pH调控的变色酸2R稳定的银纳米簇的合成

银纳米簇(Ag NCs)具有特殊的物理和化学性质,其具有广泛的应用前景和研究价值。 本文探索了以变色酸2R为稳定剂,经过两次pH调节构建一种快速制备具有强荧光特性、稳定存在且粒径小的Ag NCs的方法。 在最优实验条件下,运用该方法制备得到的Ag NCs的最大发射波长为450 nm,最大激发波长为336 nm,平均粒径为1.74 nm,主要粒经分布在0.68~2.99 nm区域内,该Ag NCs的晶格间距为0.223 nm,晶格类型为(102)。 该Ag NCs可作为探针应用于溶液中微量重金属离子和非金属离子的测定,小分子、弱酸溶液浓度等方面的检测,也可以用于细胞成像等方面。     

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.     

Recent Progress in Inorganic Anions Templated Silver Nanoclusters: Synthesis,Structures and Properties

Over recent years, research on the ligand‐protected silver clusters have gained significant interest owing to their unique potential applications in catalysis, organic optoelectronics, and luminescent materials. However, the synthesis of structurally precise high‐nuclearity silver nanoclusters is still challenging and become one of the prime interests of chemists. The controllable synthesis of high‐nuclearity silver nanoclusters involves the ingenious use of capping ligands or/and templating agents. Thereinto, the main role of the templating agents is to promote the order arrangement of silver ions around them to form discrete molecules. Our lab has performed comprehensive studies on the ligand‐protected silver clusters in the past eight years. This review highlights recent progress in the use of inorganic template anions, silver precursors, solvents, and the ligand types in synthesizing high‐nuclearity silver nanoclusters. Furthermore, some interesting photo‐ and electrochemical properties revealed by silver clusters including luminescent thermochromism, electrical conductivity, and electrochemical reduction of H₂O₂ have been also summarized.     

Enhanced Emission of Silver Nanoclusters Through Quantitative Phase Transfer

Silver nanoclusters composed of only a few metal atoms present appealing properties such as fluorescence. We have previously reported on aqueous solutions of this fluorophore using poly(methacrylic acid) as scaffold and their sensing properties. Here we report on the preparation of organic solutions of fluorescent silver nanoclusters by quantitative transfer from aqueous solution to an immiscible organic solvent. The fluorescent silver nanoclusters in the organic phase present enhanced emission properties and increased purity, which may expand the range of applications of this promising fluorophore.     

Determination of Thiols by Fluorescence using Au@Ag Nanoclusters as Probes

A simple and label-free fluorescent assay for the sensitive determination of biological thiols was developed using Au@Ag nanoclusters. The sensing approach was based on the strong affinity of thiols to silver on the surface of the nanoclusters. In the presence of thiol-containing amino acids, the fluorescence of the Au@Ag nanoclusters was quenched due to the formation of a non-fluorescent coordination complex via the robust Ag-S bond, which allowed the determination of thiol-containing amino acids in a very simple and rapid way. Under the optimal conditions, an excellent linear relationship was present due to quenching of the Au@Ag nanoclusters over cysteine concentrations between 20 nM and 80 µM with a low detection limit of 5.87 nM. Glutathione was determined between 2 µM and 70 µM with a detection limit of 1.01 µM. In addition, the results reveal that the fluorescent assay has excellent selectivity toward thiol-containing amino acids compared to non-thiol containing amino acids. Moreover, the assay was successfully used to determine cysteine in human plasma, and thus Au@Ag nanoclusters are a suitable fluorescent probe for biological applications.     

富含胞嘧啶单链DNA-银纳米簇荧光探针用于S1核酸酶的灵敏检测

以富含胞嘧啶（C）的单链DNA为模板合成银纳米簇,将其作为功能化探针,建立了一种无标记荧光检测S1核酸酶的方法.S1核酸酶可以特异性识别单链DNA,在最适的酶催化反应条件下,可将其降解为单核苷酸或寡核苷酸片段.当S1核酸酶不存在时,富含C的单链DNA可以有效地合成荧光银纳米簇;当S1核酸酶存在时,单链DNA模板被特异性识别并降解,导致无法形成银纳米簇,使体系荧光信号降低.实验结果表明,银纳米簇的荧光强度随着S1核酸酶浓度的增加而降低.在优化的条件下,体系荧光信号（F/F₀）与S1核酸酶的浓度在5.0×10^-5~4.0×10^-3 U/μL范围内呈线性关系,检出限为2.0×10^-6 U/μL.该荧光探针选择性好,可用于RPMI 1640细胞培养基中S1核酸酶的检测,回收率达到91.8%~109.5%.     

Chiral functionalization of optically inactive monolayer-protected silver nanoclusters by chiral ligand-exchange reactions

We report the ligand-exchange reaction between the optically inactive racemic penicillamine monolayer on a silver nanocluster surface and enantiopure D- or L-penicillamine dissolved in solution. Emergence of the identical band positions in the gel electrophoresis separation assures the presence of size-invariant silver nanoclusters (1.05 and 1.30 nm in core diameter) during the ligand-exchange reaction and allows us to further examine the optical/chiroptical properties of these nanoclusters. Consequently, chiral functionalization of the achiral silver nanoclusters has been demonstrated, yielding large Cotton effects in metal-based electronic transitions with an almost mirror-image relationship between the enantiomeric compounds. The ligand-exchange experiments as well as the normal syntheses of the silver nanoclusters revealed that their absorption profiles and anisotropy factors were strongly dependent on the enantiomeric purity (or enantiomeric excess) of surface chiral penicillamine, so that (several-fold) larger chiroptical responses of the silver nanoclusters as compared to those of the analogous gold clusters with a comparable size could be induced by the metal core deformation or rearrangement along with a universally influential vicinal contribution from the chiral ligand field.     

Synthesis and characterization of colloidal fluorescent silver nanoclusters

Ultrasmall water-soluble silver nanoclusters are synthesized, and their properties are investigated. The silver nanoclusters have high colloidal stability and show fluorescence in the red. This demonstrates that like gold nanoclusters also silver nanoclusters can be fluorescent.     

银纳米粒子簇的设计、 制备和表面增强拉曼光谱

通过匹配激光光斑直径与胶体微球的尺寸, 设计制备了银纳米粒子的表面增强拉曼散射(SERS)基底, 并将其用于研究单个银纳米粒子簇的表面增强拉曼光谱. 在制备纳米粒子的过程中, 考察了等离子体刻蚀时间与银沉积厚度对“单”银纳米粒子结构与形貌的影响. 将吡啶、 巯基苯和罗丹明R6G作为SERS探针分子, 研究了其SERS效应, 通过荧光共振能量转移(FRET)机理, 实现了染料分子在单银纳米粒子簇上的SERS效应. SERS光谱测试与相关计算结果表明, 单个银纳米粒子簇的拉曼增强因子能够达到约10⁶.     

Luminescence of ordered silver iodide nanoclusters inside zeolite host

Ordered silver iodide nanoclusters inside zeolite Y host were prepared by using a thermal diffusion method. The Y-AgI samples were characterized with powder X-ray diffraction, differential thermal analysis, X-ray photoelectron spectroscopy, adsorption technique and chemical analysis. The results show that silver iodide nanoclusters were situated in the ordered cages of the zeolite Y host. The results on the luminescence of the nanocomposites Y-AgI suggest that when the sizes of silver iodide nanoclusters are were very small, non-radiation surface recombination exceeds radiation process and the luminescence efficiency increases as the size of the silver iodide nanoclusters increaseds As the sizes of AgI nanoclusters increased, non-radiative surface recombination effect become equal to the radiation effect of the excitons. As the size of the nanoclusters of AgI in zeolite host further increases, the surface recombination of the nanoclusters becomes a major process.     

铜纳米簇的制备、聚集诱导荧光增强性能及应用研究进展

铜纳米簇不仅具有金属纳米簇的特异性,还有前驱体价格便宜等优点,因此有广泛的应用前景。从配体辅助法、模板法、微波法、电化学法和刻蚀法等综述了铜纳米簇的制备方法。从离子诱导聚集、pH诱导聚集、组装诱导聚集和溶剂诱导聚集增强发射等方面综述了铜纳米簇聚集诱导荧光发射增强性能。从离子检测、小分子检测、酶活性检测、生物大分子检测和生物成像等方面综述了铜纳米簇的应用,并对铜纳米簇的制备、性能优化和应用等方面作了展望。     

Oligonucleotide stabilized silver nanoclusters as fluorescence probe for drug-DNA interaction investigation

In this work, oligonucleotide stabilized silver nanoclusters as novel fluorescent probes were successfully utilized for the drug–DNA interaction study. Silver nanoclusters were proved to be sensitive probes for the drugs investigated (including of two kinds of intercalators, daunorubicin and quinacrine, as well as a non-intercalating binder bisBenzimide H 33258), as the detection limits at 10⁻⁸ mol L⁻¹ level of studied drugs can be achieved. The interactions of drugs and calf thymus DNA were investigated using non-linear fit analysis, and the binding constants as well as binding site sizes were obtained. As biocompatible materials, silver nanoclusters are promising in the chemical especially biochemical analysis fields.     

Site-specific DNA-programmed growth of fluorescent and functional silver nanoclusters

Precise organization of metallic nanoclusters on DNA scaffolds holds great interest for nanopatterned materials that may find uses in electronics, sensors, medicine, and many other fields. Herein, we report the site-specific growth of fluorescent silver nanoclusters by using a mismatched double-stranded DNA template. Few-atom, molecular-scale Ag clusters are found to localize at the mismatched site and the metallized DNA retains its integrity. The DNA-encapsulated nanoclusters can be utilized as functional biological probes to identify single-nucleotide polymorphisms by taking advantage of the very bright fluorescence and excellent photostability of the nanoclusters. This approach offers the possibility of constructing novel DNA-based nanomaterials and nanomechanical devices with more sophisticated functions and will be highly beneficial in future biochemical, pharmaceutical, nanomechanical, and electronic applications.     

Strand exchange reaction modulated fluorescence "off-on" switching of hybridized DNA duplex stabilized silver nanoclusters

The fluorescence (FL)"off-on" switching of designed DNA duplex stabilized silver nanoclusters can be accomplished through the control of DNA strand exchange reaction. The successful sequential control of the FL emission of silver nanoclusters in "off-on" switching cycles confirms that the DNA duplex stabilized silver nanoclusters can work as a new kind of DNA FL switch.     

Early stages in the growth of small silver clusters in aqueous solution

In this mini-review, the growth of silver nanoclusters following the reduction of silver ions in aqueous solution is studied and some clusters are characterized. A model for the molecular structure of trimer silver clusters is discussed as well as the role of aliphatic alcohol radicalsin the growth of silver nanoclusters.     

Protection of Ag Clusters by Metal-Oxo Modules

Monodisperse and atomically precise Ag nanoclusters have attracted considerable recent research interest. A conventional silver cluster usually consists of a silver metallic kernel and an organic peripheral ligand shell. Nevertheless, the present inevitable problem is the unsatisfied stability of such nanoclusters. In this concept, we will give an introduction to Ag clusters protected by metal-oxo modules, which exhibit enhanced stability and unique properties. Accordingly, three different types of clusters are summarized: (1) Ag clusters protected by mononuclear oxometallates; (2) Ag clusters protected by block-like metal-oxo clusters; (3) Ag clusters protected by hollow-like metal-oxo clusters. The aim of this concept is to offer possible general guidance and insight into future rational design of more metal-oxo clusters protected silver clusters or even other coinage metal nanoclusters.     

高核Ag/S纳米团簇合成的研究进展

硫醇配体保护的高核银纳米团簇具有丰富的结构和性能, 在光致发光、 生物传感、 纳米材料等方面具有广阔的应用前景. 然而, 精确控制高核Ag/S纳米团簇的尺寸和结构面临着巨大的挑战, 构建高核Ag/S纳米团簇的可行策略也一直是人们关注的焦点. 近年来, 随着合成方法和表征技术的不断发展, 高核Ag/S纳米团簇的合成和性能研究方面均取得了显著的成就. 本文总结了含20个或以上Ag原子的Ag/S纳米团簇的合成方法(直接还原法、 阴离子模板法及配体交换法), 对部分高核Ag/S纳米团簇的结构进行了探讨, 并展望了未来研究的趋势.     

二氧化硅纳米颗粒表面原位还原银纳米簇电化学发光传感界面的构建与分子识别

通过牛血清蛋白(BSA)对二氧化硅纳米颗粒(SiO₂ NPs)表面进行氨基、 巯基功能化, 随后以BSA同时作为模板和还原剂, 原位生成银纳米簇(Ag NCs), 获得显著增强阴极电化学发光(ECL)信号的Ag NCs-SiO₂ NPs复合纳米材料. 结果表明, 当测试溶液中含有L-半胱氨酸(L-Cys)时, 其与传感界面上的Ag NCs发生共价结合作用, 从而猝灭其ECL信号. 基于该原理, 构建了“开-关”型ECL信号响应模式的L-Cys生物传感器. 该传感器检测L-Cys的浓度范围为50 nmol/L~50 μmol/L, 最低检测限达到13.7 nmol/L, 能够实现L-Cys的高灵敏及特异性分析, 有望在生物、 医学等领域得到广泛应用.     

Electrochemical detection of DNA hybridization based on DNA-templated assembly of silver cluster

The growth of metals on DNA templates has generated considerable interest in connection to the design of metallic nanostructures. Here we exploit the DNA-induced generation of metal clusters for developing an electrical biosensing protocol. The new hybridization assay employs a probe-modified gold surface, and is based on the electrostatic ‘collection’ of silver cations along the DNA duplex, the reductive formation of silver nanoclusters along the DNA backbone, dissolution of the silver aggregate and stripping potentiometric detection of the dissolved silver at a thick-film carbon electrode. The new protocol thus combines the inherent signal amplification of stripping analysis with effective discrimination against nonhybridized DNA.