基于末端脱氧核苷酸转移酶扩增DNA-铜纳米簇荧光传感检测L-组氨酸

利用末端脱氧核苷酸转移酶(TdT)扩增形成聚胸腺嘧啶(T)DNA模板,制备了聚T铜纳米簇(TS-CuNCs),构建了一种用于L-组氨酸(L-His)检测的荧光传感分析新方法.TdT酶在dTTP存在下合成聚T单链DNA核苷酸序列.由于胸腺嘧啶和Cu2+之间的亲合力,聚T单链DNA作为合成铜纳米簇(CuNCs)的模板,加入还原剂后形成CuNCs,荧光强度增强.在L-His存在下,L-组氨酸的咪唑基与Cu2+螯合形成L-His-Cu2+配合物,因而进入聚胸腺嘧啶序列中的Cu2+量减少,使得合成的CuNCs数量减少,导致荧光信号减弱.实验结果表明,体系荧光响应信号与L-His浓度的对数值在5.0×10-9~5.0×10-4 mol/L范围内呈线性关系,检出限达到3.4×10-9 mol/L.本方法用于实际尿液样品中L-组氨酸检测的回收率为97.4%~104.6%,在生物医学及临床诊断中具有潜在应用价值.     

基于铜/银纳米簇检测铜离子的方法研究

通过设计不同富含G碱基的DNA序列,探究了G碱基对核酸-铜/银纳米簇(DNA-Cu/AgNCs)的荧光增强效应,并建立了铜离子的荧光检测方法。结果发现,在富含C碱基序列模板的5'端增加G5序列后,制备得到的铜/银纳米簇的荧光强度显著增强。同时,该DNA-Cu/AgNCs的荧光可被Cu~(2+)和Hg~(2+)猝灭。通过NaBH_4掩蔽Hg~(2+)实现了对Cu~(2+)的特异性检测。该方法检测Cu~(2+)的线性范围为0.01～5.0μmol/L,检出限为5.0 nmol/L。方法具有简单快速、选择性高、成本低等优点,可用于实际样品测定。     

双链铜纳米簇用于铅离子的超灵敏非标记检测

利用聚AT-TA的双链DNA为模板合成铜纳米簇,并作为荧光探针开发了一种荧光生物传感方法用于铅离子的检测。该方法设计是基于铅离子能有效地猝灭铜纳米簇的荧光,当有铅离子存在时,铜纳米簇的荧光强度减弱从而实现对铅离子的灵敏检测。方法用于铅离子的检测,检测时间只需15 min,检出限为5.2 pmol/L,特异性好(没有其它金属离子的干扰)。     

水溶性碳纳米粒子的制备及其在DNA和单核苷酸多态性分析中的应用

利用电化学氧化的方法制备了水溶性好、粒径为7～12nm的碳纳米粒子,该碳纳米粒子通过π-π相互作用吸附荧光标记的单链DNA探针,并能有效地猝灭其荧光．当单链DNA探针与匹配的DNA目标分子杂交形成双链DNA时,猝灭的荧光被恢复,由此可以检测1-200nmol／L的DNA目标分子。此外,在碳纳米粒子存在时,由荧光标记的DNA探针和DNA目标分子形成的双链DNA的熔解温度可以简便地被测定,当双链DNA有错配碱基时,其熔解温度降低,由此可方便、快速地分析单核苷酸多态性．     

基于金纳米簇探针的荧光猝灭检测铁离子

以D-色氨酸为保护剂和还原剂, 采用水热法快速制备了具有强荧光的金纳米簇(D-Trp@AuNCs); 以其作为荧光探针, 建立了基于荧光猝灭的选择性高灵敏检测Fe³⁺的传感方法. 利用透射电子显微镜(TEM)、 紫外-可见光谱(UV-Vis)和红外光谱(IR)等手段对制备的金纳米簇进行了表征, 并利用荧光光谱研究了D-Trp@AuNCs的荧光性能. 结果表明, D-Trp@AuNCs具有较好的生物相容性, 其最大激发波长为370 nm, 最大发射波长为460 nm; 向金纳米簇溶液中加入Fe³⁺后, D-Trp@AuNCs的荧光发生明显猝灭, 其猝灭程度与Fe³⁺的浓度在0.3~500.0 μmol/L范围内呈现良好的线性关系, 检出限为33.1 nmol/L(S/N=3). 将该荧光探针用于实际水样中Fe³⁺的检测, 回收率为86.6%~106.5%.     

阳离子荧光共轭聚合物结合纳米颗粒用于DNA检测

利用纳米颗粒对目标DNA的富集、分离作用以及阳离子荧光共轭聚合物良好的荧光特性,建立了一种特异性检测DNA的新方法.首先将标记有猝灭基团的DNA捕获探针修饰到纳米颗粒上,捕获互补的DNA分子;然后加入S1核酸酶,除去未捕获到互补DNA的捕获探针;最后用Dnase Ⅰ将颗粒上的双链切断,使猝灭基团从纳米颗粒上解离下来,与阳离子荧光共轭聚合物结合并猝灭其荧光.结果表明,目标核酸的浓度与该聚合物的荧光猝灭程度正相关,且具有良好的特异性,线性响应范围为5.0～40 nmol/L; 检出限为3.7 nmol/L(S/N=3).     

一步法合成D-青霉胺稳定的铜纳米团簇 用于ClO-的检测

以D-青霉胺为还原剂和保护剂通过化学还原一步法合成铜纳米团簇(Cu NCs)。采用TEM和XPS对铜纳米团簇的结构进行表征,通过荧光光谱对铜纳米团簇的光学特性进行分析。该铜纳米团簇具有很好的稳定性。在探究该铜纳米团簇的应用方面,实验结果表明:ClO~-能够有效地猝灭铜纳米团簇的荧光。在ClO~-浓度范围1-9 mM时,荧光强度(F_0-F)/F_0与ClO~-的浓度呈线性关系,检出限为2 mM。因此,该铜纳米团簇可以高选择性、高灵敏度地识别并检测ClO~-。该方法用于实际水样中ClO~-的检测,精密度、重现性和准确性均较好,可作为测定水中ClO~-含量的快速检测方法。     

寡聚核苷酸稳定银纳米簇荧光探针的合成及含巯基药物的高选择性分析测定

金属纳米团簇具有很好的光电特性,但因其化学活性高而不易稳定存在于水介质中.根据核苷酸的所有碱基中胞嘧啶与Ag+的结合能力最强,寡聚鸟苷酸易折叠和序列中同时存在腺嘌呤和胸腺嘧啶易发生杂交导致自身团聚等因素,本文设计了胞嘧啶和腺嘌呤各占50%的寡聚核苷酸序列模板分子用于合成稳定性好、荧光性能优异的银纳米簇,并进一步应用于含巯基药物的分析测定.研究表明,含巯基药物通过巯基能高选择性地与银纳米簇发生相互作用形成Ag?S键,使得银纳米簇的荧光发生静态猝灭.据此,本文建立了以抗高血压药物卡托普利为代表的含巯基物质的分析方法.该方法快速、准确、选择性好、灵敏度高,可成功应用于卡托普利片剂的分析.     

银纳米簇荧光探针测定水样中铜(Ⅱ)

制备了银纳米簇并考察其光学性能,最大吸收波长和荧光激发波长均在340 nm,荧光发射波长为462 nm。Cu2+可使银纳米簇的荧光发生明显猝灭,且其它金属离子干扰较小。依据Cu2+银纳米簇荧光强度猝灭率与Cu2+的相关性,建立了Cu2+测定方法,采用4参数S曲线方程拟合,对Cu2+检出限为0.1μmol/L。方法用于水样中Cu2+检测,可以满足环境水样中Cu2+的检测要求。     

基于对荧光铜纳米簇合成的抑制检测三聚氰胺

三聚氰胺能与铜离子(Cu2+)形成配合物,对荧光铜纳米簇的合成有明显抑制作用,且其抑制程度与三聚氰胺浓度在一定范围内呈线性关系.基于此构建了一种简单、快速检测三聚氰胺的方法.以聚T单链DNA为模板合成的铜纳米簇作为荧光探针,当三聚氰胺存在时,Cu2+与三聚氰胺生成配合物,阻碍铜纳米簇的合成,导致荧光强度降低.在优化的实验条件下,三聚氰胺浓度在5~120 μmol/L范围内呈良好的线性关系,检出限为1.5 μmol/L,牛奶样品中三聚氰胺加标回收率为96.3%~104.4%.与传统纳米金/银、量子点等方法相比,本方法具有简单、快速、灵敏等优点.     

基于铜纳米簇的聚集诱导发光检测铅离子

基于谷胱甘肽保护的非贵金属铜纳米簇(Cu NCs@GSH)的聚集诱导发光现象,建立了快速检测铅离子(Pb2+)的“Turn on”型荧光分析方法.Cu NCs@GSH溶液荧光强度很弱,当存在pb2+时,荧光强度可显著增强,溶液显示明亮的橙黄色.基于此原理建立了检测pb2+的荧光方法,线性范围为200～700 μmol/L,检出限为106 μmol/L,常见金属离子不干扰pb2+的测定.本方法简单快速、选择性高,可实现对pb2+的可视化定性检测.     

聚胸腺嘧啶单链DNA-CuNCs荧光增强法用于汞离子的高灵敏检测

基于Hg~(2+)与DNA中胸腺嘧啶(T)结合的高度特异性和DNA铜纳米簇的荧光增强性质,构建了一种简便、灵敏检测汞离子的新方法.当Hg~(2+)存在时,聚T单链DNA(P1)通过T-Hg~(2+)-T特异性结合形成双链DNA,Cu~(2+)经抗坏血酸钠还原后生成的中间体Cu+与双链DNA螺旋结构间的氢键部分有强的结合力,促使Cu0附着聚集在双链DNA上形成铜纳米簇,导致体系荧光增强,从而实现对汞离子的高灵敏检测.体系荧光强度与Hg~(2+)浓度的对数值成正比,对Hg~(2+)检测的线性范围为1.0 nmol/L~10μmol/L,检出限达0.4 nmol/L,对湖水样品中Hg~(2+)检测的回收率达到97.2%~106.6%.与传统方法相比,该方法具有无需标记、检出限低及选择性好等优点,可用于环境水体中汞离子的测定.     

Ultrasensitive fluorescence detection of glutaraldehyde in water samples with bovine serum albumin-Au nanoclusters

Based on the cross-linking nature of BSA in the presence of glutaraldehyde (GA), the fluorescence of BSA-stabilized Au nanoclusters was effectively quenched by GA. A new method for ultrasensitive GA detection in water samples was thus developed with fluorescent BSA-stabilized Au nanoclusters. The fluorescence quenching of BSA-stabilized Au nanoclusters in the presence of GA fitted to Stern-Volmer equation. In the GA concentration range of 0.8–6 μM, a linear relationship of F₀/F versus GA concentration was obtained with a limit of detection (LOD) of 0.2 μM. The relative standard deviation of 5 replicate measurements of 4 μM GA is 1.3%. This method shows good selectivity over other organics in water samples. The feasibility of the new sensor for GA in different water samples was demonstrated.     

聚乙烯吡咯烷酮保护荧光铜纳米团簇制备及其对乙醇的快速准确检测

乙醇含量的精确定量检测对于环境监测、临床诊断、食品检测以及饮用酒水都至关重要。以氯化铜（CuCl₂）为铜源、聚乙烯吡咯烷酮（PVP）为保护剂、2-巯基苯并噻唑（MBT）为稳定剂、抗坏血酸（AA）为还原剂,利用声化学还原法,以绿色简单、快速便捷的手段成功合成出具有橙色荧光的铜纳米团簇（PVP-Cu NCs）。利用紫外可见吸收光谱、荧光光谱、红外光谱、透射电镜和X射线光电子能谱技术研究其结构和性能,发现PVP-Cu NCs的最佳激发波长和发射波长分别为340和580 nm,其平均粒径为6.0 nm。PVP-Cu NCs可通过聚集诱导猝灭机制实现对乙醇的灵敏检测,其荧光强度与乙醇含量在体积分数5%~45%范围内呈现出良好的线性关系,且PVP-Cu NCs可制作成乙醇检测试纸,对乙醇进行可视化检测。     

Fluorescent Determination of Dopamine Using Polythymine-Templated Copper Nanoclusters

ABSTRACT

Dopamine has been shown interact strongly with Cu²⁺ to form a stable complex and inhibit the formation of polythymine-templated copper nanoclusters. Based on these findings, a label-free sensing strategy has been designed for the detection of dopamine using polythymine-templated copper nanoclusters as fluorescence probes. The fluorescent method exhibits sensitive and selective detection of dopamine with a linear range from 1?nM to 50?µM and a detection limit of 0.5?nM. In addition, the method was successfully applied for the determination of dopamine in dopamine hydrochloride injection samples. Thus, this approach holds considerable potential for the construction of a simple, rapid, and sensitive fluorescent assay for the determination of dopamine.     

Polyethyleneimine-capped silver nanoclusters as a fluorescence probe for sensitive detection of hydrogen peroxide and glucose

In this work, we utilized polyethyleneimine-capped silver nanoclusters (PEI-Ag nanoclusters) to develop a new fluorometric method for the determination of hydrogen peroxide and glucose with high sensitivity. The PEI-Ag nanoclusters have an average size of 2 nm and show a blue emission at 455 nm. The photostable properties of the PEI-Ag nanoclusters were examined. The fluorescence of the PEI-Ag nanoclusters could be particularly quenched by H₂O₂. The oxidization of glucose by glucose oxidase coupled with the fluorescence quenching of PEI-Ag nanoclusters by H₂O₂ can be used to detect glucose. Under optimum conditions, the fluorescence intensity quenched linearly in the range of 500 nM–100 μM with high sensitivity. The detection limit for H₂O₂ was 400 nM. And a linear correlation was established between fluorescence intensity (F₀ − F) and concentration of glucose in the range of 1.0 × 10⁻⁶ to 1.0 × 10⁻⁵ M and 1.0 × 10⁻⁵ to 1.0 × 10⁻³ M with a detection limit of 8.0 × 10⁻⁷ M. The method was used for the detection of glucose in human serum samples with satisfactory results. Furthermore, the mechanism of sensitive fluorescence quenching response of Ag nanoclusters to glucose and H₂O₂ has been discussed.     

Bovine serum albumin-stabilized gold nanoclusters as a fluorescent probe for determination of ferrous ion in cerebrospinal fluids via the Fenton reaction

Gold nanoclusters (AuNCs) stabilized with bovine serum albumin were utilized as a fluorescent probe for ferrous ion. The detection scheme is based on the quenching of the fluorescence of the modified AuNCs by hydroxyl radical (•OH) that is generated in the Fenton reaction between Fe(II) and H₂O₂. Fe(II) can be quantified in the 0.08 to 100 μM concentration range, and the limit of detection is as low as 24 nM. The method also displays good accuracy and high sensitivity when employed to the determination of Fe(II) in rat cerebrospinal fluids (CSFs). When applied to CSFs of a rat model of Alzheimer’s disease, it revealed enhanced levels of Fe(II) compared to a control, thereby showing the important physiological role of iron(II) in this disease.

BSA-stabilized gold nanoclusters (BSA-AuNCs) were utilized for the determination of ferrous ion in rat cerebrospinal fluids. The method is based on the quenching of the fluorescence by hydroxyl radical (•OH) which is generated in the Fenton reaction between Fe(II) and H₂O₂.

     

The Origin of the Photoluminescence Enhancement of Gold‐Doped Silver Nanoclusters: The Importance of Relativistic Effects and Heteronuclear Gold–Silver Bonds

The weak photoluminescence of silver nanoclusters prevents their broad application as luminescent nanomaterials. Recent experiments, however, have shown that gold doping can significantly enhance the photoluminescence intensity of Ag₂₉ nanoclusters but the molecular and physical origins of this effect remain unknown. Therefore, we have computationally explored the geometric and electronic structures of Ag₂₉ and gold‐doped Ag_29?xAu_x (x=1–5) nanoclusters in the S₀ and S₁ states. We found that 1) relativistic effects that are mainly due to the Au atoms play an important role in enhancing the fluorescence intensity, especially for highly doped Ag₂₆Au₃, Ag₂₅Au₄, and Ag₂₄Au₅, and that 2) heteronuclear Au?Ag bonds can increase the stability and regulate the fluorescence intensity of isomers of these gold‐doped nanoclusters. These novel findings could help design doped silver nanoclusters with excellent luminescence properties.     

Sensitive signal-on fluorescent sensing for copper ions based on the polyethyleneimine-capped silver nanoclusters–cysteine system

In this work, we present a label-free sensor for copper ions. This sensor is composed of silver nanoclusters and cysteine. The fluorescence of the silver nanoclusters was quenched by cysteine, which was recovered in the presence of copper ions. This binding of silver nanoclusters to cysteine promoted agglomeration of silver nanoclusters to yield larger non-fluorescent silver nanoparticles. The presence of copper ions resulted in the oxidation of cysteine to form a disulfide compound, leading to recovery of fluorescence of the silver nanoclusters. The fluorescence of the silver nanoclusters in the presence of cysteine increased with increasing concentration of copper ions in the range of 10–200 nM. The detection limit of this sensor for copper ions was 2.3 nM. The silver nanoclusters–cysteine sensor provides a simple, cost-effective, and sensitive platform for the detection of copper ions.