基于胸腺嘧啶碱基错配的汞离子传感器研究进展

基于汞离子和胸腺嘧啶的质子取代反应,可形成T-Hg(Ⅱ)-T碱基错配结构,该结构可作为新型汞离子传感器的良好识别元件。相较于传统汞离子检测方法在效率与精度上的不足,以T-Hg(Ⅱ)-T碱基错配结构为识别基团的新型汞离子传感器具有一定优势。该文综述了以T-Hg(Ⅱ)-T结构为识别基团,以不同类型报告基团为基础的汞离子传感器的研究进展与趋势,从而为后续汞离子传感器的开发提供参考。     

基于寡核苷酸链的汞离子荧光生物传感器

基于G-四链体结构和卟啉类化合物N-甲基卟啉二丙酸IX(NMM)结合产生强烈的荧光,利用T-Hg(Ⅱ)-T错配对汞离子(Hg2+)的特异性识别,建立了一种简单、灵敏、高效的Hg2+检测新方法.在富含鸟嘌呤(G)寡核苷酸链中,引入了大量胸腺嘧啶(T).在没有Hg2+存在时,可以自发形成G-四链体结构,与NMM结合产生强烈的荧光;在Hg2+存在时,可与另一条富含T序列的互补链通过T-Hg(Ⅱ)-T特异性结合,形成双链DNA分子,从而导致G-四链体结构不能产生.优化后最佳实验条件为:缓冲溶液的pH=6.7,20 mmol/LKCl,2.5 μmol/L NMM,反应时间为2h.在优化条件下,体系的荧光强度变化值与Hg2+浓度呈现良好的线性关系,线性范围为50～ 1000 nmol/L,检出限为22.8 nmol/L(30).此生物荧光传感器对Hg2+具有良好的选择性.实际水样中Hg2+的加标回收率为106.1％ ～ 107.8％,可以满足实际水样品中Hg2+的检测要求.     

荧光共振能量转移高灵敏检测汞离子和半胱氨酸

开发了一种简单快速的荧光探针,该探针在DNA的3’端标记荧光素并利用[T-Hg(II)-T]复合结构对荧光进行猝灭,荧光素与[T-Hg(II)-T]复合结构之间发生荧光共振能量转移。在对探针链长度以及pH和反应时间等实验条件进行优化后,该荧光探针对汞离子具有较高的选择性,用于汞离子分析时检出限可以达到纳摩尔级。当加入半胱氨酸,由于形成了半胱氨酸-汞离子复合结构,[T-Hg(II)-T]复合结构被破坏,荧光强度大量的恢复。利用此原理可以对半胱氨酸进行分析,检出限也可以达纳摩尔级。该荧光探针利用一条廉价的T碱基适配体链所构筑,相比传统的荧光探针有着独特的优势。     

基因编码荧光探针的构建与应用

基因编码荧光探针能够可视化探测活细胞中多种分析物及其相关分子事件,已成为细胞生物学等生命科学研究的强大分子工具.本文介绍了基因编码荧光探针的类型和主要应用场景,归纳了现有探针的优点和存在的问题,并对其未来发展进行了展望.     

新型SARS-CoV 3CL蛋白酶荧光多肽底物的设计、制备及其酶动力学研究

以邻氨基苯甲酸（Abz）为荧光发射基团、2，4-二硝基苯基乙二胺（rdanp）为荧光猝灭基团，设计合成了SARS，CoV3CL蛋白酶的新型荧光多肽底物：H2N-E（Eddnp）STLQSGLK（Abz）-CONH2．用液相色谱-质谱（LC—MS）联用技术进行了表征，表明该多肽底物能被SAILS-CoV 3CL蛋白酶识别，并在QS之间被专一性酶解．另外，利用该多肽底物的荧光共振能量转移（FRET）特性，对SARS—CoV 3CL蛋白酶的酶解动力学性质进行了研究，结果表明，此荧光多肽底物可以作为荧光探针，应用于SARS—CoV 3CL蛋白酶活性的测定及其抑制剂的筛选．     

基于罗丹明的重金属和过渡金属阳离子荧光分子探针研究进展

介绍了近五年来以罗丹明为母体的重金属和过渡金属阳离子荧光分子探针领域的研究进展.文中按照荧光团和识别基团之间连接臂的不同对国内外各研究组的工作进展进行归类总结,并对探针设计的思路、探针的性质和应用给出了简要介绍.     

多肽荧光传感器检测铜离子

基于铜离子对罗丹明B标记的多肽的荧光猝灭作用,构建了一种用于铜离子检测的荧光传感器.利用共振光散射分析、紫外-可见吸收光谱、荧光寿命测试和圆二色光谱研究了铜离子检测的传感机理,发现铜离子的加入诱导多肽结构发生变化而使罗丹明B荧光团彼此靠近,从而导致铜离子与多肽之间发生聚集诱导荧光猝灭.实验结果表明,该传感器检测铜离子的线性范围为5×10^-4～1×10^-2μmol/L和0.1～7μmol/L,检出限为0.29 nmol/L,且拥有良好的选择性,能用于湖水样品中铜离子的检测.     

铅、汞、镉离子的荧光传感器研究进展

化学传感器提供了方便、快捷、廉价的分析检测有毒重金属离子的方法,并具有很高的灵敏度和选择性.它在环境科学、分析化学以及生命科学等领域有广泛的应用前景.本文分别综述了pb²⁺、Hg²⁺、Cd²⁺几种有毒重离子化学传感器的最新研究进展,并展望了该领域的发展趋势.     

汞离子荧光、比色传感器

基于主客体识别的汞离子比色、荧光传感器由于使用方法简单、灵敏度高、不需要昂贵仪器等优势,受到了越来越多的关注。本文综述了近年来汞离子比色和荧光传感器的研究进展。本文根据作用机理将汞离子比色、荧光传感器分成三类,即通过特殊反应识别汞离子的传感器,通过配位作用识别汞离子的传感器以及基于纳米材料的汞离子传感器。其中通过特殊反应识别的传感器根据具体反应类型又可分成汞离子诱导的罗丹明上的内酰胺环开环型、汞离子与含硫(硒)的受体发生脱硫(硒)反应使受体氧化或关环型、汞离子与受体发生加汞化反应型和汞离子使受体发生汞离子催化的化学反应型这四类。本文对这些类型的汞离子传感器从设计原理、识别性能和机理等方面进行了介绍,并展望了该领域的研究方向。     

基于荧光共振能量转移的核酸适配体传感器检测环丙沙星

建立了一种基于荧光共振能量转移（FRET）的核酸适配体传感器,并用于检测实际水体和牛奶中的环丙沙星（CIP）。为了防止羧基荧光素（FAM）被CIP猝灭,FAM和四甲基罗丹明（TAMRA）分别标记在互补单链DNA(FAM-cDNA)和适配体（TAMRA-APT）,通过DNA杂交发生FRET, TAMRA有效猝灭FAM的荧光。CIP加入后,其与FAM-cDNA发生亲和力竞争反应,CIP与TAMRA-APT形成结构更稳定的CIP/TAMRA-APT复合物,使体系FAM的荧光恢复。在优化条件下,本方法对CIP表现出高灵敏度和高选择性,检测浓度线性范围为0.01～1μmol/L,检出限为6 nmol/L;对实际水样和牛奶的加标回收率为90.4%～113.2%,相对标准偏差为1.8%～11%。该荧光适配体传感器具有成本低、灵敏度高、特异性好等优点,在环境中CIP残留快速检测方面具有良好的应用潜力。     

Tetrahydrofuran Activates Fluorescence Resonant Energy Transfer from a Cationic Conjugated Polyelectrolyte to Fluorescein‐Labeled DNA in Aqueous Media

A cationic water‐soluble conjugated polyelectrolyte, poly[9,9‐bis(6′′‐(N,N,N‐trimethylammonium)hexyl)fluorene‐co‐alt‐2,5‐bis(6′‐(N,N,N‐trimethylammonium)hexyloxyphenylene) tetrabromide], was synthesized. Fluorescence resonant energy transfer (FRET) experiments between the polymer and fluorescein‐labeled single‐stranded DNA (ssDNA‐Fl) were conducted in aqueous buffer and THF/buffer mixtures. Weak fluorescence emission in aqueous buffer was observed upon excitation of the polymer, whereas addition of THF turned on the fluorescence. Fluorescence self‐quenching of ssDNA‐Fl in the ssDNA‐Fl/polymer complexes as well as electron transfer from the polymer to fluorescein may account for the low fluorescence emission in buffer. The improved sensitization of fluorescence by the polymer observed in THF/buffer could be attributed to the weaker binding between the polymer and ssDNA‐Fl and a decrease in dielectric constant of the solvent mixture, which disfavors electron transfer. THF‐assisted signal sensitization was also observed for the polymer and fluorescein‐labeled double‐stranded DNA (dsDNA‐Fl). These results indicate that the use of cosolvent provides a strategy to improve the detection sensitivity for biosensors based on the optical amplification provided by conjugated polymers.     

铜（II）离子对脱镁叶绿素-a荧光猝灭的研究

本文介绍了一种利用荧光熄灭定量的测定铜（II）的新方法。从新鲜菠菜中提取叶绿素-a,用高氯酸溶液处理,制得脱镁叶绿素-a。测量脱镁叶绿素-a的紫外-可见吸收光谱,观测到505和535nm处有特征吸收峰。在60 ℃水浴中,脱镁叶绿素-a的丙酮溶液与铜（II）离子水溶液混合,5分钟后发现混合液颜色变绿,505和535 nm处吸收峰消失。铜（II）离子水溶液与脱镁叶绿素-a的丙酮溶液混合后发生荧光猝灭现象,而类似浓度的其它生理离子在相同反应条件下对脱镁叶绿素-a的荧光猝灭现象不明显。 研究了铜（II）离子与脱镁叶绿素-a的反应时间,反应温度对荧光强度衰减的影响。并通过阿累尼乌斯经验关系估算铜（II）离子与脱镁叶绿素-a反应的活化能约为10 ±1kJ·mol-1。研究了铜（II）离子的浓度对脱镁叶绿素-a的丙酮溶液荧光强度的影响,在8.0×10-5 ～8.0×10-7 mol·dm-3范围内,铜（II）离子的浓度与混合液的荧光强度成线性衰减关系,检测限可达8.0×10-7 mol·dm-3。利用脱镁叶绿素-a的丙酮溶液的荧光强度变化测量,有望发展成为一种检测铜（II）离子的新方法。     

Selective Detection of Mercury（Ⅱ） and Copper（Ⅱ） Based on the Opposite Size-dependent Fluorescence Quenching of CdTe Quantum Dots

Three different size CdTe quantum dots （QDs） capped by 3-mercaptopropionic acid （MPA） have been prepared in aqueous solutions, and their interactions with Cu^2＋ and Hg^2＋ have been investigated. The opposite size-dependent fluorescence quenching of CdTe QDs by Hg^2＋ and Cu^2＋ was observed： Hg^2＋ quenched smaller particles more efficiently than larger ones while larger particles were more markedly quenched by Cu^2＋. Based on the different size responses, Hg^2＋ and Cu^2＋ were respectively detected with high sensitivity and selectivity, for the first time, using the QDs with different sizes but the same components and capping ligands.     

Ion Association and Hydration in Aqueous Solutions of Nickel(II) and Cobalt(II) Sulfate

Aqueous solutions of nickel(II) and cobalt(II) sulfate have been investigated at 25 ^∘C by dielectric relaxation spectroscopy (DRS) over a wide range of frequencies (0.2 ≤ ν (GHz) ≤ 89) and salt concentrations (0.025 ≤ c(mol-L⁻¹) ≤ 1.4). The spectra indicate, as for MgSO₄(aq) studied previously, the simultaneous presence of double solvent-separated, solvent-shared and contact ion pairs in both NiSO₄(aq) and CoSO₄(aq). The stepwise formation constants for each ion-pair type and the overall association constant, obtained from the data are in good agreement with ultrasonic relaxation and other estimates. The DR spectra at higher concentrations (c ≥ 0.5 mol-L⁻¹) suggest the existence of a nonlinear triple ion M₂SO₄²⁺(aq). Consistent with the very strong hydration of the salts, which have ‘effective’ hydration numbers approaching 27 at infinite dilution, there are no significant differences in any of the relaxation or thermodynamic parameters for NiSO₄(aq) and CoSO₄(aq), except that the triple ion appears to be somewhat more stable for the latter.     

Excitation Induced Emission Color Change Based on Eu(III)‐Zn(II)‐containing Polymer Complex

A novel polymer P‐1 is prepared by the reaction of the monomer 5,5′‐divinyl‐2,2′‐bipyridine and Salen‐Zn(II) via Heck cross coupling. Interestingly, P‐1 can further incorporate with Eu(TTA)₃·2H₂O to generate copolymer P‐2 with two different metal centers. P‐2 exhibits exceptional dual emissive properties which can be tuned by excitation wavelength. For example, an orange fluorescence can be obtained when P‐2 is excited at 430 nm, whereas a red emission with a huge Stoke shift of 57 nm is observed when it is excited at 345 nm. The high wavelength emission can be attributed to Eu(III) (⁵D₀→⁷F₂), which is lit by an effective photoinduced energy transfer process between P‐1 and the Eu(TTA)₃ complex. The properties of P‐2 have led to a better understanding of the energy transfer process between P‐1 and Eu(TTA)₃ moieties.     

Amplified Fluorescence Turn‐On Assay for Mercury(II) Detection and Quantification based on Conjugated Polymer and Silica Nanoparticles

An amplified fluorescence turn‐on assay for mercury(II) detection and quantification was developed. This method makes use of specific thymine/mercury(II)/thymine coordination to capture Fl‐labeled DNA onto NP surface. Addition of a cationic conjugated polymer leads to an amplified Fl signal in solution. A sigmoidal Hg²⁺ working curve is obtained at fixed [NP] with a detection limit of 0.1 × 10⁻⁶ M . However, by reducing [Hg²⁺] and [NP] simultaneously, while maintaining [Hg²⁺]:[DNA duplex] = 3:1, a linear calibration curve is observed with a detection limit of 5 × 10⁻⁹ M . The CCP‐assisted mercury(II) assay shows potential applications in environmental mercury detection and for industrial process control.