Discriminating between Parallel,Anti-Parallel and Hybrid G-Quadruplexes: Mechanistic Details on Their Binding to Small Molecules

G-quadruplexes (G4) are now extensively recognised as a peculiar non-canonical DNA geometry that plays a prime importance role in processes of biological relevance whose number is increasing continuously. The same is true for the less-studied RNA G4 counterpart. G4s are stable structures; however, their geometrical parameters may be finely tuned not only by the presence of particular sequences of nucleotides but also by the salt content of the medium or by a small molecule that may act as a peculiar topology inducer. As far as the interest in G4s increases and our knowledge of these species deepens, researchers do not only verify the G4s binding by small molecules and the subsequent G4 stabilisation. The most innovative studies now aim to elucidate the mechanistic details of the interaction and the ability of a target species (drug) to bind only to a peculiar G4 geometry. In this focused review, we survey the advances in the studies of the binding of small molecules of medical interest to G4s, with particular attention to the ability of these species to bind differently (intercalation, lateral binding or sitting atop) to different G4 topologies (parallel, anti-parallel or hybrid structures). Some species, given the very high affinity with some peculiar G4 topology, can first bind to a less favourable geometry and then induce its conversion. This aspect is also considered.     

Array of MIP-Based Sensor for Fruit Maturity Assessment

Traditionally, fruits are harvested through conventional methods which are based on smell, texture and harvesting time. This analytical technique has many disadvantages in terms of objectivity and subjectivity. By determining various fruits volatile released during pre-matured until matured period, one can actually selectively establish the exact time of a fruit to ripe. The aromatic volatile compounds emitted by Harumanis mango were analyzed using GCMS and found that terpenes hydrocarbon e.g. limonene, α-pinene, β-pinene, α-terpinene, γ-terpinene and 3-carene are the major volatiles that released by the ripe mango. In this work, MIP (Molecularly Imprint Polymer) based sensor array were fabricated and tuned to mango aroma volatiles. HyperChem software simulation is used to obtain key information such as the Binding Energy (ΔE) between the template and the functional monomer that lead to the stable MIP. Designing the MIP using HyperChem is an advantage into saving time and cost compare to trial and error experimental methods. Array of different MIPs template e.g. limonene, α-pinene and β-pinene were synthesis and coated onto the surface of QCMs (Quartz Crystal Microbalance) followed by polymerization and removal of templates molecules that will leave the cavity of selective templates. These QCM arrays are able to distinguish between different terpenes gases released by maturity and ripeness mango due to its selectivity and sensitivity properties of sensor response. The findings of this study is a great breakthrough for the agricultural sector as volatile sensing of chemical markers could determine the optimal harvest time of the local fruits and ensuring the quality and standards.     

新型微梁阵列生化传感器的研制

为了消除单微梁生化传感系统中存在的温度漂移、溶液折射率变化等环境噪声影响,同时实现多种靶标分子的快速并行检测,设计制作了新型微梁阵列生化传感器.利用压电驱动激光束扫描微梁阵列,并通过光杠杆法实时读出微梁弯曲信号,即可得到在微梁表面发生的特异性生化反应的动力学曲线.对250 μm间距的两定点的9h扫描实验数据验证了系统光路的稳定性;同时进行了温度激励测试,升温6℃后微梁阵列弯曲信号基本保持一致(误差6.5％),验证了系统检测的可靠性.最后,利用自制毛细管阵列套合修饰装置,成功将克伦特罗抗体修饰到微梁阵列一侧的金表面上,对待测液中10μg/L克伦特罗标样进行了准确检测,验证了此传感系统在生化检测中的实际可行性.     

基于新型可视化学传感阵列的氨基酸快速识别

以卟啉和其衍生物及指示剂为传感元件,构建了一种对氨基酸敏感的可视传感阵列.可视化学传感阵列以交互响应的敏感元件组成阵列,对不同物质产生特异的响应,并通过信号识别处理系统,将检测结果以图谱的方式显示,实现检测的可视化.研究中筛选了对氨基酸敏感的36种化学物质,构建了6×6的传感阵列,使用自主研发的阵列数据采集与处理系统,对10种具有代表性的常见氨基酸进行了检测,氨基酸溶液与阵列的反应时间为5 min.对实验检测结果数据采用主成分分析和判别分析进行了计算和分析.实验结果显示,通过阵列响应的可视差图可以将浓度为375 μmol/L的10种氨基酸明显区分.判别分析结果显示,本可视阵列对氨基酸识别的准确率达到97%.二维主成分散点图和判别分析散点图对10种氨基酸都有显著分辨效果.本可视传感阵列可用于氨基酸的快速识别.     

主-客体化学研究进展

以分子识别为基础的主－客体化学作为新兴交叉学科，已成为当今研究的热点。本文概述了主体分子的类型、结构特征、分子识别特性及其在某些领域的应用。参考文献56篇。     

可视交叉传感阵列对蛋白质及其热变性过程的快速识别

以卟啉及其衍生物和特异性染料为敏感化学元件, 基于交叉响应原理构建了识别蛋白质的可视6×6阵列. 该阵列以颜色差谱图显示其与蛋白质作用呈现的特异性光谱反应, 采用聚类分析、 主成分分析和欧氏距离对图谱进行了分析. 结果表明, 该阵列可以鉴别模式蛋白牛血清白蛋白(BSA)、 牛血红蛋白(BHb)和卵清白蛋白(Ova)及其混合物, 且有望实现定量分析. 此外, 阵列的高敏感性使其不仅能识别天然蛋白质和不同变性程度的蛋白质, 还能对其热变性过程进行可视化实时监控. 该阵列产生的特殊颜色变化与蛋白质的空间构型、 微环境pH值的差异及溶解度有关. 因此, 该方法不仅能实现对蛋白质的快速识别, 为蛋白质热变性机理的研究提供新途径, 而且在临床医学和食品安全等的实时快速检测方面有潜在的应用价值.     

基于CoP纳米阵列的亚硝酸根传感器的研究

亚硝酸盐对环境和人体健康有着不利的影响,人体长期食用含大量亚硝酸盐的食物有致癌的风险,对亚硝酸盐的分析和检测是非常重要的. 开发高效的电催化剂,从而实现高灵敏度和高选择性的亚硝酸盐检测具有十分重要的意义. 作者通过先水热再低温磷化获得了磷化钴纳米阵列（CoP/TM）.电化学测试结果表明,所构建的CoP/TM电极对亚硝酸盐的还原具有高效的催化作用,线性检测范围为1.0 μmol·L^-1到1.0 mmol·L^-1,检测下限为18 nmol·L^-1（S/N=3）,响应灵敏度为17781 μA·(mmol·L^-1)^-1·cm^-2,响应时间小于3 s,选择性良好.     

基于功能化纳米材料的光化学阵列传感器

阵列传感器采用人工模拟嗅觉系统的传感模式,实现多点信息的同时获取,极大地提高了分析效率,在公共安全、环境监测、医学检测等领域具有广阔的应用前景。其中,光化学阵列传感器因灵敏度高、输出信号丰富等优点而备受关注。近年来,为了进一步提高阵列传感器的识别能力和灵敏度,功能化纳米材料被广泛应用于光化学阵列传感器以增加传感材料的种类和发展新的传感方法。本文按照使用的光谱检测技术不同,详细介绍了功能化纳米材料在荧光、比色、催化发光和多通道阵列传感器等4类光化学阵列传感器中的应用。     

压电晶体传感器阵列用于含乙醇的蒸气检测

将多个表面涂有不同选择性吸附材料的压电晶体传感器组成阵列，用于混合有机溶剂蒸气中乙醇的检测。对阵列输出的数据，采用逐步判别法进行二类判别，可以检测混合蒸气中少量的乙醇，采用主成分回归法，可由阵列输出数据预测未知样品中乙醇的浓度。     

压电晶体传感器阵列测定装置及数据采集系统

研究了一种利用微机控制测量和采集压电晶体传感器阵列振荡频率的智能型仪器。介绍了其硬件及数据采集软件的功能，结构等。     

气体传感器阵列信号的盲分离研究

本文在使用一个四单元微热板式集成气体传感器阵列测试煤矿中的两种主要易燃易爆气体一氧化碳和甲烷的基础上, 将气体传感器阵列与盲信号分离技术相结合, 讨论了混合气体分析的盲可辨识性, 并使用盲信号分离中的一种主要方法独立分量分析法(ICA)进行了分析和验证.     

基于主客体识别作用构建的电化学发光传感器检测丹参中汞离子

使用联吡啶钌(Ru(bpy)32+)/β-环糊精-金纳米粒子(β-CD-AuNPs)/全氟磺酸(Nafion)复合物和二茂铁标记(Fc)的DNA探针(Fc-DNA)构建了电化学发光(Electrochemiluminescence,ECL)生物传感器,将其用于检测中药材丹参中的汞离子。 该传感器包含ECL发光基底和ECL强度开关两部分,将Ru(bpy)32+/β-CD-AuNPs/Nafion组装到玻碳电极(GCE)上构成发光基底,产生稳定的ECL信号;Fc-DNA探针作为ECL信号开关,通过分子识别策略设计,利用β-CD与Fc的主客体相互作用与β-CD-AuNPs相连。 该检测方法和以往的汞离子检测方法相比,具有背景信号低、选择性高、仪器简单、操作快速等特点。 该 “Off-On” 电致化学发光生物传感器在0.04~800 ng/mL范围内对Hg²⁺具有良好的线性响应,检测限为0.02 ng/mL(S/N=3)。     

A Generic Design of a Flow-Through Potentiometric Sensor Array

 In this paper, a flow-through potentiometric microsensor is described which is based on semi-permeable tubing. The ion selective electrodes proposed are of the liquid membrane type in which a dialysis tube captures the ion selective cocktail. Ion selective sensors and a reference electrode based on the same design were constructed by guiding a 0.3 mm diameter dialysis tube through a cavity precision machined in Perspex?. Commercia lly available ionophore or ion-exchanger cocktails were applied to provide ion selectivity whilst a saturated KCl solution was used in the reference electrode. A number of flow-through microsensors selective to different ions (Na, K, Li, pH) were constructed and tested. Each showed good performance in a broad range of concentrations. Advantages of the proposed approach are the generic technology to make sensors with incorporate d reference electrodes, capable of measuring a wide variety of analytes for which cocktails are readily available and the fact that sub-microliter amounts of sample can be measured. Secondly, in comparison to other sensors applied in microchannels, the impedance of the flow-through sensor is much smaller because of the relatively large sensing surface formed by the tube wall. Moreover, the use of dialysis tubing enables easy integration with a so-called microdialysis probe for in-vivo sampling of the blood stream or subcutaneous tissue. Received December 6, 1999. Revision March 24, 2000.     

Kinetically-Locked Metallomacrocycle for Host-Guest Chemistry with Bulky Anions

As a robust and large molecular receptor, a kinetically-locked trinuclear Co(III) macrocycle was synthesized with bis(β-diketone) ligands having large π-panels of 9,10-diphenylanthracene moieties via a combination of Co(II)-assisted self-assembly and subsequent oxidation of the metal centers. The X-ray structure revealed that the macrocycle had a discrete nanocavity of more than 300 ų, which was surrounded by three anthracenyl panels in the middle. As the macrocycle has three cationic centres on each metal ion and a large cavity, it acts as a guest receptor for sodium tetraphenylborate. The binding constant was estimated to be 4.0×10⁻² M⁻¹ from ¹H NMR titration experiments, whereas no interaction was observed between the macrocycle and potassium 1-adamantanecarboxylate.     

一种新型分子印迹聚合物基的化学发光阵列传感器

建立了一种分子印迹-化学发光阵列传感器测定甘氨酸的新方法. 该方法以甘氨酸为模板分子, 合成了分子印迹聚合物微球, 将该聚合物微球固定在96孔板上, 用它来识别丹磺酰氯标记的甘氨酸(Dns-Gly). 最后加入化学发光试剂(TCPO-H2O2-咪唑), 测量相对化学发光强度定量检测甘氨酸. 在最佳试验条件下, 相对化学发光强度和甘氨酸的浓度在0.2～60 μmol/L范围内成良好的线性关系, 相关系数为r＝0.9972, 方法的检出限为0.07 μmol/L, 对1 μmol/L甘氨酸溶液进行11次平行测定, 相对标准偏差为3.3% (n＝11). 由于以甘氨酸为模板分子合成出来的分子印迹聚合物空腔比较小, 避免了非特异性吸附, 使它在识别丹磺酰氯标记的甘氨酸时特异性、响应速度和灵敏度都有所增强.     

Self-Assembled Peptidyl Aggregates for the Fluorogenic Recognition of Mitochondrial DNA G-Quadruplexes

The selective monitoring of G-quadruplex (G4) structures in living cells is important to elucidate their functions and reveal their value as diagnostic or therapeutic targets. Here we report a fluorogenic probe ( CV2 ) able to selectively light-up parallel G4 DNA over antiparallel topologies. CV2 was constructed by conjugating the excimer-forming CV dye with a peptide sequence (l -Arg-l -Gly-glutaric acid) that specifically recognizes G4s. CV2 forms self-assembled, red excimer-emitting nanoaggregates in aqueous media, but specific binding to G4s triggers its disassembly into rigidified monomeric dyes, leading to a dramatic fluorescence enhancement. Moreover, selective permeation of CV2 stains G4s in mitochondria over the nucleus. CV2 was employed for tracking the folding and unfolding of G4s in living cells, and for monitoring mitochondrial DNA (mtDNA) damage. These properties make CV2 appealing to investigate the possible roles of mtDNA G4s in diseases that involve mitochondrial dysfunction.     

Screening of Synthetic Cathinones by Potentiometric Sensor Array and Chemometrics

This work demonstrates the analytical applicability of single ion-selective membranes (ISMs) and potentiometric sensor array to distinguish and detect cathinone derivatives. Potentiometric data from ISMs based on cation exchanger and varying content of calix[4]arene derivative were processed by principal component analysis (PCA). Such a combination of methods allowed discriminating various individual synthetic cathinones and their recognition from the mixture comprising primary amines (substituted amphetamines+aminoindane). Analytical parameters of ISM containing 1wt % of calix[4]arene derivative were sufficient to detect 1.0×10⁻⁴ mol.l⁻¹ 1-(4-fluorophenyl)-2-(ethylamino)butan-1-one and 2-(methylamino)-1-phenylbutan-1-one (buphedrone) in both model and saliva samples.