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gold nanocluster

Seongyeon Cho, Ho Yun Shin, Moon Il Kim
Although protein-stabilized gold nanoclusters (AuNCs) have gathered recent attention as biocompatible peroxidase mimics, their practical utility has been critically limited by the low catalytic activity. Here, the authors have developed a nanohybrid material to significantly enhance the catalytic activity of AuNCs by combining them with other inorganic enzyme mimetics, Fe3O4 magnetic nanoparticles (MNPs), through electrostatic attraction. Owing to the synergistic effect by incorporating AuNCs and MNPs, the constructed nanohybrids yielded highly enhanced catalytic activity and enabled rapid catalytic oxidation of 3,3',5,5'-tetramethylbenzidine substrate to produce a blue-colored solution in proportional to the amount of H2O2...
January 17, 2017: Biointerphases
Kuncheng Yang, Shanshan Wang, Yingyi Wang, Hong Miao, Xiaoming Yang
Herein, carbon dots (CD@Papain) from papain have been originally synthesized in aqueous solution along with a quantum yield of 6.2%, and showed cyan fluorescence at 435nm. Meanwhile, papain-templated Au nanoclusters (AuNCs@Papain) were prepared with the same precursor. On the basis of the two types of nanomaterials, CD@Papain and AuNCs@Papain have been designed to assemble as one nanosensor (termed as CD-AuNCs@Papain) through a typical cross-linking reaction. Significantly, it not only emitted the dual-emission fluorescent signals with the same excitation, but also can assay multiple targets through exhibiting cyan, yellow, and red emission respectively...
January 7, 2017: Biosensors & Bioelectronics
Mahdi Hesari, Zhifeng Ding
In most cases of semiconductor quantum dot nanocrystals, the inherent optical and electrochemical properties of these interesting nanomaterials do not translate into expected efficient electrochemiluminescence or electrogenerated chemiluminescence (ECL) because of the surface-state induction effect. Thus, their low ECL efficiencies, while very interesting to explore, limit their applications. As their electrochemistry is not well-defined, insight into their ECL mechanistic details is also limited. Alternatively, gold nanoclusters possess monodispersed sizes with atomic precision, low and well defined HOMO-LUMO energy gaps, and stable optical and electrochemical properties that make them suitable for potential ECL applications...
January 12, 2017: Accounts of Chemical Research
Shuo Zhao, Renxi Jin, Hadi Abroshan, Chenjie Zeng, Hui Zhang, Stephen D House, Eric Gottlieb, Hyung J Kim, Judith C Yang, Rongchao Jin
Electrocatalytic water splitting to produce hydrogen comprises the hydrogen and oxygen evolution half reactions (HER and OER), with the latter as the bottleneck process. Thus, enhancing the OER performance and understanding the mechanism are critically important. Herein, we report a strategy for OER enhancement by utilizing gold nanoclusters to form cluster/CoSe2 composites; the latter exhibit largely enhanced OER activity in alkaline solutions. The Au25/CoSe2 composite affords a current density of 10 mA cm-2 at small overpotential of ~0...
January 9, 2017: Journal of the American Chemical Society
Anushree Dutta, Deepanjalee Dutta, Pallab Sanpui, Arun Chattopadhyay
A luminescent probe synthesised via biomimetic crystallization of zinc phosphate in the presence of protein fragment stabilised gold (Au) nanoclusters is reported. The engineered probe - with Au nanoclusters assembled on the crystal - was protease resistant and offered efficient bioimaging and uptake studies.
January 19, 2017: Chemical Communications: Chem Comm
Saravanan Govindaraju, Seshadri Reddy Ankireddy, Buddolla Viswanath, Jongsung Kim, Kyusik Yun
Since the last two decades, protein conjugated fluorescent gold nanoclusters (NCs) owe much attention in the field of medical and nanobiotechnology due to their excellent photo stability characteristics. In this paper, we reported stable, nontoxic and red fluorescent emission BSA-Au NCs for selective detection of L-dopamine (DA) in cerebrospinal fluid (CSF). The evolution was probed by various instrumental techniques such as UV-vis spectroscopy, High resolution transmission electron microscopy (HTEM), X-ray photoelectron spectroscopy (XPS), X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), photoluminescence spectroscopy (PL)...
January 9, 2017: Scientific Reports
Wenxiu Hou, Fangfang Xia, Gabriel Alfranca, Hao Yan, Xiao Zhi, Yanlei Liu, Chen Peng, Chunlei Zhang, Jesus Martinez de la Fuente, Daxiang Cui
It is essential to develop a simple synthetic strategy to improve the quality of multifunctional contrast agents for cancer diagnosis. Herein, we report a time-saving method for gadolinium (Gd(3+)) ions-mediated self-assembly of gold nanoclusters (GNCs) into monodisperse spherical nanoparticles (GNCNs) under mild conditions. The monodisperse, regular and colloidal stable GNCNs were formed via selectively inducing electrostatic interactions between negatively-charged carboxylic groups of gold nanoclusters and trivalent cations of gadolinium in aqueous solution...
December 27, 2016: Biomaterials
Sejin Son, Namho Kim, Dong Gil You, Hong Yeol Yoon, Ji Young Yhee, Kwangmeyung Kim, Ick Chan Kwon, Sun Hwa Kim
Nucleic acid-directed self-assembly provides an attractive method to fabricate prerequisite nanoscale structures for a wide range of technological applications due to the remarkable programmability of DNA/RNA molecules. In this study, exquisite RNAi-AuNP nanoconstructs with various geometries were developed by utilizing anti-VEGF siRNA molecules as RNAi-based therapeutics in addition to their role as building blocks for programmed self-assembly. In particular, the anti-VEGF siRNA-functionalized AuNP nanoconstructs can take additional advantage of gold-nanoclusters for photothermal cancer therapeutic agent...
2017: Theranostics
Joao Paulo Coelho, Maria Jose Mayoral, Luis Camacho, María T Martín-Romero, Gloria Tardajos, Iván López-Montero, Eduardo Sanz, David Avila Brande, Juan Jose Giner-Casares, Gustavo Fernández, Andrés Guerrero-Martínez
The ability to respond towards mechanical stimuli is a fundamental property of biological organisms both at the macroscopic and cellular level, yet it has been considerably less observed in artificial supramolecular and colloidal homologues. An archetypal example in this regard is cellular mechanosensation, a process by which mechanical forces applied on the cell membrane are converted into biochemical or electrical signals through nanometer-scale changes in molecular conformations. In this article, we report an artificial gold nanoparticle (Au NP)-discrete π-conjugated molecule hybrid system that mimics the mechanical behavior of biological membranes and is able to self-assemble into colloidal gold nanoclusters or membranes in a controlled and reversible fashion by changing the concentration or the mechanical force (pressure) applied...
December 30, 2016: Journal of the American Chemical Society
Hwa Seung Han, Ki Young Choi, Hansang Lee, Minchang Lee, Jae Yoon An, Sol Shin, Seunglee Kwon, Doo Sung Lee, Jae Hyung Park
Optically active nanomaterials have shown great promise as a nanomedicine platform for photothermal or photodynamic cancer therapies. Herein, we report a gold-nanoclustered hyaluronan nanoassembly (GNc-HyNA) for photothermally boosted photodynamic tumor ablation. Unlike other supramolecular gold constructs based on gold nanoparticle building blocks, this system utilizes the nanoassembly of amphiphilic hyaluronan conjugates as a drug carrier for a hydrophobic photodynamic therapy agent verteporfin, a polymeric reducing agent, and an organic nanoscaffold upon which gold can grow...
December 27, 2016: ACS Nano
Xu Yan, Hongxia Li, Tianyu Hu, Xingguang Su
Assays for organophosphorus pesticides (OPs) with high sensitivity as well as on-site screening have been urgently required to protect ecosystem and prevent disease. Herein, a novel fluorimetric sensing platform was constructed for quantitative detection of OPs via tyrosinase (TYR) enzyme-controlled quenching of gold nanoclusters (AuNCs). One-step green synthetic approach was developed for the synthesis of AuNCs by using chicken egg white (CEW) as template and stabilizer. Initially, TYR can catalyze the oxidation of dopamine to dopaminechrome, which can efficiently quench the fluorescence intensity of AuNCs at 630nm based on dynamic quenching process...
November 25, 2016: Biosensors & Bioelectronics
Wei Wang, Ting Bao, Xi Zeng, Huayu Xiong, Wei Wen, Xiuhua Zhang, Shengfu Wang
In this work, a novel and ultrasensitive electrochemical biosensor was constructed for DNA detection based on functionalized gold clusters/graphene nanohybrids (AuNCs/GR nanobybrids) and exonuclease III (Exo III)-aided cascade target recycling. By utilizing the capacity of GR as universal template, different metal nanoclusters including AuNCs/GR nanobybrids and PtNCs/GR nanohybrids were synthesized through convenient ultrasonic method. Exo III-aided cascade recycling was initiated by target DNA, generating the final cleavage product (S2), which acted as a linkage between capture probe and the functionalized metal nanoclusters/GR conjugates in the construction of the biosensor...
December 10, 2016: Biosensors & Bioelectronics
Mengqun Yu, Zheguo Zhu, Hong Wang, Linyao Li, Fei Fu, Yang Song, Erqun Song
In this paper, the cheap, easily obtained small antibiotic molecule of vancomycin was employed as reducer/stabilizer for facile one-pot synthesis of water exhibited a bluish fluorescence emission at 410nm within a short synthesis time about 50min. Based on the strong fluorescence quenching due to electron transfer mechanism by the introduction of ferric ions(Fe(3+)), the Van-AuNCs were interestingly designed for sensitive and selective detecting Fe(3+) with a limit of 1.4μmol L(-1) in the linear range of 2-100μmol L(-1) within 20min...
November 23, 2016: Biosensors & Bioelectronics
A Muthurasu, V Ganesh
Biomolecules assisted preparation of fluorescent gold nanoparticles (FL-Au NPs) has been reported in this work using glucose oxidase enzyme as both reducing and stabilizing agent and demonstrated their application through multimodal sensing strategy for selective detection of cysteine (Cys). Three different methods namely fluorescence turn OFF-ON strategy, naked eye detection and electrochemical methods are used for Cys detection by employing FL-Au NPs as a common probe. In case of fluorescence turn-OFF method a strong interaction between Au NPs and thiol results in quenching of fluorescence due to replacement of glucose oxidase by Cys at neutral pH...
December 22, 2016: Scientific Reports
María Godoy-Gallardo, Cédric Labay, Michelle M T Jansman, Pramod K Ek, Leticia Hosta-Rigau
The creation of artificial organelles is a new paradigm in medical therapy that aims to substitute for missing cellular function by replenishing a specific cellular task. Artificial organelles tackle the challenge of mimicking metabolism, which is the set of chemical reactions that occur within a cell, mainly catalyzed by enzymes. So far, the few reported carriers able to conduct enzymatic reactions intracellularly are based on single-compartment carriers. However, cell organelles outperform by conducting multiple reactions simultaneously within confined sub-compartments...
December 22, 2016: Advanced Healthcare Materials
N Duane Loh, Soumyo Sen, Michel Bosman, Shu Fen Tan, Jun Zhong, Christian A Nijhuis, Petr Král, Paul Matsudaira, Utkur Mirsaidov
The nucleation and growth of solids from solutions impacts many natural processes and is fundamental to applications in materials engineering and medicine. For a crystalline solid, the nucleus is a nanoscale cluster of ordered atoms that forms through mechanisms still poorly understood. In particular, it is unclear whether a nucleus forms spontaneously from solution via a single- or multiple-step process. Here, using in situ electron microscopy, we show how gold and silver nanocrystals nucleate from supersaturated aqueous solutions in three distinct steps: spinodal decomposition into solute-rich and solute-poor liquid phases, nucleation of amorphous nanoclusters within the metal-rich liquid phase, followed by crystallization of these amorphous clusters...
January 2017: Nature Chemistry
Liren Liu, Jinyun Yuan, Longjiu Cheng, Jinlong Yang
Revealing the stability and structural patterns is important for precisely synthesizing or assembling ligand protected nanoclusters, and even their applications as functional nanomaterials. Investigations on structural evolutional patterns and structural stability are very challenging, because structures change with the nanocluster size and the structural stability depends on both the electron structures of cores and ligand type. Herein, we propose a hybrid superatom network (hSAN) model to understand the stability of some gold nanoclusters with different kinds of ligands...
December 20, 2016: Nanoscale
V Dichiarante, I Tirotta, L Catalano, G Terraneo, G Raffaini, M R Chierotti, R Gobetto, F Baldelli Bombelli, P Metrangolo
A novel class of superfluorinated and NIR-luminescent gold nanoclusters were obtained starting from a branched thiol, bearing 27 equivalent (19)F atoms per molecule. These unprecedented clusters combine in a unique nanosystem both NIR photoluminescence and (19)F NMR properties, thus representing a promising multimodal platform for bioimaging applications.
January 3, 2017: Chemical Communications: Chem Comm
Xiaohui Gao, Shuijian He, Chunmei Zhang, Cheng Du, Xi Chen, Wei Xing, Shengli Chen, Andre Clayborne, Wei Chen
Organic ligand-protected metal nanoclusters have attracted extensively attention owing to their atomically precise composition, determined atom-packing structure and the fascinating properties and promising applications. To date, most research has been focused on thiol-stabilized gold and silver nanoclusters and their single crystal structures. Here the single crystal copper nanocluster species (Cu6(SC7H4NO)6) determined by X-ray crystallography and mass spectrometry is presented. The hexanuclear copper core is a distorted octahedron surrounded by six mercaptobenzoxazole ligands as protecting units through a simple bridging bonding motif...
December 2016: Advanced Science (Weinheim, Baden-Wurttemberg, Germany)
Srestha Basu, Amaresh Kumar Sahoo, Anumita Paul, Arun Chattopadhyay
Early and easy detection of diseases, using point-of-care and inexpensive devices, not only provides option for early treatment but also reduces the risk of propagation. Herein we report the fabrication of a robust film based luminescence indicator of bilirubin, which can indicate hyperbilirubinemia through the thumb imprint of the patient. The UV-light induced luminescence intensity of the film, made out of chitosan stabilised gold (Au) nanoclusters, which was effectively quenched in the presence of Cu(2+) ions, recovered in the presence of bilirubin from skin or blood serum...
December 15, 2016: Scientific Reports
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