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https://www.readbyqxmd.com/read/29332792/silver-ions-enhanced-auncs-fluorescence-as-a-turn-off-nanoprobe-for-ultrasensitive-detection-of-iodide
#1
Wenli Hou, Yuan Chen, Qiujun Lu, Meiling Liu, Youyu Zhang, Shouzhuo Yao
Fluorescence nanoprobes are frequently employed to construct sensitive biosensors via turn-on and turn-off strategy. In this paper, a novel strategy for ultrasensitive detection of iodide was firstly constructed based on Ag+ regulated photoluminescence enhancement of gold nanoclusters (AuNCs) as a turn-off nanoplatform. In the presence of Ag+, the fluorescence (FL) intensity of AuNCs can be enhanced obviously. When adding iodide ions (I-) in the Ag+-AuNCs, Ag+ can be pulled down from AuNCs and results in quenching of the fluorescent effectively owing to the combination between Ag+ and I-...
April 1, 2018: Talanta
https://www.readbyqxmd.com/read/29328339/reduced-sintering-of-mass-selected-au-clusters-on-sio2-by-alloying-with-ti-an-aberration-corrected-stem-and-computational-study
#2
Yubiao Niu, Philomena Schlexer, Bela Sebok, Ib Chorkendorff, Gianfranco Pacchioni, Richard E Palmer
Au nanoparticles represent the most remarkable example of a size effect in heterogeneous catalysis. However, a major issue hindering the use of Au nanoparticles in technological applications is their rapid sintering. We explore the potential of stabilizing Au nanoclusters on SiO2 by alloying them with a reactive metal, Ti. Mass-selected Au/Ti clusters (400 000 amu) and Au2057 clusters (405 229 amu) were produced with a magnetron sputtering, gas condensation cluster beam source in conjunction with a lateral time-of-flight mass filter, deposited onto a silica support and characterised by XPS and LEIS...
January 12, 2018: Nanoscale
https://www.readbyqxmd.com/read/29314857/efficient-one-pot-synthesis-and-ph-dependent-tuning-of-photoluminescence-and-stability-of-au18-sc2h4co2h-14-cluster
#3
Ramakrishna Itteboina, U Divya Madhuri, Partha Ghosal, Monica Kannan, Tapan Kumar Sau, Tatsuya Tsukuda, Shweta Bhardwaj
Developing efficient ways to control the nanocluster properties and synthesize atomically-precise metal nanoclusters are the foremost goals in the field of metal nanocluster research. In this article, we demonstrate that the direct synthesis of atomically-precise, hydrophilic metal nanoclusters as well as tuning of their properties can be achieved by an appropriate selection of reactants, binding ligand, and their proportions. Thus a facile, single-step method has been developed for the direct synthesis of Au18(SC2H4CO2H)14 nanocluster in an aqueous medium under ambient conditions...
January 9, 2018: Journal of Physical Chemistry. A
https://www.readbyqxmd.com/read/29313532/a-label-free-versatile-and-low-background-chemiluminescence-aptasensing-strategy-based-on-gold-nanocluster-catalysis-combined-with-the-separation-of-magnetic-beads
#4
Yueyue Yao, Xiuzhong Wang, Wenna Duan, Feng Li
A label-free, versatile and low-background chemiluminescence (CL) sensing strategy based on gold nanocluster catalysis combined with the separation of magnetic beads (MBs) was developed. Kanamycin was selected as the target analyte to exhibit the analytical performance of this platform. Two single-stranded DNA (named DNA1 and DNA2) are ingeniously designed. DNA1, containing an aptamer sequence of the targets, was firstly immobilized on the MBs which were modified with many amino groups by amidation reaction...
January 9, 2018: Analyst
https://www.readbyqxmd.com/read/29310302/a-label-free-turn-on-off-fluorescent-sensor-for-the-sensitive-detection-of-cysteine-via-blocking-the-ag-enhancing-glutathione-capped-gold-nanoclusters
#5
Ye Li, Yuan Deng, Xiaodong Zhou, Jiming Hu
A new label-free fluorescent turn-on-off mode for the sensitive detection of cysteine(Cys) and the identification of Cys over glutathione (GSH) was firstly proposed, mainly on the basis of two different combination ways between Ag+ ions and GSH-capped gold nanoclusters, or to say, two different contribution ways to the fluorescence enhancement, Ag+ ions combining with Au core structure and coordinating with carboxylate groups on the surface of gold nanoclusters, respectively (turn-on mode). The Au core-binding Ag+ ions could merely be captured by Cys for its relatively smaller steric hindrance than that of GSH, resulting in the identification of Cys over GSH...
March 1, 2018: Talanta
https://www.readbyqxmd.com/read/29260162/a-comprehensive-study-of-catalytic-morphological-and-electronic-properties-of-ligand-protected-gold-nanoclusters-using-xps-stm-xafs-and-tpd-techniques
#6
Qiyuan Wu, Jiajie Cen, Yue Zhao, Xiao Tong, Yuanyuan Li, Anatoly I Frenkel, Shen Zhao, Alexander Orlov
Ultra-small gold nanoclusters were synthesized via a ligand exchange method and deposited onto different TiO2 supports to study their properties. STM imaging revealed that the as-synthesized gold nanoclusters had 2-D morphology consisting of monolayers of gold atoms. Subsequent XPS, XAFS, and CO oxidation TPD results indicated that heat treatments of gold clusters at different temperatures significantly altered their electronic and catalytic properties due to ligand deprotection and cluster agglomeration.
December 20, 2017: Physical Chemistry Chemical Physics: PCCP
https://www.readbyqxmd.com/read/29220160/plant-protein-directed-synthesis-of-luminescent-gold-nanoclusters-hybrids-for-tumor-imaging
#7
Zhao Li, Haibao Peng, Jialin Liu, Ye Tian, Wuli Yang, Jinrong Yao, Zhengzhong Shao, Xin Chen
Nowadays, fluorescence detection has emerged as one of the most frequently used non-invasive biosensing method to selectively monitor biological processes within living systems. Among fluorescent nanoparticles, gold nanoclusters (AuNCs) have been intensively studied because of their intrinsic fluorescence and their endowed biocompatible surface. Herein, we selected an abundant, low-cost and sustainable plant protein, the pea protein isolate (PPI) for its excellent biocompatibility, biodegradability, and non-allergenic character, to be employed as both a reducing and stabilizing agent to facilely produce AuNCs exhibiting a strong red fluorescence...
December 8, 2017: ACS Applied Materials & Interfaces
https://www.readbyqxmd.com/read/29213060/structural-characterization-of-site-modified-nanocapsid-with-monodispersed-gold-clusters
#8
Marie C Stark, Mo A Baikoghli, Tanja Lahtinen, Sami Malola, Li Xing, Michelle Nguyen, Marina Nguyen, Aria Sikaroudi, Varpu Marjomäki, Hannu Häkkinen, R Holland Cheng
Hepatitis E Virus-like particles self-assemble in to noninfectious nanocapsids that are resistant to proteolytic/acidic mucosal delivery conditions. Previously, the nanocapsid was engineered to specifically bind and enter breast cancer cells, where successful tumor targeting was demonstrated in animal models. In the present study, the nanocapsid surface was modified with a solvent-exposed cysteine to conjugate monolayer protected gold nanoclusters (AuNC). Unlike commercially available gold nanoparticles, AuNCs monodisperse in water and are composed of a discrete number of gold atoms, forming a crystalline gold core...
December 6, 2017: Scientific Reports
https://www.readbyqxmd.com/read/29201613/genome-editing-for-cancer-therapy-delivery-of-cas9-protein-sgrna-plasmid-via-a-gold-nanocluster-lipid-core-shell-nanocarrier
#9
Peng Wang, Lingmin Zhang, Yangzhouyun Xie, Nuoxin Wang, Rongbing Tang, Wenfu Zheng, Xingyu Jiang
The type II bacterial clustered, regularly interspaced, short palindromic repeats (CRISPR)-Cas9 (CRISPR-associated protein) system (CRISPR-Cas9) is a powerful toolbox for gene-editing, however, the nonviral delivery of CRISPR-Cas9 to cells or tissues remains a key challenge. This paper reports a strategy to deliver Cas9 protein and single guide RNA (sgRNA) plasmid by a nanocarrier with a core of gold nanoclusters (GNs) and a shell of lipids. By modifying the GNs with HIV-1-transactivator of transcription peptide, the cargo (Cas9/sgRNA) can be delivered into cell nuclei...
November 2017: Advanced Science (Weinheim, Baden-Wurttemberg, Germany)
https://www.readbyqxmd.com/read/29200263/phenylboronic-acid-templated-gold-nanoclusters-for-mucin-detection-using-a-smartphone-based-device-and-targeted-cancer-cell-theranostics
#10
Deepanjalee Dutta, Sunil Kumar Sailapu, Arun Chattopadhyay, Siddhartha Sankar Ghosh
A phenylboronic acid templated gold nanocluster probe was developed to detect biomarker mucin by non-invasive fluorescence based method using a point of care smartphone based fluorescence detection device. The gold nanocluster probe is able to detect mucin specifically. The same probe was applied for in vitro targeted bio-imaging of HeLa and Hep G2 cancer cells and it demonstrated specific therapeutic effects towards cancer cells as well as multicellular tumor spheroids imparting theranostic property. The module is found to be more effective towards HeLa cells and pathway of cell death was established using flow cytometry based assays...
December 4, 2017: ACS Applied Materials & Interfaces
https://www.readbyqxmd.com/read/29199424/preparation-of-novel-fluorescent-nanocomposites-based-on-au-nanoclusters-and-their-application-in-targeted-detection-of-cancer-cells
#11
Xiaoyu Wang, Junhan Xia, Chun Wang, Lu Liu, Shuxian Zhu, Wei Feng, Lidong Li
Fluorescent gold nanoclusters (AuNCs) have drawn considerable research interests owing to their unique emission properties. However, the environment surrounding the nanocluster greatly influences its luminous behavior. In this work, a novel nanocomposite based on AuNCs with bright fluorescence and high biocompatibility was prepared. In the nanocomposite, mesoporous silica (mSiO2) nanospheres provided a mesoporous framework, which helped to template the formation of ultra-small AuNCs and also prevented their aggregation in different solutions...
December 4, 2017: ACS Applied Materials & Interfaces
https://www.readbyqxmd.com/read/29198110/a-novel-and-label-free-platform-for-microrna-detection-based-on-the-fluorescence-quenching-of-positively-charged-gold-nanoparticles-to-ag-nanoclusters
#12
Xiangmin Miao, Zhiyuan Cheng, Haiyan Ma, Zongbing Li, Ning Xue, Po Wang
A novel strategy was developed for microRNA-155 (miRNA-155) detection based on the fluorescence quenching of positively charged gold nanoparticles ((+)AuNPs) to Ag nanoclusters (AgNCs). In the designed system, DNA-stabilized Ag nanoclusters (DNA/AgNCs) were introduced as fluorescent probes, and DNA-RNA heteroduplexes were formed upon the addition of target miRNA-155. Meanwhile, the (+)AuNPs could be electrostatically adsorbed on the negatively charged single-stranded DNA (ssDNA) or DNA-RNA heteroduplexes to quench the fluorescence signal...
December 4, 2017: Analytical Chemistry
https://www.readbyqxmd.com/read/29195047/fluorescence-enhancement-of-terminal-amine-assembled-on-gold-nanoclusters-and-its-application-to-ratiometric-lysine-detection
#13
Guoliang Liu, Daqian Feng, Dongliang Hua, Tianhao Liu, Gang Qi, Wei Wang
Ratiometric fluorescent sensors have emerged as an attractive tool for analytical sensing and optical imaging due to its providing a built-in self-calibration for environmental effects. However, cumbersome processes of nanoparticles modified with fluorophores for constructing traditional ratiometric sensors limit their further application. Herein, we reported a facile and label-free strategy for constructing ratiometric sensor based on aggregation-induced-emission (AIE) active amine-terminated small molecule on the surface of gold nanoclusters (AuNCs)...
December 1, 2017: Langmuir: the ACS Journal of Surfaces and Colloids
https://www.readbyqxmd.com/read/29194793/dry-etching-with-nanoparticles-formation-of-high-aspect-ratio-pores-and-channels-using-magnetic-gold-nanoclusters
#14
Naveen Reddy Kadasala, Mojib Saei, Gary J Cheng, Alexander Wei
Methods for generating nanopores in substrates typically involve one or more wet-etching steps. Here a fundamentally different approach to produce nanopores in sheet substrates under dry, ambient conditions, using nanosecond-pulsed laser irradiation and magnetic gold nanoclusters (MGNCs) as the etching agents is described. Thermoplastic films (50-75 µm thickness) are coated with MGNCs then exposed to laser pulses with a coaxial magnetic field gradient, resulting in high-aspect ratio channels with tapered cross sections as characterized by confocal fluorescence tomography...
November 30, 2017: Advanced Materials
https://www.readbyqxmd.com/read/29182284/reconstructing-the-surface-of-gold-nanocluster-by-cadmium-doping
#15
Qi Li, Kelly J Lambright, Michael Gilbert Taylor, Kristin Kirschbaum, Tian-Yi Luo, Jianbo Zhao, Giannis Mpourmpakis, Soumitra Mokashi-Punekar, Nathaniel L Rosi, Rongchao Jin
Atomically precise metal nanoclusters with tailored surface structures are important for both fundamental studies and practical applications. The development of new methods for tailoring the surface structure in a controllable manner has long been sought. In this work, we report surface reconstruction induced by cadmium (Cd) doping into the [Au23(SR)16]- (R: cyclohexyl) nanocluster, in which two neighboring surface Au atomic sites "coalesce" into one Cd atomic site and accordingly a new bimetal nanocluster, [Au19Cd2(SR)16]-, is produced...
November 28, 2017: Journal of the American Chemical Society
https://www.readbyqxmd.com/read/29166559/dynamic-nature-of-thiolate-monolayer-in-au25-sr-18-nanoclusters
#16
Giovanni Salassa, Annelies Sels, Fabrizio Mancin, Thomas Burgi
Thiolate monolayer, protecting gold nanocluster, is the principal responsible of their chemical behavior and their interaction with the environment. Understanding the parameters that influence the sta-bility and reactivity of the monolayer will enable its precise and controlled functionalization. Here we present a protocol for the investigation of the monolayer reactivity in Au25(SR)18 based on MALDI mass spectrometry and NMR spectroscopy. Thiol ex-change reaction between cluster and thiol molecules has been inves-tigated showing how this reaction is affected by the thiol affinity for Au25...
November 22, 2017: ACS Nano
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
#17
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
#18
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
#19
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
#20
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
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