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https://www.readbyqxmd.com/read/28531986/biomimicking-synthesis-of-photoluminescent-molecular-lantern-catalyzed-by-in-situ-formation-of-nanogold-catalysts
#1
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
#2
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 17, 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
#3
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
#4
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
#5
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
#6
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
#7
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
#8
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
#9
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 11, 2017: ACS Applied Materials & Interfaces
https://www.readbyqxmd.com/read/28489408/thermodynamics-and-mechanisms-of-the-interactions-between-ultra-small-fluorescent-gold-nanoclusters-and-human-serum-albumin-%C3%AE-globulins-and-transferrin-a-spectroscopic-approach
#10
Miao-Miao Yin, Ping Dong, Wen-Qi Chen, Shi-Ping Xu, Liyun Yang, Feng-Lei Jiang, Yi Liu
Noble metal nanoclusters (NCs) show great promise as nanoprobes for bioanalysis and cellular imaging in biological applications due to ultra-small size, good photophysical properties and excellent biocompatibility. In order to achieve a comprehensive understanding of possible biological implications, a series of spectroscopic measurements were conducted under different temperatures to investigate the interactions of Au NCs (~1.7 nm) with three model plasmatic proteins (human serum albumin (HSA), γ-globulins and transferrin)...
May 10, 2017: Langmuir: the ACS Journal of Surfaces and Colloids
https://www.readbyqxmd.com/read/28467025/zinc-coordinated-hierarchical-organization-of-ligand-stabilized-gold-nanoclusters-for-chiral-recognition-supplemented-with-separation
#11
Arun Chattopadhyay, Srestha Basu, Anumita Paul
Three dimensional organization of D or L tryptophan and mercaptopropionic acid stabilized gold nanoclusters has been achieved by complexation reaction involving the ligands stabilizing gold nanoclusters and zinc ions. Powder X ray diffraction and transmission electron microscopy analyses substantiated the crystalline nature of the assembly of atomic nanoclusters. The hierarchical arrangement of the nanoclusters exhibited superior optical properties (namely, enhanced photoluminescence and excited state lifetime) as compared to the non-assembled nanoclusters...
May 3, 2017: Chemistry: a European Journal
https://www.readbyqxmd.com/read/28463506/locating-reactive-groups-on-nanomaterials-with-gold-nanoclusters-toward-a-surface-reactive-site-map
#12
Steffi S Thomas, Matthew Coleman, Emma Carroll, Ester Polo, Fabian Meder, Kenneth A Dawson
Nanoparticles (NPs) are often functionalized with reactive groups such as amines and thiols for the subsequent conjugation of further molecules, e.g., stabilizing polymers, drugs, and proteins for targeting cells or specific diseases. In addition to the quantitative estimation of the reactive conjugation sites, their molecular positioning and nanoscale arrangement on single nanoparticles become more and more important for the tailored engineering and design of functional nanomaterials. Here, we use maleimide or sulfo-succinimidyl ester-modified 1...
May 8, 2017: Langmuir: the ACS Journal of Surfaces and Colloids
https://www.readbyqxmd.com/read/28460331/a-novel-fluorometric-and-colorimetric-sensor-for-iodide-determination-using-dna-templated-gold-silver-nanoclusters
#13
Zihao Li, Ruiyi Liu, Guofeng Xing, Tong Wang, Siyu Liu
Determination of iodide ions has attracted considerable interest due to the importance and urgency. In the current work, we have developed a novel fluorescent and colorimetric platform for simple and selective detection of iodide ions based on the DNA-templated gold/silver nanoclusters (DNA-Au/Ag NCs). The detection system is based on the unique interaction between iodide ions and DNA-Au/Ag NCs, which shows an obvious fluorescence quenching with the addition of iodide ions and a good linear range from 0 to 10μmol/L for iodide ions...
January 4, 2017: Biosensors & Bioelectronics
https://www.readbyqxmd.com/read/28458743/eco-friendly-green-synthesis-of-magnetically-active-gold-nanoclusters
#14
Naveen Reddy Kadasala, Lu Lin, Christopher Gilpin, Alexander Wei
Au-FexOy composite nanoparticles (NPs) are of great technological interest due to their combined optical and magnetic properties. However, typical syntheses are neither simple nor ecologically friendly, creating a challenging situation for process scale-up. Here we describe conditions for preparing Au-FexOy NPs in aqueous solutions and at ambient temperatures, without resorting to solvents or amphiphilic surfactants with poor sustainability profiles. These magnetic gold nanoclusters (MGNCs) are prepared in practical yields with average sizes slightly below 100 nm, and surface plasmon resonances that extend to near-infrared wavelengths, and sufficient magnetic moment (up to 6 emu g(-1)) to permit collection within minutes by handheld magnets...
2017: Science and Technology of Advanced Materials
https://www.readbyqxmd.com/read/28444989/water-soluble-naked-gold-nanoclusters-are-not-luminescent
#15
Julia Perez-Prieto, Pablo Londoño-Larrea, Julie P Vanegas, Daniel Cuaran, Elena Zaballos-García
We report here the synthesis of water-dispersible naked gold nanoclusters (AuNCnaked) by a simple reduction of HAuCl4 with NaOH at room temperature and show that they are non-luminescent. They were then easily passivated with different thiols and adenosine monophosphate to lead to luminescent NCs. This is an important finding as the photoluminescence of the passivated NCs can now be clearly attributed to the ligand-AuNC surface interaction. These results are also highly relevant from the point of view of the preparation of luminescent NCs from the same NC batch...
April 26, 2017: Chemistry: a European Journal
https://www.readbyqxmd.com/read/28443925/the-effect-of-ligand-ligand-interactions-on-the-formation-of-photoluminescent-gold-nanoclusters-embedded-in-au-i-thiolate-supramolecules
#16
Hsiang-Yu Chang, Yu-Ting Tseng, Zhiqin Yuan, Hung-Lung Chou, Ching-Hsiang Chen, Bing-Joe Hwang, Meng-Che Tsai, Huan-Tsung Chang, Chih-Ching Huang
In this study, we prepared photoluminescent l-cysteine (Cys)-capped gold nanoclusters (Cys-Au NCs) via NaBH4-mediated reduction of aggregated coordination polymers (supramolecules) of -[Cys-Au(i)]n-. The -[Cys-Au(i)]n- supramolecules with interesting chiral properties were formed through simple reactions of chloroauric acid (HAuCl4) with Cys at certain pH values (pH 3-7). The -[Cys-Au(i)]n- polymers could self-assemble into -[Cys-Au(i)]n- supramolecules with irregular morphologies and diameters larger than 500 nm through stacked hydrogen bonding and zwitterionic interactions between Cys ligands and through Au(i)Au(i) aurophilic interactions in solutions with pH values ≤7...
May 17, 2017: Physical Chemistry Chemical Physics: PCCP
https://www.readbyqxmd.com/read/28440296/gold-nanoclusters-assisted-delivery-of-ngf-sirna-for-effective-treatment-of-pancreatic-cancer
#17
Yifeng Lei, Lixue Tang, Yangzhouyun Xie, Yunlei Xianyu, Lingmin Zhang, Peng Wang, Yoh Hamada, Kai Jiang, Wenfu Zheng, Xingyu Jiang
Pancreatic cancer is one of the deadliest human cancers, whose progression is highly dependent on the nervous microenvironment. The suppression of gene expression of nerve growth factor (NGF) may have great potential in pancreatic cancer treatment. Here we show that gold nanocluster-assisted delivery of siRNA of NGF (GNC-siRNA) allows efficient NGF gene silencing and pancreatic cancer treatment. The GNC-siRNA complex increases the stability of siRNA in serum, prolongs the circulation lifetime of siRNA in blood and enhances the cellular uptake and tumour accumulation of siRNA...
April 25, 2017: Nature Communications
https://www.readbyqxmd.com/read/28419942/nucleotide-directed-syntheses-of-gold-nanohybrid-systems-with-structure-dependent-optical-features-selective-fluorescence-sensing-of-fe-3-ions
#18
Ditta Ungor, Edit Csapó, Barbara Kismárton, Ádám Juhász, Imre Dékány
This study demonstrates a one-step synthesis for the preparation of both adenosine monophosphate (AMP)-stabilized colloidal gold nanoparticles (AMP-Au NPs) and fluorescent gold nanoclusters (AMP-Au NCs). The dominant role of AMP:AuCl4(-) molar ratios in the formation of diverse nanosized Au products was proved. The size, the structure and the unique structure-dependent optical properties of the NPs and NCs were determined based on the results of numerous spectroscopic (UV-vis, fluorescence, infrared, x-ray photoelectron), high resolution electron microscopy (HRTEM) and dynamic light scattering (DLS) techniques...
April 9, 2017: Colloids and Surfaces. B, Biointerfaces
https://www.readbyqxmd.com/read/28411590/effects-of-ordered-islands-on-surface-resistivity-ni-on-au-111
#19
Joshua I Cohen, R G Tobin
The change in surface resistivity due to the formation of nickel islands on gold(111) was studied by measuring the resistance of a thin film of Au as a function of Ni coverage, θ. Previous studies showed that the Au(111) herringbone reconstruction provides a template for the periodic growth of ordered islands. Ni islands grow radially until θ ≈ 0.3 ML, after which subsequent Ni atoms contribute primarily to a second layer. Since Ni atoms on Au(111) grow in ordered nanoclusters, a nonlinear dependence of resistance on θ might be anticipated...
April 14, 2017: Journal of Chemical Physics
https://www.readbyqxmd.com/read/28402112/self-assembled-upconversion-nanoparticle-clusters-for-nir-controlled-drug-release-and-synergistic-therapy-after-conjugation-with-gold-nanoparticles
#20
Huijuan Cai, Tingting Shen, Alexander M Kirillov, Yu Zhang, Changfu Shan, Xiang Li, Weisheng Liu, Yu Tang
Fabricated three-dimensional (3D) upconversion nanoclusters (abbreviated as EBSUCNPs) are obtained via an emulsion-based bottom-up self-assembly of NaGdF4:Yb/Er@NaGdF4 nanoparticles (abbreviated as UCNPs), which comprise a NaGdF4:Yb/Er core and a NaGdF4 shell. The EBSUCNPs were then coated with a thin mesoporous amino-functionalized SiO2 shell (resulting in EBSUCNPs@SiO2 precursor) and further conjugated with gold nanoparticles to give the novel EBSUCNPs@SiO2@Au material. Finally, EBSUCNPs@SiO2@Au was applied as a biocompatible and efficient drug carrier for doxorubicin (DOX), thus giving rise to a multifunctional EBSUCNPs@SiO2-DOX@Au nanocomposite...
April 12, 2017: Inorganic Chemistry
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