研究了钻一2…     

低能氮离子对腺嘌呤水溶液损伤作用的光谱分析

利用气体常压弧光放电产生低能N^ 离子，在阴极位降的加速下被注入到腺嘌呤（A）水溶液中，研究了低能N^ 离子作用后腺嘌呤水溶液的紫外，红外及核磁共振光谱的变化。结果表明，低能N^ 离子的注入对溶液样品造成了多种形式的损伤，其中不仅包括N^ 直接与水作用，还包括溶液中各种碎片之间重新化合，形成丰富多采的损伤产物。     

A New Approach how to Define the Coefficient of Electroactivity of Adenine and Its Twelve Derivatives Using Flow Injection Analysis with Amperometric Detection

We studied the electrochemical behaviour of adenine derivates (adenosine, 2‐aminopurine, 2,6‐diaminopurine, 6‐benzyl‐aminopurine, adenosine monophosphate, cyclic adenosine monophosphate, nicotinamide adenine dinucleotide, adenosine triphosphate, S‐adenosyl‐L ‐methionine, and synthetic derivatives AD‐3, AD‐6 and AD‐9) using flow injection analysis with electrochemical detection using a glassy carbon electrode. The influences of pH, flow rate and potential on the signal height of the studied derivates were tested. The optimal pH was 3, the flow rate of the mobile phase 0.75 mL min^?1 and the potential 1100 mV. Further, we attempted to characterize each of the studied derivatives by mathematical equations and classic analytical parameters. The lowest detection limit was estimated for adenine as 0.9 nM and 2‐aminopurine as 0.5 nM.     

木犀草素与腺嘌呤相互作用的理论研究

本文采用密度泛函理论中的B3LYP方法,在6-31+G~*基组水平上对木犀草素—腺嘌呤复合物进行结构优化和振动频率分析,得到了16种稳定的木犀草素—腺嘌呤复合物.应用分子中的原子理论(AIM)分析、自然键轨道(NBO)理论分析得到复合物氢键性质和特征.通过基组重叠误差(BSSE)校正后的相互作用能、成键临界点电荷密度、二阶稳定化能综合分析,得出三氢键复合物C-11结构是最稳定的.综合比较DNA的四个碱基与木犀草素间的相互作用,木犀草素与胸腺嘧啶的相互作用最强,木犀草素-腺嘌呤相互作用最弱,DNA的四个碱基与木犀草素间的相互作用能均比木犀草素与水间相互作用能大,这说明木犀草素作为抗癌药物能有效的发挥作用.     

An Electrochemical Sensor Based on Gold Nanoparticles Incorporated in Mesoporous MFI Zeolite for Determination of Purine Bases in DNA

An electrochemical sensor was developed based on gold nanoparticles incorporated in mesoporous MFI zeolite for the determination of purine bases. Au nanoparticles (AuNPs) were incorporated into the mesoporous MFI zeolite (AuNPs/m‐MFI) by post‐grafting reaction. The composite materials were characterized by transmission electron microscopy (TEM), X‐ray photoelectron spectroscopy (XPS) and electrochemical methods. Au nanoparticles with a size of 5‐20 nm are uniformly dispersed in the pores of mesoporous MFI zeolite. And the morphology of MFI zeolite can be perfectly kept after pore expansion and Au nanoparticles incorporation. The electrocatalytic oxidation of purine bases (guanine and adenine in DNA) is investigated by cyclic voltammetry (CV) and differential pulse voltammetry (DPV). The surface‐confined Au nanoparticles provide the good catalytic activity for oxidation of purine bases. The simultaneous detection of guanine and adenine can be achieved at AuNPs/m‐MFI composites modified glassy carbon electrode (GCE). The electrochemical sensor based on AuNPs/m‐MFI exhibits wide linear range of 0.5–500 μM and 0.8–500 μM with detection limit of 0.25 and 0.29 μM for guanine and adenine, respectively. Moreover, the electrochemical sensor is applied to evaluation of guanine and adenine in herring sperm DNA samples with satisfactory results.     

腺嘌呤与富马酸共晶体的太赫兹光谱分析

利用太赫兹时域光谱(THz-TDS)技术在室温下对腺嘌呤、富马酸及两者的共晶体进行测量, 实验结果显示腺嘌呤与富马酸共晶体在0.92、1.24、1.52 THz处有明显的吸收峰, 与腺嘌呤和富马酸不同, 表明共晶体物相结构不同于原料. 根据腺嘌呤分子氢键供体与受体的结构特点, 使用密度泛函理论(DFT)对腺嘌呤与富马酸三种可能的共晶体结构进行模拟. 结果显示其中一种可能的共晶体结构在0.89、1.16、1.41 THz处存在特征吸收峰, 与实验结果较好吻合. 由此判断腺嘌呤与富马酸共晶体氢键形成位置为腺嘌呤的氨基与富马酸其中一个羧酸的碳氧双键形成氢键, 而此羧酸的羟基与腺嘌呤六元环上的邻位氮原子形成第二处氢键. 本文还结合理论模拟的结果对腺嘌呤与富马酸共晶体的特征吸收峰对应的相关振动模式进行了归属.     

The molecular orientation of DNA bases on H-passivated Si(1 1 1) surfaces investigated by means of near edge X-ray absorption fine structure spectroscopy

Layers of the DNA bases adenine, cytosine, and guanine were deposited onto hydrogen passivated Si(1 1 1) surfaces. The average tilt angles of these molecules with respect to the substrate surface were determined by the angular dependence of the Near Edge X-ray Absorption Fine Structure (NEXAFS) of the carbon K-edge. The interpretation of the NEXAFS spectra was assisted by a semi-empirical approach to the calculation of the π^∗-transition region which employs density functional theory calculations and core level photoemission data.     

槲皮素与腺嘌呤氢键作用的最佳位点

本文优化得到了16个由槲皮素与腺嘌呤形成的氢键复合物的稳定结构,并计算了它们的结合能.研究发现,在气相和水相中,槲皮素均通过qu1位点与腺嘌呤作用形成稳定的氢键复合物.比较了腺嘌呤与槲皮素形成的氢键复合物、腺嘌呤与胸腺嘧啶形成的Watson-Crick碱基对的相对稳定性.在气相条件下Watson-Crick碱基对更稳定,在水相条件下腺嘌呤与槲皮素形成的氢键复合物更稳定,说明水相条件下腺嘌呤与槲皮素之间的相互作用强于与胸腺嘧啶之间的相互作用.基于标准反应Gibbs自由能变的计算结果估算了水相条件下腺嘌呤与槲皮素形成的氢键复合物和Watson-Crick碱基对的相对平衡浓度.     

Nanomaterial-based electrochemical DNA sensing strategies

DNA sensing strategies have recently been varieted with the number of attempts at the development of different biosensor devices based on nanomaterials, which will further become DNA microchip systems. The investigations at the side of material science in connection with electrochemical biosensors open new directions for detection of specific gene sequences, and nucleic acid-ligand interactions.An overview is reported here about nanomaterial-based electrochemical DNA sensing strategies principally performed for the analysis of specific DNA sequences and the quantification of nucleic acids. Important features of electrochemical DNA sensing strategies, along with new developments based on nanomaterials are described and discussed.     

An investigation of the surface enhanced Raman scattering (SERS) from a new substrate of silver-modified silver electrode by magnetron sputtering

'Pure' silver nanoparticles on silver electrode were prepared by magnetron sputtering. The silver-modified silver electrode has good stability and the silver nanoparticles on silver electrode have homogeneous size distribution. Compared with the silver colloid modified silver electrode, there were no any extraneous component ions on the electrode, for the modified silver nanoparticles are prepared by magnetron sputtering. Synchronously, we obtained much higher quality SERS spectra of adenine molecules on the silver electrode modified by magnetron sputtering (SEMMS), and the study of the adsorption behavior of adenine on the silver-modified silver electrode by surface enhanced Raman scattering (SERS) indicated that the silver-modified silver electrode was highly efficient substrates for SERS investigation. From the rich information on the SEMMS obtained from high-quality potential-dependent SERS, we may deduce the adsorption behavior of adenine and the probable SERS mechanism in the process. The probable reasons are given.