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gold nanocluster

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https://www.readbyqxmd.com/read/28628726/coinage-metal-superatomic-cores-insights-into-their-intrinsic-stability-and-optical-properties-from-relativistic-dft-calculations
#1
Alvaro Rafael Muñoz-Castro, Franck Gam, Dayan Paez-Hernandez, Ramiro Arratia-Perez, C W Liu, Samia Kahlal, Jean-Yves Saillard
Coinage-metal atomically precise nanoclusters are made of a well-defined metallic core embedded in a ligand-protecting outer shell. Whereas gold derivatives are particularly well documented, examples of silver nanoclusters are somewhat limited and copper species remain particularly scare. Our DFT relativistic calculations on superatomic metallic cores indicate that copper species are almost as stable as gold clusters and more stable than their silver counterparts. Thus, for silver superatomic cores, the role of the stabilizing ligands is more crucial in the stabilization of the overall structure, in comparison to copper and gold...
June 19, 2017: Chemistry: a European Journal
https://www.readbyqxmd.com/read/28604877/understanding-and-improving-aggregated-gold-nanoparticle-dsdna-interactions-by-molecular-spectroscopy-and-deconvolution-methods
#2
Jose M Carnerero, Aila Jimenez-Ruiz, Elia M Grueso, Rafael Prado-Gotor
It is well known that single-stranded DNA (ssDNA) is easily able to adsorb on citrate-capped, non-functionalized gold nanoparticles (AuNPs). However, the affinity of double-stranded DNA (dsDNA) for them is much more limited. The present work demonstrates that long dsDNA suffers from a bending conformational change when anionic nanoparticles are present in solution. A striking decrease in the persistence length of the double helix in the absence of salt is observed through dynamic light scattering (DLS), viscometric, and atomic force microscopy (AFM) methods...
June 21, 2017: Physical Chemistry Chemical Physics: PCCP
https://www.readbyqxmd.com/read/28595000/antimicrobial-gold-nanoclusters
#3
Kaiyuan Zheng, Magdiel I Setyawati, David Tai Leong, Jianping Xie
Bulk gold (Au) is known to be chemically inactive. However, when the size of Au nanoparticles (Au NPs) decreases to close to 1 nm or sub-nanometer dimensions, these ultrasmall Au nanoclusters (Au NCs) begin to possess interesting physical and chemical properties and likewise spawn different applications when working with bulk Au or even Au NPs. In this study, we found that it is possible to confer antimicrobial activity to Au NPs through precise control of their size down to NC dimension (typically less than 2 nm)...
June 13, 2017: ACS Nano
https://www.readbyqxmd.com/read/28582716/combination-of-active-targeting-enzyme-triggered-release-and-fluorescent-dye-into-gold-nanoclusters-for-endomicroscopy-guided-photothermal-photodynamic-therapy-to-pancreatic-ductal-adenocarcinoma
#4
Hui Li, Ping Wang, Yunxiang Deng, Meiying Zeng, Yan Tang, Wei-Hong Zhu, Yingsheng Cheng
Pancreatic ductal adenocarcinoma (PDAC) is one of the most devastating malignancies in patients, and there is an urgent need for an effective treatment method. Herein, we report a novel gold nanocluster-based platform for confocal laser endomicroscopy-guided photothermal therapy (PTT)/photodynamic therapy (PDT) for PDAC, which consists of four components: the PTT-carrier gold nanocluster, an active targeting ligand U11 peptide, a Cathepsin E (CTSE)-sensitive PDT therapy prodrug, and a CTSE-sensitive imaging agent (cyanine dye Cy5...
September 2017: Biomaterials
https://www.readbyqxmd.com/read/28571343/spherical-harmonics-based-descriptor-for-neural-network-potentials-structure-and-dynamics-of-au147-nanocluster
#5
Shweta Jindal, Siva Chiriki, Satya S Bulusu
We propose a highly efficient method for fitting the potential energy surface of a nanocluster using a spherical harmonics based descriptor integrated with an artificial neural network. Our method achieves the accuracy of quantum mechanics and speed of empirical potentials. For large sized gold clusters (Au147), the computational time for accurate calculation of energy and forces is about 1.7 s, which is faster by several orders of magnitude compared to density functional theory (DFT). This method is used to perform the global minimum optimizations and molecular dynamics simulations for Au147, and it is found that its global minimum is not an icosahedron...
May 28, 2017: Journal of Chemical Physics
https://www.readbyqxmd.com/read/28570785/dual-action-cancer-therapy-with-targeted-porous-silicon-nanovectors
#6
Anna Cifuentes-Rius, Angela Ivask, Ester Sporleder, Ishdeep Kaur, Yasmin Assan, Shasha Rao, David Warther, Clive A Prestidge, Jean-Olivier Durand, Nicolas H Voelcker
There is a pressing need to develop more effective therapeutics to fight cancer. An idyllic chemotherapeutic is expected to overcome drug resistance of tumors and minimize harmful side effects to healthy tissues. Antibody-functionalized porous silicon nanoparticles loaded with a combination of chemotherapy drug and gold nanoclusters (AuNCs) are developed. These nanocarriers are observed to selectively deliver both payloads, the chemotherapy drug and AuNCs, to human B cells. The accumulation of AuNCs to target cells and subsequent exposure to an external electromagnetic field in the microwave region render them more susceptible to the codelivered drug...
June 1, 2017: Small
https://www.readbyqxmd.com/read/28560348/molecular-surgery-on-a-23-gold-atom-nanoparticle
#7
Qi Li, Tian-Yi Luo, Michael G Taylor, Shuxin Wang, Xiaofan Zhu, Yongbo Song, Giannis Mpourmpakis, Nathaniel L Rosi, Rongchao Jin
Compared to molecular chemistry, nanochemistry is still far from being capable of tailoring particle structure and functionality at an atomic level. Numerous effective methodologies that can precisely tailor specific groups in organic molecules without altering the major carbon bones have been developed, but for nanoparticles, it is still extremely difficult to realize the atomic-level tailoring of specific sites in a particle without changing the structure of other parts (for example, replacing specific surface motifs and deleting one or two metal atoms)...
May 2017: Science Advances
https://www.readbyqxmd.com/read/28559316/electron-localization-in-rod-shaped-triicosahedral-gold-nanocluster
#8
Meng Zhou, Renxi Jin, Matthew Y Sfeir, Yuxiang Chen, Yongbo Song, Rongchao Jin
Atomically precise gold nanocluster based on linear assembly of repeating icosahedrons (clusters of clusters) is a unique type of linear nanostructure, which exhibits strong near-infrared absorption as their free electrons are confined in a one-dimensional quantum box. Little is known about the carrier dynamics in these nanoclusters, which limit their energy-related applications. Here, we reported the observation of exciton localization in triicosahedral Au37 nanoclusters (0.5 nm in diameter and 1.6 nm in length) by measuring femtosecond and nanosecond carrier dynamics...
May 30, 2017: Proceedings of the National Academy of Sciences of the United States of America
https://www.readbyqxmd.com/read/28551120/gold-nanoclusters-as-fluorescent-sensors-for-selective-and-sensitive-hydrogen-sulfide-detection
#9
Yan Zhang, Min Li, Qinqin Niu, Pengfei Gao, Guomei Zhang, Chuan Dong, Shaomin Shuang
As a highly toxic environmental pollutant and also an important gasotransmitter in diverse physiological processes, the selective and sensitive detection of hydrogen sulfide (H2S) is very significant. In this work, acetylcysteine stabilized gold nanoclusters (ACC@AuNCs)-based fluorescent sensors had been successfully constructed for H2S perception. The sensing principle was that H2S-induced fluorescence quenching of AuNCs which attributed to both the formation of Au2S between Au(I) in the AuNCs and H2S and the increased particle size...
August 15, 2017: Talanta
https://www.readbyqxmd.com/read/28549294/chiral-recognition-of-naproxen-enantiomers-based-on-fluorescence-quenching-of-bovine-serum-albumin-stabilized-gold-nanoclusters
#10
Marzieh Jafari, Javad Tashkhourian, Ghodratollah Absalan
A simple, fast and green method for chiral recognition of S- and R-naproxen has been introduced. The method was based on quenching of the fluorescence intensity of bovine serum albumin-stabilized gold nanoclusters in the presence of naproxen enantiomers. The quenching intensity in the presence of S-naproxen was higher than R-naproxen when phosphate buffer solution at pH7.0 was used. The chiral recognition occurred due to steric effect between bovine serum albumin conformation and naproxen enantiomers. Two linear determination range were established as 7...
May 16, 2017: Spectrochimica Acta. Part A, Molecular and Biomolecular Spectroscopy
https://www.readbyqxmd.com/read/28544757/eight-electron-silver-and-mixed-gold-silver-nanoclusters-stabilized-by-selenium-donor-ligands
#11
Wan-Ting Chang, Po-Yi Lee, Jian-Hong Liao, Kiran Kumarvarma Chakrahari, Samia Kahlal, Yu-Chiao Liu, Ming-Hsi Chiang, Jean-Yves Saillard, C W Liu
The first atomically and structurally precise silver-nanoclusters stabilized by Se-donor ligands, [Ag20 {Se2 P(O(i) Pr)2 }12 ] (3) and [Ag21 {Se2 P(OEt)2 }12 ](+) (4), were isolated by ligand replacement reaction of [Ag20 {S2 P(O(i) Pr)2 }12 ] (1) and [Ag21 {S2 P(O(i) Pr)2 }12 ](+) (2), respectively. Furthermore, doping reactions of 4 with Au(PPh3 )Cl resulted in the formation of [AuAg20 {Se2 P(OEt)2 }12 ](+) (5). Structures of 3, 4, and 5 were determined by single-crystal X-ray diffraction. The anatomy of cluster 3 with an Ag20 core having C3 symmetry is very similar to that of its dithiophosphate analogue 1...
May 22, 2017: Angewandte Chemie
https://www.readbyqxmd.com/read/28531986/biomimicking-synthesis-of-photoluminescent-molecular-lantern-catalyzed-by-in-situ-formation-of-nanogold-catalysts
#12
Yong Yu, Xin Ting Zheng, Boon Wei Yee, Yen Nee Tan
Bioluminescence has been widely recognized as a powerful imaging tool for biological investigations. Synthesis of molecular lanterns that mimic bioluminescence in nature is of great interest. Herein we report a synthesis of molecular lantern by utilizing the catalytic properties of ultrasmall (<2nm) gold nanoclusters (AuNC), which is inspired by the enzymatic light-up of luciferin in the biological system. Small molecules such as hydroquinone and Cys-Gly peptides are used to direct the synthesis of AuNC via a biotemplating approach, while the in-situ formation of AuNC simultaneously catalyze the formation of luciferin-like, brightly fluorescent dye (λem=520nm, QY=0...
August 1, 2017: Materials Science & Engineering. C, Materials for Biological Applications
https://www.readbyqxmd.com/read/28513673/stability-electronic-structure-and-optical-properties-of-protected-gold-doped-silver-ag29-xaux-x-0-5-nanoclusters
#13
Rosalba Juarez-Mosqueda, Sami Malola, Hannu Häkkinen
In this work, we used density functional theory (DFT) and linear response time-dependent DFT (LR-TDDFT) to investigate the stability, electronic structure, and optical properties of Au-doped [Ag29-xAux(BDT)12(TPP)4](3-) nanoclusters (BDT: 1,3-benzenedithiol; TPP triphenylphosphine) with x = 0-5. The aim of this work is to shed light on the most favorable doped structures by comparing our results with previously published experimental data. The calculated relative energies, ranging between 0.8 and 10 meV per atom, indicate that several doped Ag29-xAux nanoclusters are likely to co-exist at room temperature...
May 31, 2017: Physical Chemistry Chemical Physics: PCCP
https://www.readbyqxmd.com/read/28509427/self-supplying-o2-through-the-catalase-like-activity-of-gold-nanoclusters-for-photodynamic-therapy-against-hypoxic-cancer-cells
#14
Ching-Ping Liu, Te-Haw Wu, Chia-Yeh Liu, Kuan-Chung Chen, Yu-Xing Chen, Gin-Shin Chen, Shu-Yi Lin
Photodynamic therapy (PDT) typically involves oxygen (O2 ) consumption and therefore suffers from greatly limited anticancer therapeutic efficacy in tumor hypoxia. Here, it is reported for the first time that amine-terminated, PAMAM dendrimer-encapsulated gold nanoclusters (AuNCs-NH2 ) can produce O2 for PDT via their intrinsic catalase-like activity. The AuNCs-NH2 not only show optimum H2 O2 consumption via the catalase-like activity over the physiological pH range (i.e., pH 4.8-7.4), but also extend such activity to acidic conditions...
May 16, 2017: Small
https://www.readbyqxmd.com/read/28507699/polylysine-grafted-au144-nanoclusters-birth-and-growth-of-a-healthy-surface-plasmon-resonance-like-band
#15
Ivan Guryanov, Federico Polo, Evgeniy V Ubyvovk, Evgenia Korzhikova-Vlakh, Tatiana Tennikova, Armin T Rad, Mu-Ping Nieh, Flavio Maran
Poly(amino acid)-coated gold nanoparticles hold promise in biomedical applications, particularly because they combine the unique physicochemical properties of the gold core, excellent biocompatibility, and easy functionalization of the poly(amino acid)-capping shell. Here we report a novel method for the preparation of robust hybrid core-shell nanosystems consisting of a Au144 cluster and a densely grafted polylysine layer. Linear polylysine chains were grown by direct N-carboxyanhydride (NCA) polymerization onto ligands capping the gold nanocluster...
April 1, 2017: Chemical Science
https://www.readbyqxmd.com/read/28504415/highly-luminescent-folate-functionalized-au22-nanoclusters-for-bioimaging
#16
Kyunglim Pyo, Nguyen Hoang Ly, Sook Young Yoon, Yiming Shen, Seon Young Choi, So Yeong Lee, Sang-Woo Joo, Dongil Lee
Gold nanoclusters are emerging as new materials for biomedical applications because of promises offered by their ultrasmall size and excellent biocompatibility. Here, the synthesis and optical and biological characterizations of a highly luminescent folate-functionalized Au22 cluster (Au22 -FA) are reported. The Au22 -FA clusters are synthesized by functionalizing the surface of Au22 (SG)18 clusters, where SG is glutathione, with benzyl chloroformate and folate. The functionalized clusters are highly water-soluble and exhibit remarkably bright luminescence with a quantum yield of 42%, significantly higher than any other water-soluble gold clusters protected with thiolate ligands...
May 15, 2017: Advanced Healthcare Materials
https://www.readbyqxmd.com/read/28501207/novel-bimetallic-gold-silver-nanoclusters-with-synergy-enhanced-fluorescence-for-cyanide-sensing-cell-imaging-and-temperature-sensing
#17
Lu Tian, Yangfan Li, Tingting Ren, Yaoli Tong, Binsheng Yang, Yingqi Li
We herein opened up a facile and green strategy for the fabrication of bright orange-fluorescent gold-silver nanoclusters (AuAgNCs@ew, GSNCs) by a one-pot synthesis at a vital molar ratio of Au/Ag precursors in the egg white protein matrix using microwave-assisted method. The prepared GSNCs exhibited enhanced fluorescence with fluorescent quantum yield of 5.4%, which is dependent on gold and silver synergies. Due to the advantageous superiority of low-toxicity, excellent stability and satisfactory fluorescence, the as-prepared GSNCs has been successfully used in cell imaging and temperature sensing...
August 1, 2017: Talanta
https://www.readbyqxmd.com/read/28501164/a-nanocluster-based-fluorescent-sensor-for-sensitive-hemoglobin-detection
#18
Dongqin Yang, Huijie Meng, Yifeng Tu, Jilin Yan
In this report, a fluorescence sensor for sensitive detection of hemoglobin was developed. Gold nanoclusters were first synthesized with bovine serum albumin. It was found that both hydrogen peroxide and hemoglobin could weakly quench the fluorescence from the gold nanoclusters, but when these two were applied onto the nanolcusters simultaneously, a much improved quenching was resulted. This enhancing effect was proved to come from the catalytic generation of hydroxyl radical by hemoglobin. Under an optimized condition, the quenching linearly related to the concentration of hemoglobin in the range of 1-250nM, and a limit of detection as low as 0...
August 1, 2017: Talanta
https://www.readbyqxmd.com/read/28497012/electrocatalytic-oxidation-of-alcohols-tripropylamine-and-dna-with-ligand-free-gold-nanoclusters-on-nitrided-carbon
#19
Huiqin Yao, Ben Liu, Islam M Mosa, Itti Bist, Jie He, James F Rusling
Electrocatalytic properties of ligand-free gold nanoclusters (AuNCs, <2 nm) grown on nitrided carbon supports (denoted as AuNCs@N-C) were evaluated for the oxidation of representative organic molecules including alcohols, an amine, and deoxyguanosine in oligonucleotides. AuNCs@N-C catalysts were incorporated into films of architecture {PDDA/AuNCs@N-C} n by using layer-by-layer assembly with oppositely charged poly(diallyldimethylammonium) (PDDA) on pyrolytic graphite (PG) electrodes. Cyclic voltammetry and electrochemical impedance spectroscopy (EIS) were used to survey the electrocatalytic properties of these AuNCs@N-C films...
December 2016: ChemElectroChem
https://www.readbyqxmd.com/read/28492304/deep-red-fluorescent-gold-nanoclusters-for-nucleoli-staining-real-time-monitoring-of-the-nucleolar-dynamics-in-reverse-transformation-of-malignant-cells
#20
Xiaojuan Wang, Yanan Wang, Hua He, Xiqi Ma, Qi Chen, Shuai Zhang, Baosheng Ge, Shengjie Wang, Werner M Nau, Fang Huang
Nucleoli are important subnuclear structures inside cells. We report novel fluorescent gold nanoclusters (K-AuNCs) that are able to stain the nucleoli selectively and make it possible to explore the nucleolar morphology with fluorescence imaging technique. This novel probe is prepared through an easy synthesis method by employing a tripeptide (Lys-Cys-Lys) as the surface ligand. The properties, including deep-red fluorescence emission (680 nm), large Stocks shift, broad excitation band, low cytotoxicity, and good photostability, endow this probe with potential for bioanalytical applications...
May 17, 2017: ACS Applied Materials & Interfaces
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