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Reference Module in Chemistry, Molecular Sciences and Chemical Engineering || Deposition, Ligand Removal, and Applications of Atomically Precise, Chemically Synthesized Clusters on Metal Oxide Surfaces
摘要： It is now well established that the properties of metal particles can undergo dramatic changes in properties when they are reduced to the nanometer size regime. It is furthermore evident that these property changes become even more marked below 2 nm, into the nonscalar size regime. Such ultra-small “metal clusters” (also called “nanoclusters”) exhibit dynamic ?uxionality; thus they can barely be de?ned by one single shape. Moreover, their properties are observed to change with the addition or removal of just a single atom. These dramatic changes with cluster size arise because of the molecular-like energy levels present. These energy levels can not only affect the physical properties of the cluster but also its chemical reactivity and so there is a great expectation emerging that metal clusters could act as super-ef?cient catalysts.
关键词： light-emitting diodes,photocatalysis,nanoclusters,catalysis,metal clusters,photovoltaics,sensors
更新于2025-09-10 09:29:36
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Streptavidin-conjugated gold nanoclusters as ultrasensitive fluorescent sensors for early diagnosis of HIV infection
摘要： We have engineered streptavidin-labeled fluorescent gold nanoclusters to develop a gold nanocluster immunoassay (GNCIA) for the early and sensitive detection of HIV infection. We performed computational simulations on the mechanism of interaction between the nanoclusters and the streptavidin protein via in silico studies and showed that gold nanoclusters enhance the binding to the protein, by enhancing interaction between the Au atoms and the specific active site residues, compared to other metal nanoclusters. We also evaluated the role of glutathione conjugation in binding to gold nanoclusters with streptavidin. As proof of concept, GNCIA achieved a sensitivity limit of detection of HIV-1 p24 antigen in clinical specimens of 5 pg/ml, with a detection range up to1000 pg/ml in a linear dose-dependent manner. GNCIA demonstrated a threefold higher sensitivity and specificity compared to enzyme-linked immunosorbent assay for the detection of HIV p24 antigen. The specificity of the immunoassay was 100% when tested with plasma samples negative for HIV-1 p24 antigen and positive for viruses such as hepatitis B virus, hepatitis C virus, and dengue. GNCIA could be developed into a universal labeling technology using the relevant capture and detector antibodies for the specific detection of antigens of various pathogens in the future.
关键词： HIV infection,immunoassay,gold nanoclusters,early diagnosis,fluorescent sensors
更新于2025-09-10 09:29:36
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Sensitive fluorescence sensor for point-of-care detection of trypsin using glutathione-stabilized gold nanoclusters
摘要： There is an urgent demand for on-site detection of biomarker, particularly in clinical diagnosis and therapeutics applications. Herein, we designed a convenient and sensitive fluorescence nanosensor for point-of-care determination of trypsin (TRY). The fluorescence intensity of gold nanoclusters (AuNCs) can be quenched by cytochrome c (Cyt c) via electron transfer mechanism. TRY specifically catalyzes the hydrolysis of Cyt c to produce small peptide fragments, inducing the significant fluorescence recovery. As a result, the AuNCs-based system processed a sensitive and selective response to TRY with the range 0.2-100 μg mL-1, accompanying a detection limit of 0.08 μg mL-1. Significantly, the sensing assay can be used to construct test strips for rapid and visual recognition of TRY. Combining with smartphone and ImageJ software, we further developed an image processing algorithm for quantitative detection of TRY with highly promising, which validated the potential point-of-care application.
关键词： Gold nanoclusters,Fluorescence,Electron transfer,Trypsin,Test strips
更新于2025-09-10 09:29:36
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Fluorescent Neoglycoprotein Gold Nanoclusters: Synthesis and Applications in Plant Lectin Sensing and Cell Imaging
摘要： Carbohydrate-protein interactions mediate fundamental biological processes, such as fertilization, cell signaling, or host-pathogen communication. However, because of the enormous complexity of glycan recognition events, new tools enabling their analysis or applications emerge in recent years. Here, we describe the first preparation of neoglycoprotein functionalized fluorescent gold nanoclusters, containing a biantennary N-glycan G0 as targeting molecule, ovalbumin as carrier/model antigen, and a fluorescent gold core as imaging probe (G0-OVA-AuNCs). Subsequently, we demonstrate the utility of generated G0-OVA-AuNCs for specific sensing of plant lectins and in vitro imaging of dendritic cells.
关键词： Gold nanoclusters,Dendritic cells,Targeting,Neoglycoproteins,Lectin sensing,Carbohydrate-protein interactions
更新于2025-09-10 09:29:36
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Isomeric Effect of Mercaptobenzoic Acids on the Synthesis, Stability, and Optical Properties of Au <sub/>25</sub> (MBA) <sub/>18</sub> Nanoclusters
摘要： We report a simple size focusing, two-step “bottom-up” protocol to prepare water-soluble Au25(MBA)18 nanoclusters, using the three isomers of mercaptobenzoic acids (p/m/o-MBA) as capping ligands and Me3NBH3 as a mild reducing agent. The relative stability of the gas-phase multiply deprotonated Au25(MBA)18 ions was investigated by collision-induced dissociation. This permitted us to evaluate the possible isomeric effect on the Au?S interfacial bond stress. We also investigated their optical properties. The absorption spectra of Au25(MBA)18 isomers were very similar and showed bands at 690, 470, and 430 nm. For all Au25(MBA)18 isomeric clusters, no measurable one-photon excited fluorescence under UV?vis light was found, in neither solid- nor solution-state. The two-photon excited emission spectra and first hyperpolarizabilities of the clusters were also determined. The results are discussed in terms of the possible isomeric effect on excitations within the metal core and the possibility of charge transfer excitations from the ligands to the metal nanocluster.
关键词： Au25(MBA)18 nanoclusters,first hyperpolarizabilities,collision-induced dissociation,isomeric effect,optical properties,two-photon excited emission,mercaptobenzoic acids
更新于2025-09-10 09:29:36
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Synthesis of luminescent gold nanoclusters embedded goose feathers for facile preparation of Au(I) complexes with aggregation-induced emission
摘要： A new kind of luminescent hybrid materials based on ultra-small nanomaterials, i.e., gold nanoclusters (AuNCs) and goose feathers, precious gifts from nature, has been successfully synthesized. Goose feathers possess high specific surface area due to their hierarchical structure and are mainly composed of thiol-rich proteins, e.g., keratin, which can reduce Au(III) and encapsulate the formed AuNCs in a large scale. The resultant golden feathers exhibit bright red luminescence under UV light, of which the substructures, i.e., barbs and barbules, have been sufficiently stained with red-emitting AuNCs. Furthermore, the AuNC-stained feathers maintain almost unchanged structure (solid and hierarchical) and intact chemical composition. The features of such AuNC/feather hybrids, e.g., bulk, high specific surface, inspired us to develop a facile method to prepare various valuable debris from AuNC-based etching, i.e., Au(I) complexes with aggregation-induced emission (AIE). We selected tris(2-carboxyethyl)phosphine and cysteamine as etchants, respectively, which have been previously reported to be able to synthesize AIE-featured Au(I) complexes through etching AuNCs protected by soluble protein. Conveniently, in this approach, the protein-free Au(I) complexes in solution can be attained simply by taking out with bare hand. After adding cation aggregation inducer, e.g., Cd2+, the non-emitting solution can generate bright luminescence, demonstrating the feasibility to synthesize the precious AIE-type Au(I) complexes. This study not only boosts the development of luminescent gold materials through rational use of natural product, enriching the library of gold nanomaterials, but also definitely provides a new view of nanoclusters as reagents to prepare other noble materials.
关键词： Aggregation induced emission,Gold nanoclusters,Chemical etching,Gold(I) complexes,Goose feathers
更新于2025-09-10 09:29:36
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Label-free detection of folic acid using a sensitive fluorescent probe based on ovalbumin stabilized copper nanoclusters
摘要： In this work, ovalbumin (OVA) stabilized copper nanoclusters (OVA-Cu NCs) were prepared through a simple protein-stabilized synthetic method and applied for the sensitive determination of FA. Cu2+ ions were directly reduced to Cu (0) by a mild reducing agent, N2H4·H2O, at room temperature without any other complicated procedure such as adjusting pH and controlling the temperature of the reaction mixture. The as-prepared OVA-Cu NCs showed good chemical stability, wonderful water solubility and excellent biocompatibility. The OVA-Cu NCs were obtained with an average particle size of 2.0 nm and good dispersibility in aqueous solution. They also showed strong red emitting at 625 nm with a quantum yield of 3.95%. The OVA-Cu NCs were then applied for label-free detection of FA based on a static quenching mechanism. The linear calibration curve of detecting FA served from 0.5 μM -200 μM with the detection limit of 0.18 μM. In addition, the developed method was also successfully applied to determine the content of FA in tablet, spinach, orange juice and biological samples with quantitative spike recoveries from 96.9% to 100.9%. For these reasons, the developed OVA-Cu NCs-based fluorescent strategy can thus offer a convenient label-free biosensor platform for the detection of FA in biomedical applications.
关键词： label-free detection,folic acid,red emitting,copper nanoclusters
更新于2025-09-09 09:28:46
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Detection of Various Biomarkers and Enzymes via Nanocluster-Based Fluorescence Turn-On Sensing Platform
摘要： The profiling of disease-related biomarkers is an essential procedure for the accurate diagnosis and intervention of metabolic disorders. Therefore, the development of ultrasensitive and highly selective fluorogenic biosensors for diverse biomarkers is extremely desirable. There is still a considerable challenge to prepare nanocluster-based fluorescence turn-on probes capable of recognizing multiple biomolecules. We herein provide a novel nanocluster-based chemical information processing system (CIPS) for the programmable detecting various metabolites and enzymes. This CIPS consists of the biocatalytic reactions between substrates and their respective oxidases to generate H2O2, which was then employed to synthesize bright fluorescent silver nanoclusters (Ag NCs). Utilizing this system, we are able to accurately probe a series of substrates/ corresponding oxidases with high sensitivity and specificity, including glucose/ glucose oxidase, uric acid/ uric acid oxidase, sarcosine/ sarcosine oxidase, choline/ choline oxidase, xanthine/ xanthine oxidase, and lactic acid/ lactic acid oxidase. Furthermore, this metabolite profiling CIPS can integrate with binary logic operations, which create an intelligently tool for the high throughput screening of various diseases in vitro (e.g., diabetes, gout, prostate cancer, cardiovascular disease, and lactic acidosis).
关键词： nanocluster-based fluorescence turn-on sensing platform,silver nanoclusters,chemical information processing system,biomarkers,enzymes
更新于2025-09-09 09:28:46
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Effects of Rare-Gas Matrices on the Optical Response of Silver Nanoclusters
摘要： The optical response of silver clusters, Agn with n = 8, 20, 35, 58, 92, embedded in a rare-gas matrix are calculated in the framework of the Time-Dependent Density Functional Theory (TDDFT). We present a methodology able to reproduce with unprecedented accuracy the experimental spectra measured on metal clusters embedded in neon, argon, krypton and xenon solid matrices. In our approach, the metal cluster is surrounded by explicit rare-gas atoms and embedded in a polarizable continuum medium. Interactions with the surrounding medium affects both the position and the width of the surface plasmon absorption band of metal clusters. The size dependent shift of the surface plasmon band is evaluated in the case of a neon matrix. While the band shifts to lower energies (red shift) for large clusters, it shifts to higher energies (blue shift) for very small clusters.
关键词： Silver Nanoclusters,Optical,TDDFT,Plasmonics,Magnetic,Hybrid Materials,Rare-Gas Matrices
更新于2025-09-09 09:28:46
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Atomic-Level Doping of Metal Clusters
摘要： Atomically precise noble metal (mainly silver and gold) nanoclusters are an emerging category of promising functional materials for future applications in energy, sensing, catalysis, and nanoelectronics. These nanoclusters are protected by ligands such as thiols, phosphines, and hydride and have sizes between those of atoms and plasmonic nanoparticles. In metallurgy, the properties of a pure metal are modified by the addition of other metals, which often offers augmented characteristics, making them more utilizable for real-life applications. In this Account, we discuss how the incorporation of various metal atoms into existing protected nanoclusters tunes their structure and properties. The process of incorporating metals into an existing cluster is known as doping; the product is known as a doped cluster, and the incorporated metal atom is called a dopant/foreign atom. We first present a brief historical overview of protected clusters and the need for doping and explain (with examples) the difference between an “alloy” and a “doped” cluster, which are two frequently confused terms. We then discuss several commonly observed challenges in the synthesis of doped clusters: (i) doping produces a mixture of compositions that prevents the growth of single crystals; (ii) doping with foreign atoms sometimes changes the overall composition and structure of the parent cluster; and (iii) doping beyond a certain number of foreign atoms decomposes the doped cluster. After delineating the challenges, we review a few potential synthetic methods for doped clusters: (i) the co-reduction method, (ii) the galvanic exchange method, (iii) ligand-induced conversion of bimetallic clusters to doped clusters, and (iv) intercluster reactions. As a foreign atom is able to occupy different positions within the structure of the parent cluster, we examine the structural relationship between the parent clusters and their different foreign-atom-doped clusters. We then show how doping enhances the stability, luminescence, and catalytic properties of clusters. The enhancement factor highly depends on the number and nature of the foreign atoms, which can also alter the charge state of the parent cluster. Atomic-level doping of foreign atoms in the parent cluster is confirmed by high-resolution electrospray ionization and matrix-assisted laser desorption ionization mass spectrometry techniques and single-crystal X-ray diffraction methods. The photophysical properties of the doped clusters are investigated using both time-dependent and steady-state luminescence and optical absorption spectroscopies. After presenting an overview of atomic-level doping in metal clusters and demonstrating its importance for enriching the chemistry and photophysics of clusters and extending their applications, we conclude this Account with a brief perspective on the field’s future.
关键词： applications,doping,properties,atomically precise,noble metal nanoclusters,alloy,synthesis,structure
更新于2025-09-09 09:28:46