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。     

基于荧光小分子2-氨基-7-甲基-1,8-萘啶对C碱基的识别检测DNA双链中的C/C错配

单碱基错配是单核苷酸多态性(SNPs)的一种,是导致突变的DNA损伤类型之一.单碱基错配的检测对于从分子水平上阐明多种疾病形成的原因,实现基因水平的治疗都是至关重要的前提条件.发展具有高灵敏度、高选择性的单碱基错配检测方法势在必行.常用的单碱基错配检测方法包括凝胶电泳、荧光检测、SPR和质谱检测等.本文采用2-氨基-7-甲基-1,8-萘啶(AMND)作为荧光探针,AMND能嵌入双链DNA(ds-DNA)中的错配位点,并通过氢键识别错配碱基,这一结合过程伴随探针小分子的荧光淬灭,通过检测荧光淬灭现象实现单碱基错配及错配碱基类型的识别,建立了SNPs荧光分型方法.     

量子点荧光探针检测抗坏血酸

以巯基丙酸（MPA）为稳定剂水相合成了高荧光CdTe量子点. 向量子点溶液中加入Mn2+,由于量子点表面状态发生改变而使其荧光淬灭,加入抗坏血酸后量子点荧光又得以恢复,且荧光恢复程度与抗坏血酸的浓度线性相关,从而建立了基于量子点的荧光“开关”探针检测抗坏血酸的新方法. 当CdTe量子点的浓度为1.67 uM（量子点的尺寸为1.91nm）,加入的Mn2+浓度为0.25 mM时,在优化的实验条件下,检测抗坏血酸的线性范围为0.25~16 uM,检出限为36 nM. 相对标准偏差为2.5%(10 uM, n=11). 该探针可用于维生素C药片和人血浆中抗坏血酸的快速、灵敏和选择性检测.     

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。     

对苯二胺荧光探针测定水质样品中的溶解态汞

为获得水质样品中的溶解态汞简便、灵敏的测定方法,以含有荧光基团和氨基活性基团的对苯二胺作为荧光探针,基于其荧光猝灭程度与Hg(Ⅱ)浓度呈线性关系,建立荧光光度法测定水质样品中溶解态汞的检测方法。对缓冲体系的类型、pH值、浓度以及荧光探针的浓度等条件进行实验,确定采用pH 5.0的0.010 mol/L AABS体系和0.40 μg/mL对苯二胺荧光探针的荧光探针实验条件,并应用于实际水质样品中。结果表明,当Hg(Ⅱ)浓度在0.64 μg/mL ~1.36μg/mL内,荧光探针对苯二胺浓度的荧光淬灭程度与Hg(Ⅱ)浓度成良好的线性关系(R=0.9991),重复性实验的相对标准偏差为0.72 %,方法检出限为0.032 μg/mL,加标回收率均在90%~110%之间。该方法简便、灵敏度高、选择性好、可用于实际水质样品中溶解态汞的测定,具有较好的应用前景。     

基于T-Hg2+-T及G四聚体自身熄灭能力的“Turnon”型单标记DNA荧光探针用于碘离子的检测

利用G四聚体可以熄灭荧光的特性以及T-Hg2+-T的特殊结构, 发展了一种简便的"Turn on"型碘离子检测新方法. 设计了一条5'端标有荧光基团的富T序列, 3'端采用能形成G四聚体的富G序列代替传统的熄灭基团. 加入汞离子后, 富T序列形成T-Hg2+-T机构发生折叠, G四聚体靠近荧光基团, 发生光诱导电子转移, 使荧光被熄灭. 若加入碘离子, 碘离子会与汞离子形成较稳定的配合物, 汞离子从DNA上被竞争下来, 探针的荧光得以恢复, 且荧光强度与50～500 nmol/L的碘离子呈良好线性关系, 检出限为30 nmol/L. 本方法选择性好, 10倍于碘离子浓度的其它常见阴离子干扰较小. 检测自来水样中碘离子的回收率为92%～109%, 相对标准偏差RSD<4%(n=4).     

具有聚集诱导发光性质二芳基喹喔啉衍生物及其在检测Hg2+的应用

荧光传感器由于具有高灵敏度和高选择性,在检测化学方面具有很高的应用。我们合成了具有活性荧光团的聚集诱导发光物质：二芳基喹喔啉衍生物（1-4）类物质,并对其进行表征。化合物3同时具有AIE特征的二芳基喹喔啉、和Hg2+具有特殊反应1,3-二硫杂环戊二烯-2-硫酮的基团,我们将这两个特征基团耦合在同一个化合物之中,从而构建了一类新的“开-启”型汞离子荧光传感器。     

双氰基二苯代乙烯型双光子荧光汞离子探针

分别以双氰基二苯代乙烯(DCS)和双[2-(2-羟乙基硫基)乙基]氨(HSA)为双光子荧光团和汞离子受体,合成了双光子荧光汞离子探针(DHg),并对其结构进行了分析.实验结果表明,DHg在甲苯、乙腈和水中的荧光量子产率(Φ)分别为0.78,0.42和0.20,对汞离子的络合常数通过单、双光子荧光滴定分别拟合为lg K=5.47±0.02和lg K=5.34±0.02.DHg在水溶液中对汞离子具有优良的选择性和高的灵敏性,可用于中性环境中汞离子的检测.DHg的双光子吸收截面(δTPA)在水溶液中高达840 GM,可用于细胞中汞离子的检测与成像.     

一种近红外发射荧光探针的合成及其荧光增强识别Hg2+

汞离子(Hg~(2+))由于高毒性以及容易对环境和人体造成损害,其检测越来越受到人们的重视。本文基于4-(二乙氨基)水杨醛设计合成了一种近红外发射荧光探针L,该探针可在MeCN/HEPES(体积比2/8,pH=7.4)缓冲溶液中高选择性地荧光增强识别Hg~(2+),其具有合成简便、抗干扰能力强、适用pH范围宽等特点。进一步研究表明,探针L可用于真实水样中Hg~(2+)的检测。     

基于罗丹明荧光信号报告基团的细胞通透性铜离子荧光探针

分别以罗丹明B和罗丹明6G为荧光信号报告基团,以增强水溶性为目的的羟乙基肼为修饰基团,合成了反应型的Cu_(2+)离子选择性荧光探针分子L1和L2.紫外光谱和荧光光谱等分析结果表明,探针分子L1和L2对Cu_(2+)离子具有高灵敏度、高选择性的光谱识别行为.探针分子对Cu_(2+)离子的识别过程是通过Cu_(2+)离子催化水解控制氧杂蒽荧光信号的螺环酰肼基团实现荧光信号的开启,从而达到识别检测Cu_(2+)离子的目的,对Cu_(2+)离子的检出限均可达到10-8mol/L量级.同时,探针分子对常见金属离子和铵离子均具有较强的抗干扰能力.由于羟乙基肼的引入增强了探针的水溶性,使得探针L1和L2具有良好的细胞通透性和低毒性,实现了其对β-胰岛细胞(INS-1细胞)中Cu_(2+)离子的荧光成像检测.     

Highly Sensitive Electrochemiluminescence Detection of Mercury(II) Ions Based on DNA‐Linked Luminol‐Au NPs Superstructure

A novel highly sensitive electrochemiluminescence (ECL) detection protocol for mercury(II) ions was developed. Based on the strong and stable thymine? thymine mismatches complexes coordination chemistry, mercury(II) ions can specifically bind to a designed DNA strand, leading to the release of the complimentary DNA strand. The released DNA strand was then captured by magnetic beads modified with specific DNA, and then through the formation of DNA‐linked luminol‐Au nanoparticles (NPs) superstructure, a specific ECL system for mercury(II) ions was developed. Using 3‐aminopropyl‐triethoxysilane as an effective enhancer, the ECL system can detect Hg²⁺ ion within a linear range from 2.0×10^?10 mol L^?1 to 2.0×10^?8 M, with a detection limit as low as 1.05×10^?10 M (3σ). Moreover, this ECL system is highly specific for Hg²⁺, without interference from other commonly coexisted metal ions, and it can be used for the analysis of real samples.     

Highly Sensitive Fluorometric Hg2+ Biosensor with a Mercury(II)‐Speci?c Oligonucleotide (MSO) Probe and Water‐Soluble Graphene Oxide (WSGO)

A highly sensitive and selective, "turn‐on" and simple Hg²⁺ biosensor is reported by using water‐soluble graphene oxide (WSGO) and dye‐labeled mercury(II)‐specific oligonucleotide (MSO) probe. The probe is rich of thymine (T) and can readily form the stem‐loop structure which consists of the T‐Hg²⁺‐T configuration. In the absence of Hg²⁺, the probe exists as a random coil conformation which can be readily adsorbed on the surface of WSGO by strong noncovalent binding of bases, as a result, the fluorescence of the dye labeled on the terminus of the MSO is strongly quenched by the efficient electron/energy transfer from the dye to WSGO. Upon addition of Hg²⁺, the formation of the T‐Hg²⁺‐T structure releases the MSO from the surface of WSGO, resulting in a restoration of the fluorescence of dye‐labeled MSO probe. Based on this observation, a highly sensitive and selective Hg²⁺ sensor is developed, which can work with "turn‐on" mode in aqueous solutions at room temperature. By using the fluorometric method, the limit of detection for Hg²⁺ can reach picomolar range (187 pmol·L^?1), and it is demonstrated that the biosensor is highly selective and only minimally perturbed by a wide range of non‐specific metal ions.     

A Reversible and Highly Selective Fluorescent Sensor for Mercury(II) Using Poly(thiophene)s that Contain Thymine Moieties

Summary: A reversible and highly selective assay method has been developed to detect mercury(II ) (Hg²⁺) ions using a conjugated polymer (CP). The transduction mechanism is based on Hg²⁺‐mediated interpolymer π‐stacking aggregation, which results in the fluorescence self‐quenching of the CP. CPs that contain thymine moieties, poly[3‐(N‐thymin‐1‐ylacetyl)ethylamine‐thiophene] (PTT), have been synthesized and characterized. In the absence of Hg²⁺ ions, the PTT chains remain separated from each other and the CP exhibits strong fluorescence emission. Upon adding Hg²⁺ ions, the formation of interpolymer π‐stacking aggregation induced by specific thymine–Hg–thymine interactions results in the fluorescence quenching of PTT. Distinguishing aspects of this assay include the signal amplification of CPs and the specific binding of Hg²⁺ ions to thymine‐thymine (T–T) base pairs.

The binding of Hg²⁺ ions causes the separate conducting polymer chains to aggregate with subsequent fluorescence self‐quenching.     

Aptamer-modified AuRe Nanoalloy Probe for Trace Hg2+ Using Resonance Scattering as Detection Technique

The AuRe nanoalloy particles in molar ratio of 9:1 were prepared by sodium borohydride procedure, and modified by single strand DNA (ssDNA) to prepare an aptamer AuRe nanoprobe (AuRessDNA) for Hg²⁺. In the pH 7.0 Na₂HPO₄‐NaH₂PO₄ buffer solution and in the presence of NaCl, Hg²⁺ interacted with AuRessDNA to form double‐stranded T‐Hg²⁺‐T mismatched and release AuRe nanoparticles that aggregate to large AuRe nanoparticles clusters causing the resonance scattering (RS) peak red shifting and the RS intensity enhanced linearly. On those grounds, 0.067–33.3 nmol·L^?1 Hg²⁺ can be detected rapidly by the aptamer‐modified AuRe nanoparticles RS assay, with a detection limit of 0.04 nmol·L^?1 Hg²⁺. If the aggregated AuRe particles were removed by membrane filtration, the excess AuRessDNA in the filtration solution exhibits catalytic effect on the new Te particle reaction between Na₂TeO₄ and SnCl₂. As the concentration of Hg²⁺ increased, the AuRessDNA nanoparticles in the filtrate solution decreased, the RS intensity at 734 nm decreased linearly. The Hg²⁺ concentration (c) in the range of 0.00133–0.267 nmol·L^?1 was linear to the decreased RS intensity (ΔI_734nm), with a regression equation of ΔI= ?786.4c?4.4, a correlation coefficient of 0.9975, and a detection limit of 0.9 pmol·L^?1 Hg²⁺. This method was applied to the detection of Hg²⁺ in water samples, with satisfactory results.     

High Sensibility of Quantum Dots to Metal Ions Inspired by Hydroxyapatite Microbeads

An approach for the sensitive and selective determination of Ag⁺, Cu²⁺ and Hg²⁺ ions was developed based on the fluorescence quenching of mercaptopropionic acid (MPA) capped CdTe quantum dots in the existence of hydroxyapatite (HAP) nanoribbon spherulites. Among various metal ions investigated, it was found that the fluorescence of CdTe QDs was only sensitive to Ag⁺, Cu²⁺ and Hg²⁺ ions. The addition of HAP into the CdTe system could bring forward a sensitivity improvement of about 1 to 2 orders of magnitude in the detection of Ag⁺ and Cu²⁺ compared with the plain CdTe system without the existence of HAP; while there was no sensitization effect for Hg²⁺. Under optimal conditions, the detection limits for Ag⁺, Cu²⁺ and Hg²⁺ were 20, 56 and 3.0 nmol·L^?1, respectively, and the linear ranges were 0.02–50, 0.056–54 and 0.003–2.4 µmol·L^?1, respectively. Mechanisms of both QDs fluorescence quenching by metal ions and the sensitization effect by HAP were also discussed.     

Rapid Determination of Free Amino Acids in Milk by Microchip Electrophoresis Coupled with Laser‐induced Fluorescence Detection

A simple and sensitive method for determination of free amino acids in milk by microchip electrophoresis (MCE) coupled with laser‐induced fluorescence (LIF) detection was developed. Seven kinds of standard amino acids were derivated with sulfoindocyanine succinimidyl ester (Cy5) and then perfectly measured by MCE‐LIF within 150 s. The parameters of MCE separation were carefully investigated to obtain the optimal conditions: 100 mmol·L^?1 sodium borate solution (pH 10.0) as running buffer solution, 0.8 kV as injection voltage, 2.2 kV as separation voltage etc. The linear range of the detection of amino acids was from 0.01 µmol·L^?1 to 1.0 µmol·L^?1 and the detection limit was as low as about 1.0 nmol·L^?1. This MCE‐LIF method was applied to the measurements of free amino acids in actual milk samples and satisfactory experimental results were achieved.     

A novel Hg2+ fluorescence sensor TPE-TSC based on aggregation-induced emission

Abstract

A fluorescent sensor TPE-TSC with aggregation induced emission (AIE) characteristic is synthesized for detecting Hg²⁺ by attaching thiosemicarbazide (TSC) unit into tetraphenylethylene (TPE) group. TPE-TSC exhibits intense green emission in DMSO/H₂O (V:V?=?1:9) solution with the formation of the aggregation. TPE-TSC shows outstanding fluorescence quenching toward Hg²⁺ over other metal ions due to the formation of complex TPE-TSC/Hg²⁺ with a 2:1 binding ratio. The detection limit of TPE-TSC for Hg²⁺ is 1?×?10^?5 mol·L^?1.     

Selective Detection of Hg2+ Ions with Boron Dipyrromethene‐Based Fluorescent Probes Appended with a Bis(1,2,3‐triazole)amino Receptor

By using a copper‐promoted alkyne–azide cycloaddition reaction, two boron dipyrromethene (BODIPY) derivatives bearing a bis(1,2,3‐triazole)amino receptor at the meso position were prepared and characterized. For the analogue with two terminal triethylene glycol chains, the fluorescence emission at 509 nm responded selectively toward Hg²⁺ ions, which greatly increased the fluorescence quantum yield from 0.003 to 0.25 as a result of inhibition of the photoinduced electron transfer (PET) process. By introducing two additional rhodamine moieties at the termini, the resulting conjugate could also detect Hg²⁺ ions in a highly selective manner. Upon excitation at the BODIPY core, the fluorescence emission of rhodamine at 580 nm was observed and the intensity increased substantially upon addition of Hg²⁺ ions due to inhibition of the PET process followed by highly efficient fluorescence resonance energy transfer (FRET) from the BODIPY core to the rhodamine moieties. The Hg²⁺‐responsive fluorescence change of these two probes could be easily seen with the naked eye. The binding stoichiometry between the probes and Hg²⁺ ions in CH₃CN was determined to be 1:2 by Job′s plot analysis and ¹H NMR titration, and the binding constants were found to be (1.2±0.1)×10¹¹ m ^?2 and (1.3±0.3)×10¹⁰ m ^?2, respectively. The overall results suggest that these two BODIPY derivatives can serve as highly selective fluorescent probes for Hg²⁺ ions. The rhodamine derivative makes use of a combined PET‐FRET sensing mechanism which can greatly increase the sensitivity of detection.     

A highly sensitive DNA-AIEgen-based “turn-on” fluorescence chemosensor for amplification analysis of Hg<Superscript>2+</Superscript> ions in real samples and living cells

Functional nucleic acids (FNAs)-based biosensors have shown great potential in heavy metal ions detection due to their low-cost and easy to operate merits. However, in most FNAs based fluorescence probes, the ingenious designs of double-labeled (fluorophore and quencher group) DNA sequence, not only bring the annoyance of organic synthesis, but also restrict its use as a robust biosensor in practical duties. In this paper, we design a simple AIEgens functional nucleic acids (AFNAs) probe which consists of only fluorogen but no quencher group. With the help of duplex-specific nuclease (DSN) enzyme based target recycling, high fluorescence signal and superior sensitivity towards Hg²⁺ are achieved. This robust assay allows for sensitive and selective detection of Hg²⁺ in real water samples and mapping of intracellular Hg²⁺, without double-labeling of oligonucleotide with a dye-quencher pair, nor the multiple assay steps.     

健那绿B的荧光猝灭研究及作为核酸测定探针的应用

用紫外可见光谱、稳态荧光发射及荧光寿命测定研究了核酸猝灭十二烷基磺酸钠胶束中的健那绿荧光。水溶液中弱的健那绿荧光在十二烷基磺酸钠胶束中被大大加强，其最大发射从425纳米移至410纳米，核酸的加入将猝灭健那绿的荧光，当健那绿浓度为2.5×10^–5 mol•L^-1时，荧光猝灭(F₀/F)分别与小牛胸腺DNA及鱼精DNA在2.4×10^–8 到 1.08×10^–7及 1.9×10^–8 到 3.8×10^–8 mol•L^-1范围内成正比, 检测限分别为1.3×10^–8 mol•L^-1 (小牛胸腺DNA)及6.3×10^–9 mol•L^-1 (鱼精DNA)。当DNA浓度较高时, 将系统偏离Stern-Volmer方程。这是因为动态猝灭和静态猝灭同时存在。方法已应用于鸡血提取液中DNA的测定, 测定结果与紫外法一致。