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gold nanocluster

Dongqin Yang, Minchuan Luo, Junwei Di, Yifeng Tu, Jilin Yan
A method is described for ratiometric fluorometric assays of H2 O2  by using two probes that have distinct response profiles. Under the catalytic action of ferrous ion, the 615 nm emission of protein-stabilized gold nanoclusters (under 365 nm photoexcitation) is quenched by H2 O2 , while an increased signal is generated with a peak at 450 nm by oxidizing coumarin with the H2 O2 /Fe(II) system to form a blue emitting fluorophore. These decrease/increase responses give a ratiometric signal. The ratio of the fluorescences at the two peaks are linearly related to the concentration of H2 O2 in the range from 0...
May 18, 2018: Mikrochimica Acta
Yuanyuan Li, Xue Hu, Xiaodan Zhang, Haiyan Cao, Yuming Huang
Contrary to organic solvent-induced aggregation of Au nanoclusters (AuNCs), herein, we reported aggregation induced emission enhancement (AIEE) of AuNCs in an aqueous media through confinement of AuNCs by in situ formed Zn-MOF for detecting Zn2+ . Glutathione capped AuNCs (GSH-AuNCs) was synthesized through reduction of Au3+ by glutathione. Zn2+ could significantly enhance the fluorescence of GSH-AuNCs upon addition of 2-methylimidazole, which was attributed to the formation of Zn-MOF. XRD and TEM were used to characterize the in situ formed Zn-MOF...
September 18, 2018: Analytica Chimica Acta
Duyang Gao, Yubin Liu, Yating Wang, Zhen Yuan
Background: Construction of nanoprobes for dual-modal fluorescence/photoacoustic imaging (PAI) is of great importance for the detection of disease pathology and the development of innovative therapeutics. Previously ultra-small gold clusters were designed and used as contrast agents for fluorescence imaging (FLI). However, it is not clear whether they can also serve as promising probes for PAI. In this study, protein-modified ultra-small gold clusters are produced and examined quantitatively as enhanced contrast agents for dual-modal in vivo fluorescence and PAI...
April 2018: Quantitative Imaging in Medicine and Surgery
Zhen Lei, Jiao-Jiao Li, Xian-Kai Wan, Wen-Han Zhang, Quan-Ming Wang
otal structure determination of a ligand-protected gold nanocluster Au144 has been successfully carried out. The title nanocluster has the composition of Au144(C≡CAr)60 (1, Ar = 2-F-C6H4-). Cluster 1 exhibits a quasi-spherical Russian doll-like architecture, comprising a Au54 two-shelled Mackay icosahedron (Au12@Au42), which is further enclosed by a Au60 anti-Mackay icosahedral shell. The Au114 kernel is wrapped by thirty linear ArC≡C-Au-C≡CAr staple motifs. Absorption spectrum of 1 shows two bands at 560 and 620 nm, which is distinctly different from that of thiolated Au144, which was predicted to have an almost identical metal kernel and very similar ligands arrangement in 1...
May 17, 2018: Angewandte Chemie
Ya-Ting Tsu, Yu-Wen Chen
Gold nanocluster has been reported to have high activity and selectivity for various liquid phase hydrogenation reactions. In this study, gold clusters were loaded on various supports, i.e., TiO2, ZnO, Fe2O3, ZrO2, and CeO2. The Au-cluster catalysts were prepared by deposition-precipitation method using HAuCl4 as the precursor. These catalysts were characterized by X-ray diffraction, transmission electron microscopy, and X-ray photoelectron spectroscopy. The catalytic properties of these catalysts were studied in a batch slurry reactor for hydrogenation of p-chloronitrobenzene (p-CNB) at 1...
January 1, 2018: Journal of Nanoscience and Nanotechnology
Mathew T Hembury, Nataliia Beztsinna, Hamed Asadi, Joep van den Dikkenberg, Johannes D Meeldijk, Wim E Hennink, Tina Vermonden
Ultrasmall gold atom clusters (< 2 nm in diameter) or gold nanoclusters exhibit emergent photonic properties (near-infrared absorption and emission) compared to larger plasmonic gold particles, due to the significant quantization of their conduction band. While single gold nanoclusters properties and applications are being increasingly investigated, little is still known about their behaviour and properties when assembled into suprastructures and even less studies are investigating their use for biomedical applications...
May 11, 2018: Biomacromolecules
Jian-Yu Yang, Ting Yang, Xiao-Yan Wang, Ming-Li Chen, Yong-Liang Yu, Jian-Hua Wang
Fluorescent nanoparticles are widely used for sensing biologically significant species. However, it is rarely reported for the discrimination or speciation of metal species. In this work, we report for the first time the speciation of mercury (Hg2+ ) and methylmercury (CH3 Hg+ ) by taking advantage of the fluorescence feature of folic acid-capped gold nanoclusters (FA-AuNCs). FA-Au NCs exhibit an average size of 2.08±0.15 nm and a maximum emission at λex /λem = 280/440 nm with a quantum yield of 27.3%. It is interesting that Hg2+ causes a significant quench on the fluorescence of FA-Au NCs, whereas CH3 Hg+ leads to a remarkable fluorescence enhancement...
May 11, 2018: Analytical Chemistry
Tian Zhao, Patrick J Herbert, Hongjun Zheng, Kenneth L Knappenberger
Electronic carrier dynamics play pivotal roles in the functional properties of nanomaterials. For colloidal metals, the mechanisms and influences of these dynamics are structure dependent. The coherent carrier dynamics of collective plasmon modes for nanoparticles (approximately 2 nm and larger) determine optical amplification factors that are important to applied spectroscopy techniques. In the nanocluster domain (sub-2 nm), carrier coupling to vibrational modes affects photoluminescence yields. The performance of photocatalytic materials featuring both nanoparticles and nanoclusters also depends on the relaxation dynamics of nonequilibrium charge carriers...
May 8, 2018: Accounts of Chemical Research
Yasaman-Sadat Borghei, Morteza Hosseini, Mohammad Reza Ganjali, Huangxian Ju
The authors describe a dual (colorimetric and fluorometric) detection scheme for microRNA. The method is based on the use of fluorescent DNA-modified silver nanoclusters (DNA-AgNCs) and gold nanoparticles (AuNPs). The DNA-AgNCs were linked to AuNPs via the interaction of ssDNA-AgNC probes with AuNPs. This led to quenching of the fluorescence of the DNA-AgNCs (best measured at excitation/emission peaks of 370/450 nm) and also prevents salt-induced aggregation of the AuNPs. Upon addition of microRNA, the DNA on the AgNCs hybridizes with microRNA...
May 8, 2018: Mikrochimica Acta
Shengli Zhuang, Lingwen Liao, Yan Zhao, Jinyun Yuan, Chuanhao Yao, Xu Liu, Jin Li, Haiteng Deng, Jinlong Yang, Zhikun Wu
Metal nanoclusters provide excellent references for understanding metal nanoparticle surfaces, which remain mysterious due to the difficulty of atomically precise characterization. Although some remarkable advances have been achieved for understanding the structure of metal nanoclusters, it is still unknown if the inner kernel-outer staples match is a key-lock match and how the surface staples influence some of the properties of metal nanoclusters. Herein, we have developed an acid-induction method for synthesizing a novel gold nanocluster whose composition is determined to be Au42 (TBBT)26 (TBBT: 4- tert -butylbenzenelthiolate) by ESI-MS and single-crystal X-ray crystallography (SCXC)...
March 7, 2018: Chemical Science
Yuanyuan Hu, Ling Wang, Aixin Song, Jingcheng Hao
The influence of a series of cationic surfactants composed of cetyltrimethylammonium (CTA+) with different counterions (Br-, Cl-, OH-, C7H8O3S-, [CeCl3Br]-, and NO3-) on the ageing process of gold nanoclusters (Au NCs) was studied. The finely different points of Au NCs treated by different surfactants were demonstrated by UV-Vis and fluorescence spectra, TEM images, etc. Due to the difference of counterions, these surfactants have diverse physicochemical properties in surface activity, specific conductivity, pH, and viscosity, which may account for the difference of Au NCs in the ageing process...
May 4, 2018: Langmuir: the ACS Journal of Surfaces and Colloids
Chunlei Zhang, Amin Zhang, Wenxiu Hou, Tianliang Li, Kan Wang, Qian Zhang, Jesús M De La Fuente, Weilin Jin, Daxiang Cui
Biological systems provide the richest spectrum of sophisticated design for materials engineering. We herein provide a paradigm of Au22 (SG)18 -(SG, glutathione thiolate)-engineered and hydrogen bonds engaged assemblies for mimicking capsid protein self-assembly. The water-evaporation-induced self-assembly method allows discrete ultrasmall gold nanoclusters (GNCs) to be self-assembled into super-GNCs assemblies (SGNCs) ranging from nano-, meso- to microscale in water-dimethylsulfoxide binary solvents in a template-free manner...
May 3, 2018: ACS Nano
Magdalena Waszkielewicz, Joanna Olesiak-Banska, Clothilde Comby-Zerbino, Franck Bertorelle, Xavier Dagany, Ashu K Bansal, Muhammad T Sajjad, Ifor D W Samuel, Zeljka Sanader, Miroslawa Rozycka, Magdalena Wojtas, Katarzyna Matczyszyn, Vlasta Bonacic-Koutecky, Rodolphe Antoine, Andrzej Ozyhar, Marek Samoc
Thiolate-protected gold nanoclusters have recently attracted considerable attention due to their size-dependent luminescence characterized by a long lifetime and large Stokes shift. However, the optimization of nanocluster properties such as the luminescence quantum yield is still a challenge. We report here the transformation of Au25Capt18 (Capt labels captopril) nanoclusters occurring at low pH and yielding a product with a much increased luminescence quantum yield which we have identified as Au23Capt17. We applied a simple method of treatment with HCl to accomplish this transformation and we characterized the absorption and emission of the newly created ligated nanoclusters as well as their morphology...
May 1, 2018: Nanoscale
Dinesh Mishra, Vladislav Lobodin, Chengqi Zhang, Fadi Aldeek, Eric Lochner, Hedi Mattoussi
We detail the characterization of atomically precise, luminescent silver and gold bimetallic nanoclusters (Ag and AgAuNCs) grown in the presence of bidentate lipoic acid (LA, the oxidized form) and dihydrolipoic acid (DHLA, the reduced form) ligands. We found that while doping AuNCs with Ag or Cu precursors using up to a 50% molar fraction (during growth) did not lead to any photoluminescence enhancement, doping of AgNCs with Au resulted in a six-fold enhancement of the PL emission compared to undoped AgNCs...
April 30, 2018: Physical Chemistry Chemical Physics: PCCP
Lianzhe Hu, Hong Liao, Lingyan Feng, Min Wang, Wensheng Fu
The peroxidase-like catalytic activity of gold nanoclusters (NCs) is quite low around physiological pH, which greatly limits their biological applications. Herein, we found heparin can greatly accelerate the peroxidase-like activity of Au-NCs at neutral pH. The catalytic activity of Au-NCs toward the peroxidase substrate 3,3',5,5'-tetramethylbenzidine (TMB) oxidation by H2O2 was 25-fold increased in the presence of heparin at pH 7. The addition of heparin not only accelerated the initial catalytic rate of Au-NCs, but also prevented the Au-NCs from catalyst deactivation...
April 26, 2018: Analytical Chemistry
Alvaro Rafael Muñoz-Castro, Jean-Yves Saillard
Exploring the versatility of atomically precise clusters is a relevant issue in the design of functional nanostructures. Superatomic clusters offers an ideal framework to gain further understanding of the different distinctive size-dependent physical and chemical properties. Here, we propose [Au12(SR)6]2- as a minimal 8-electron superatom related to the prototypical [Au25(SR)18]- cluster, depicting half of its core-mass (2.3 kDa vs 5.0 kDa). The [Au12(SMe)6]2- cluster fulfills a 1S2 1P6 electronic configuration, with a distorted tetrahedral Au8 core further viewed as an SP3-hybridized superatom...
April 26, 2018: Chemphyschem: a European Journal of Chemical Physics and Physical Chemistry
Shan-Shan Zhang, Lei Feng, Ravithree D Senanayake, Christine M Aikens, Xing-Po Wang, Quan-Qin Zhao, Chen-Ho Tung, Di Sun
Due to distinctive quantum confinement effects, ultrasmall gold nanoparticles usually exhibit interesting electronic structure and molecular-like properties. However, the lack of atomically-precise structural information makes the understanding of them almost impossible, such as understanding the relationships between their compositions and unique properties. Herein, by reducing a diphosphine AuI precursor (Au2 (dppm)2 Cl2 ; dppm = Ph2 PCH2 PPh2 ) with or without a S2- releasing reagent, we enriched our knowledge of the members in the families of Au13 and Au8 by the structural determinations of two new dppm-protected gold nanoclusters, [Au13 (dppm)6 ]5+ ( SD/Au1 ) and [Au8 (dppm)4 S2 ]2+ ( SD/Au2 ), respectively...
February 7, 2018: Chemical Science
Han-Wen Cheng, Jie Wang, Yong-Jun Li, Jing Li, Shan Yan, Shiyao Shan, Lingyan Wang, Zakiya Skeete, Chuan-Jian Zhong
The ability to harness the optical or electrical properties of nanoscale particles depends on their assembly in terms of size and spatial characteristics which remains challenging due to lack of size focusing. Electrons provide a clean and focusing agent to initiate the assembly of nanoclusters or nanoparticles. Here an intriguing route is demonstrated to lace gold nanoclusters and nanoparticles in string assembly through electron-initiated nucleation and aggregative growth of Au(I)-thiolate motifs on a thin film substrate...
April 17, 2018: Small
Shuaidong Huo, Ying Jiang, Ziwen Jiang, Ryan F Landis, Xing-Jie Liang, Vincent M Rotello
Zwitterions are promising ligands for the fabrication of non-toxic and non-interacting biomaterials. Sulfonamide-based monothiol zwitterionic ligands on gold nanocluster (AuNC) surfaces provide nanomaterials with stable colloidal properties and intense red emission in biological environments. The fluorescence intensity of the nanocluster can be modulated by reactive oxygen species (e.g. ˙OH), allowing for quantitative and selective sensing of antioxidants (e.g. ascorbic acid) in real time.
April 13, 2018: Nanoscale
Yuliang Cheng, Yao Zhang, Renjun Pei, Yunfei Xie, Weirong Yao, Yahui Guo, He Qian
In this work, bismerthiazol was firstly assayed by a fast and portable method employing protein-capping gold nanoculsters as probes. The luminescent intensity of the nanoclusters showed a correlative response towards bismerthiazol from 5 to 4000 μg/mL with a linear relation in the range of 5 - 100 μg/mL. As little as 5 μg/mL of bismerthiazol could be quantified. The high affinity of bismerthiazol to interact with the soybean protein-capped gold nanoclusters contributed to the excellent selectivity of this method over other common pesticides...
2018: Analytical Sciences: the International Journal of the Japan Society for Analytical Chemistry
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