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gold nanocluster

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https://www.readbyqxmd.com/read/29136363/dynamic-stabilization-of-the-ligand-metal-interface-in-atomically-precise-gold-nanoclusters-au68-and-au144-protected-by-meta-mercaptobenzoic-acid
#1
Tiia-Riikka Tero, Sami Malola, Benedek Koncz, Emmi Pohjolainen, Saara Lautala, Satu Mustalahti, Perttu Permi, Gerrit Groenhof, Mika Pettersson, Hannu Häkkinen
Ligand-stabilized, atomically precise gold nanoclusters with a metal core of a uniform size of just 1 - 3 nm constitute an interesting class of nanomaterials with versatile possibilities for applications due to their size dependent properties and modifiable ligand layers. The key to extending the usability of the clusters in applications is to understand the chemical bonding in the ligand layer as a function of cluster size and ligand structure. Previously, it has been shown that monodispersed gold nanoclusters, stabilized by meta-mercaptobenzoic acid (m-MBA or 3-MBA) ligands and with sizes of 68 to 144 gold atoms, show ambient stability...
November 14, 2017: ACS Nano
https://www.readbyqxmd.com/read/29136071/gold-nanoclusters-with-a-wide-range-of-fluorescence-characteristics-generated-in-situ-in-polymer-thin-films-potential-gas-sensing-application
#2
U Divya Madhuri, T P Radhakrishnan
Fabrication of gold nanoclusters (GNCs) with tunable fluorescence characteristics inside polymer thin films is attractive from the device application perspective. In this study, GNCs are generated in situ in poly(methyl methacrylate) films exploiting their weak reducing capability with no additional reducing agent, and by short and mild thermal annealing; the chemistry involved is probed through control experiments. The nanoclusters formed with ∼0.5 weight percent of gold are very stable and show appreciable fluorescence emission with a small Stokes shift (∼40 nm); interestingly, blending polystyrene enhances the fluorescence...
November 14, 2017: Dalton Transactions: An International Journal of Inorganic Chemistry
https://www.readbyqxmd.com/read/29135045/an-alkynyl-stabilized-pt%C3%A2-ag%C3%A2-%C3%A2-cluster-featuring-two-dimensional-alkynyl-platinum-crucifix-motif
#3
Hui Shen, Tsutomu Mizuta
The "staple motif" has been widely applied to depict and predict the structures of thiolate or alkynyl-protected gold nanoclusters. By contrast, the composition, dimensions, configuration, and functionality of the platinum-ligand motif has remained completely unknown. Herein, we report the synthesis and crystal structure of a novel luminescent Pt₅Ag₂₂(C≡CPh)₃₂ (1) cluster, in which two-dimensional and two-functional alkynyl-platinum "crucifix motif" was observed. Such a crucifix motif with one Pt center and four alkynyl groups in the same plane acts as a two-dimensional unit in the cluster and functions as both a protective cover and an intermediate joint...
November 14, 2017: Chemistry: a European Journal
https://www.readbyqxmd.com/read/29116739/gold-nanocluster-mediated-cellular-death-under-electromagnetic-radiation
#4
Anna Cifuentes-Rius, Angela Ivask, Shreya Das, Nuria Penya Auladell, Laura Fabregas, Nicholas L Fletcher, Zachary H Houston, Kristofer James Thurecht, Nicolas H Voelcker
Gold nanoclusters (Au NCs) have become a promising nanomaterial for cancer therapy due to their biocompatibility and fluorescent properties. In this study, the effect of ultrasmall protein-stabilized 2 nm Au NCs on six types of mammalian cells (fibroblasts, B-lymphocytes, glioblastoma, neuroblastoma, and two types of prostate cancer cells) under electromagnetic radiation is investigated. Cellular association of Au NCs in vitro is concentration-dependent and Au NCs have low intrinsic toxicity. However, when Au NC-incubated cells are exposed to 1 GHz electromagnetic field (microwave radiation, µW), cell viability significantly decreases thus demonstrating that Au NCs exhibit specific µW dependent cytotoxicity, likely resulting from localized heating...
November 8, 2017: ACS Applied Materials & Interfaces
https://www.readbyqxmd.com/read/29115312/plasmonic-support-mediated-activation-of-1-nm-platinum-clusters-for-catalysis
#5
S Wieghold, L Nienhaus, F L Knoller, F F Schweinberger, J J Shepherd, J W Lyding, U Heiz, M Gruebele, F Esch
Nanometer-sized metal clusters are prime candidates for photoactivated catalysis, based on their unique tunable optical and electronic properties, combined with a large surface-to-volume ratio. Due to the very small optical cross sections of such nanoclusters, support-mediated plasmonic activation could potentially make activation more efficient. Our support is a semi-transparent gold film, optimized to work in a back-illumination geometry. It has a surface plasmon resonance excitable in the 510-540 nm wavelength range...
November 8, 2017: Physical Chemistry Chemical Physics: PCCP
https://www.readbyqxmd.com/read/29110468/redox-triggered-bonding-induced-emission-of-thiol-functionalized-gold-nanoclusters-for-luminescence-turn-on-detection-of-molecular-oxygen
#6
Hang Ao, Hui Feng, Mengting Zhao, Meizhi Zhao, Jianrong Chen, Zhaosheng Qian
Most optical sensors for molecular oxygen were developed based on the quenching effect of the luminescence of oxygen-sensitive probes; however, the signal turn-off mode of these probes is undesirable to quantify and visualize molecular oxygen. Herein, we report a novel luminescence turn-on detection strategy for molecular oxygen via the specific oxygen-triggered bonding-induced emission of thiol-functionalized gold nanoclusters. Thiol-functionalized gold nanoclusters were prepared by a facile one-step synthesis, and as-prepared gold nanoclusters possess significant aggregation-induced emission (AIE) property...
November 15, 2017: ACS Sensors
https://www.readbyqxmd.com/read/29105296/bulky-counterions-enhancing-the-two-photon-excited-fluorescence-of-gold-nanoclusters
#7
Franck Bertorelle, Christophe Moulin, Antonin Soleilhac, Clothilde Comby-Zerbino, Philippe Dugourd, Isabelle Russier-Antoine, Pierre-François Brevet, Rodolphe Antoine
Increasing fluorescence quantum yields of ligand-protected gold nanoclusters has attracted wide research interest. The strategy consisting in using bulky counterions has been found to dramatically enhance the fluorescence. In this communication, we push forward this concept to the nonlinear optical regime. We show that by an appropriate choice of bulky counterions and of solvent, a 30-fold increase in two-photon excited fluorescence (TPEF) signal at ~600 nm for gold nanoclusters can be obtained. This would correspond to a TPEF cross section in the range of 0...
November 3, 2017: Chemphyschem: a European Journal of Chemical Physics and Physical Chemistry
https://www.readbyqxmd.com/read/29098757/on-the-non-metallicity-of-2-2-nm-au246-sr-80-nanoclusters
#8
Rongchao Jin, Meng Zhou, Chenjie Zeng, Yongbo Song, Jonathan W Padelford, Gangli Wang, Matthew Y Sfeir, Tatsuya Higaki
The transition from molecular to plasmonic behaviour in metal nanoparticles with increasing size remains a central question in nanoscience. We report that the giant 246-gold-atom nanocluster (2.2 nm in gold core diameter) protected by 80 thiolate ligands is surprisingly non-metallic based on UV-vis and femtosecond transient absorption spectroscopy as well as electrochemical measurements. Specifically, the Au246 nanocluster exhibits multiple excitonic peaks in transient absorption spectra and electron dynamics independent of the pump power, which are in contrast to the behaviour of metallic gold nanoparticles...
November 3, 2017: Angewandte Chemie
https://www.readbyqxmd.com/read/29098339/a-biomimetic-approach-to-conjugate-vitamin-b6-cofactor-with-the-lysozyme-cocooned-fluorescent-auncs-and-its-application-in-turn-on-sensing-of-zinc-ii-in-environmental-and-biological-samples
#9
Shilpa Bothra, Lavanya Thilak Babu, Priyankar Paira, S K Ashok Kumar, Rajender Kumar, Suban K Sahoo
This communication focusses on the synthesis of red fluorescent lysozyme cocooned gold nanoclusters (Lyso-AuNCs) that have been successfully applied for the selective and specific recognition of the vitamin B6 cofactor pyridoxal-5'-phosphate (PLP). The red fluorescence of Lyso-AuNCs showed remarkable color change to yellow upon conjugation with PLP due to the formation of a Schiff base between the free -NH2 present in the lysozyme and the -CHO group of PLP. The developed PLP conjugated Lyso-AuNCs (PLP_Lyso-AuNCs) was applied for the selective turn-on recognition of Zn(2+) ions in aqueous medium...
November 2, 2017: Analytical and Bioanalytical Chemistry
https://www.readbyqxmd.com/read/29094138/synthesis-of-highly-fluorescent-gold-nanoclusters-and-their-use-in-sensitive-analysis-of-metal-ions
#10
Yayu Yang, Ailing Han, Ruixue Li, Guozhen Fang, Jifeng Liu, Shuo Wang
As a promising fluorescent material, gold nanoclusters (Au NCs) have been used for biosensing and imaging. In metal ion sensing, the fluorescence of Au NCs is usually quenched in the presence of ions, but the reaction mechanism has not been clarified. In this work, mercaptan acids (3-mercaptopropanoic acid (3-MPA), 6-mercaptohexanoic acid (6-MHA), 11-mercaptoundecanoic acid (11-MUA) and 16-mercaptohexadecanoic acid (16-MHA)) were used as reductants and ligands to synthesize fluorescent Au NCs. The Au NCs had a core containing 18 atoms capped by 18 (3-MPA) or 10 (6-MHA, 11-MUA, 16-MHA) ligand molecules...
November 2, 2017: Analyst
https://www.readbyqxmd.com/read/29075729/size-dependence-of-gold-clusters-with-precise-numbers-of-atoms-in-aerobic-oxidation-of-d-glucose
#11
Junying Zhang, Zhimin Li, Jiahui Huang, Chao Liu, Feng Hong, Kai Zheng, Gao Li
Size-dependence is an important factor in gold nanocatalysis. In this study, we explored the catalytic performance of atomically precise Aun(PET)m nanocluster catalysts (where, PET = phenylethanethiolate) of different gold atoms and sizes, including Au25(PET)18 (∼1.2 nm), Au38(PET)24 (∼1.5 nm), and Au144(PET)60 (∼1.9 nm) nanoclusters. These Aun(PET)m gold clusters, immobilized on activated carbon (AC) and used as heterogeneous catalysts, were characterized by transmission electron microscope (TEM), BET as well as X-ray photoelectron spectroscopy (XPS)...
November 9, 2017: Nanoscale
https://www.readbyqxmd.com/read/29075509/oligochitosan-stabilized-photoluminescent-gold-nanoconstructs-for-optical-bioimaging
#12
Donghyuck Yoo, Dongwon Lee
BACKGROUND: Gold nanoclusters (AuNCs) are typically composed of several to tens of gold atoms which are stabilized with biomacromolecules such as bovine serum albumin (BSA). Au NCs fluoresces in the visible to near infrared region, in a size-dependent manner. AuNCs solutions have potential as fluorophore in a wide range of biomedical applications such as biodetection, biosensing and bioimaging in vitro and in vivo. However, their stability and harsh condition of preparation limit their biomedical application...
2017: Biomaterials Research
https://www.readbyqxmd.com/read/29039677/two-way-transformation-between-fcc-and-nonfcc-structured-gold-nanoclusters
#13
Hongwei Dong, Lingwen Liao, Zhikun Wu
Precisely tuning the structure of nanomaterials, especially in a two-way style, is challenging but of great importance for regulating properties and for practical applications. The structural transformation from nonfcc to fcc (face center cubic) in gold nanoclusters has been recently reported; however, the reverse process, that is, the structural transformation from fcc to nonfcc, not to mention the two-way structural transformation between fcc and nonfcc, remains unknown. We developed a novel synthesis method, successfully fulfilled the two-way structure transformation, and studied the stability of gold nanoclusters with different structures...
October 19, 2017: Journal of Physical Chemistry Letters
https://www.readbyqxmd.com/read/29034569/gold-doping-of-double-crown-pd-nanoclusters
#14
Zhikun Wu
Double-crown Ni, Pd or Pt nanoclusters have attracted extensive interests due to their aesthetic structure and intriguing properties. However, their doping by other metals remains unknown until now. Herein, we successfully dope Pd4(PET)8 and Pd5(PET)10 (PET: SCH2CH2Ph) with gold and characterize the doped nanoclusters by using multiple techniques such as mass spectrometry and X-ray crystallography. It is revealed that in the doping not one but two gold atoms replace one Pd with the other double-crown structure essentially unchanged, and the gold-doping results in the blue-shift of the maximum visible absorption, the increase of optical energy gap and the reduction of anti-aromaticity of monometal Pd nanoclusters...
October 15, 2017: Chemistry: a European Journal
https://www.readbyqxmd.com/read/29030559/understanding-seed-mediated-growth-of-gold-nanoclusters-at-molecular-level
#15
Qiaofeng Yao, Xun Yuan, Victor Fung, Yong Yu, David Tai Leong, De-En Jiang, Jianping Xie
The continuous development of total synthesis chemistry has allowed many organic and biomolecules to be produced with known synthetic history-that is, a complete set of step reactions in their synthetic routes. Here, we extend such molecular-level precise reaction routes to nanochemistry, particularly to a seed-mediated synthesis of inorganic nanoparticles. By systematically investigating the time-dependent abundance of 35 intermediate species in total, we map out relevant step reactions in a model size growth reaction from molecularly pure Au25 to Au44 nanoparticles...
October 13, 2017: Nature Communications
https://www.readbyqxmd.com/read/29022633/in-site-encapsulating-gold-nanowires-into-hemin-coupled-protein-scaffolds-through-biomimetic-assembly-towards-the-nanocomposites-with-strong-catalysis-electrocatalysis-and-fluorescence-properties
#16
Shuai Li, Liyan Zhang, Yao Jiang, Shuyun Zhu, Xiaoxia Lv, Zhiqiang Duan, Hua Wang
An efficient and green biomimetic assembly protocol was developed for the fabrication of multifunctional nanocomposites by mimicking the configuration of natural protein enzymes. Bovine serum albumin (BSA) as the protein model was first split to produce the disassembled BSA (dBSA) of linear polymer and then coupled with catalytic Hemin (Hem). The yielded dBSA-Hem scaffolds were utilized to in-site encapsulate gold nanoclusters (AuNCs) through biominerization, yielding the dBSA-Hem-AuNCs. It was discovered that the nanocomposites could display the well-defined composition and spheric morphology...
October 26, 2017: Nanoscale
https://www.readbyqxmd.com/read/29019494/relativistic-dft-investigation-of-electronic-structure-effects-arising-from-doping-the-au25-nanocluster-with-transition-metals
#17
Fahri Alkan, Alvaro Muñoz-Castro, Christine M Aikens
We perform a theoretical investigation using density functional theory (DFT) and time-dependent DFT (TDDFT) on the doping of the Au25(SR)18(-1) nanocluster with group IX transition metals (M = cobalt, rhodium and iridium). Different doping motifs, charge states and spin multiplicities were considered for the single-atom doped nanoclusters. Our results show that the interaction (or the lack of interaction) between the d-type energy levels that mainly originate from the dopant atom and the super-atomic levels plays an important role in the energetics, the electronic structure and the optical properties of the doped systems...
October 26, 2017: Nanoscale
https://www.readbyqxmd.com/read/29018847/the-reactivity-of-phenylethanethiolated-gold-nanoparticles-with-acetic-acid
#18
Nan Xia, Zibao Gan, Lingwen Liao, Shengli Zhuang, Zhikun Wu
We report the size-dependent reactivity of phenylethanethiolated gold nanoparticles with acetic acid. Employing this reactivity, we synthesize a novel nanocluster Au38(PET)26 (PET: phenylethanethiolate), which is otherwise difficult to obtain and exhibits remarkably different photoluminescence and electrochemical properties compared with the well-known Au38(PET)24 nanoclusters. And the reaction process between Au38(PET)26 and acetic acid was probed by matrix-assisted laser desorption/ionization time of flight mass spectrometry...
October 24, 2017: Chemical Communications: Chem Comm
https://www.readbyqxmd.com/read/28989966/ligand-effects-in-catalysis-by-atomically-precise-gold-nanoclusters
#19
Xian-Kai Wan, Jia-Qi Wang, Zi-Ang Nan, Quan-Ming Wang
Atomically precise gold nanoclusters are ideal model catalysts with well-defined compositions and tunable structures. Determination of the ligand effect on catalysis requires the use of gold nanoclusters with protecting ligands as the only variable. Two isostructural Au38 nanoclusters, [Au38(L)20(Ph3P)4](2+) (L = alkynyl or thiolate), have been synthesized by a direct reduction method, and they have an unprecedented face-centered cubic (fcc)-type Au34 kernel surrounded by 4 AuL2 staple motifs, 4 Ph3P, and 12 bridging L ligands...
October 2017: Science Advances
https://www.readbyqxmd.com/read/28985680/understanding-the-effect-of-single-cysteine-mutations-on-gold-nanoclusters-as-studied-by-spectroscopy-and-density-functional-theory-modeling
#20
Sayantani Chall, Soumya Sundar Mati, Indranee Das, Amrita Kundu, Goutam De, Krishnananda Chattopadhyay
Fluorescent metal nanoclusters have generated considerable excitement in nanobiotechnology, particularly in the applications of biolabeling, targeted delivery, and biological sensing. The present work is an experimental and computational study that aims to understand the effects of protein environment on the synthesis and electronic properties of gold nanoclusters. MPT63, a drug target of Mycobacterium tuberculosis, was used as the template protein to synthesize, for the first time, gold nanoclusters at a low micromolar concentration of the protein...
October 20, 2017: Langmuir: the ACS Journal of Surfaces and Colloids
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