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gold nanocluster

Jing Lan, Hong Yan Zou, Qiang Wang, Ping Zeng, Yuan Fang Li, Cheng Zhi Huang
An ultra-sensitive and selective turn off-on fluorescence detection of heparin based on the energy transfer in the BSA-stabilized gold nanoclusters/amino-functionalized graphene oxide (BSA-AuNCs/NH2-GO) hybrids was successfully realized. The BSA-AuNCs containing amounts of carboxyl groups could be absorbed on the surface of NH2-GO through the electrostatic interaction, which resulted in the fluorescence quenching of BSA-AuNCs with high efficiency. However, heparin, possessing high density of negative charge, could compete with BSA-AuNCs to bind NH2-GO and block the energy transfer from BSA-AuNCs to NH2-GO...
December 1, 2016: Talanta
Taiping Qing, Xiaoxiao He, Dinggeng He, Zhihe Qing, Kemin Wang, Yanli Lei, Ting Liu, Peng Tang, Yue Li
In this work, we developed a simple, rapid and mild strategy for synthesis of DNA-templated fluorescent gold nanoclusters (AuNCs) through association of gold ions to DNA templates and reduction with 4-(2-hydroxyethyl)-1-piperazineethanesulfonic acid (HEPES). After systematical investigation on the formation of fluorescent AuNCs by using different DNA templates, C5 DNA was found as the best template for the formation of fluorescent AuNCs in this system. This process could be completed within 5min after the reaction beginning under ambient conditions...
December 1, 2016: Talanta
Zhi Wang, Ravithree Senanayake, Christine M Aikens, Wen-Miao Chen, Chen-Ho Tung, Di Sun
Here we report the single-crystal structure, experimental and theoretical characterization of a 41-metal atom Au-Ag alloy nanocluster [Au3Ag38(SCH2Ph)24X5](2-) (1, X = Cl or Br). The nanocluster 1 is co-protected by thiolate and halogen atoms and features an all-metallic face-fused biicosahedral Au2@AuAg20 rod-like kernel enwrapped by the outermost Ag18(SCH2Ph)24X3 shell. Two sites on the surface of the biicosahedral kernel are partially occupied by Au and Ag atoms. The outer Ag18(SCH2Ph)24X3 shell is composed of two Ag6S6 cycles at the two poles and one Ag6S2X3 arc at the equator with both 2- and 3-coordinated Ag atoms, which has not been observed in gold or silver nanoclusters ever before...
October 17, 2016: Nanoscale
Fu Kit Sheong, Jing-Xuan Zhang, Zhenyang Lin
Recently, many examples of gold nanoclusters have been synthesized due to their exceptional spectroscopic properties and potential applications in nanotechnology. In this work we put forward an approach based on the icosahedral [Au13](5+) unit and summarize three possible extensions of the unit: wrapping, bonding, and vertex sharing. We show that the electronic structure of such clusters can be treated in a more localized manner and show how the approach could be applied to understand the structure and bonding of a large variety of gold nanoclusters...
October 13, 2016: Inorganic Chemistry
Tanja Lahtinen, Eero Hulkko, Karolina Sokołowska, Tiia-Riikka Tero, Ville Saarnio, Johan Lindgren, Mika Pettersson, Hannu Häkkinen, Lauri Lehtovaara
We present the synthesis, separation, and characterization of covalently-bound multimers of para-mercaptobenzoic acid (p-MBA) protected gold nanoclusters. The multimers were synthesized by performing a ligand-exchange reaction of a pre-characterized Au102(p-MBA)44 nanocluster with biphenyl-4,4'-dithiol (BPDT). The reaction products were separated using gel electrophoresis yielding several distinct bands. The bands were analyzed by transmission electron microscopy (TEM) revealing monomer, dimer, and trimer fractions of the nanocluster...
September 21, 2016: Nanoscale
Megalamane S Bootharaju, Lutfan Sinatra, Osman M Bakr
Atomically precise metal nanoclusters (NCs) containing more than one type of metal atom (i.e., doped or alloyed), due to synergistic effects, open new avenues for engineering the catalytic and optical properties of NCs in a manner that homometal NCs cannot. Unfortunately, it is still a major challenge to controllably introduce multimetallic dopants in NCs, understanding the dopants' positions, mechanism, and synergistic effects. To overcome these challenges, we designed a metal-exchange approach involving NCs as molecular templates and metal ions as the source of the incoming dopant...
October 6, 2016: Nanoscale
Lingwen Liao, Jishi Chen, Chengming Wang, Shengli Zhuang, Nan Yan, Chuanhao Yao, Nan Xia, Lingling Li, Xiaoli Bao, Zhikun Wu
Herein, we report the intriguing structure, optical absorption and electrochemical properties of the transition-sized Au92(TBBT)44 (Au92 for short, TBBT = 4-tert-butylbenzenethiolate) nanoparticle. An interesting observation is the 4H phase array of Au92 nanoparticles in the unit cells of single crystals.
October 4, 2016: Chemical Communications: Chem Comm
Jiachen Zang, Changan Li, Kai Zhou, Haisheng Dong, Bin Chen, Fudi Wang, Guanghua Zhao
Owing to diverse functionalities and metal binding abilities, proteins have been proven to be promising ligands in the synthesis of gold nanoclusters (Au NCs). In this work, we explored β-lactoglobulin (β-Lg), a protein byproduct generated during cheese processing, as a biotemplate for fabrication of Au NCs by a facile and green method for the first time. The as-prepared Au NCs are water soluble and highly fluorescent and exhibit high sensitivity and selectivity for Hg(2+) detection in aqueous solution. Interestingly, we found that the fluorescence of these Au NCs is stable either in a variety of complex matrixes or over a broad pH range (5...
October 18, 2016: Analytical Chemistry
Chunqiu Zhao, Tianyu Du, Fawad Ur Rehman, Lanmei Lai, Xiaoli Liu, Xuerui Jiang, Xiaoqi Li, Yun Chen, Hang Zhang, Yi Sun, Shouhua Luo, Hui Jiang, Matthias Selke, Xuemei Wang
Cancer treatment has a far greater chance of success if the neoplasm is diagnosed before the onset of metastasis to vital organs. Hence, cancer early diagnosis is extremely important and remains a major challenge in modern therapeutics. In this contribution, facile and new method for rapid multimodal tumor bioimaging is reported by using biosynthesized iron complexes and gold nanoclusters via simple introduction of AuCl4 (-) and Fe(2+) ions. The observations demonstrate that the biosynthesized Au nanoclusters may act as fluorescent and computed tomography probes for cancer bioimaging while the iron complexes behave as effective contrast agent for magnetic resonance imaging...
September 27, 2016: Small
Jiadong Fan, Zhibin Sun, Yaling Wang, Jaehyun Park, Sunam Kim, Marcus Gallagher-Jones, Yoonhee Kim, Changyong Song, Shengkun Yao, Jian Zhang, Jianhua Zhang, Xiulan Duan, Kensuke Tono, Makina Yabashi, Tetsuya Ishikawa, Chunhai Fan, Yuliang Zhao, Zhifang Chai, Xueyun Gao, Thomas Earnest, Huaidong Jiang
High-resolution imaging offers one of the most promising approaches for exploring and understanding the structure and function of biomaterials and biological systems. X-ray free-electron lasers (XFELs) combined with coherent diffraction imaging can theoretically provide high-resolution spatial information regarding biological materials using a single XFEL pulse. Currently, the application of this method suffers from the low scattering cross-section of biomaterials and X-ray damage to the sample. However, XFELs can provide pulses of such short duration that the data can be collected using the "diffract and destroy" approach before the effects of radiation damage on the data become significant...
2016: Scientific Reports
Yue Ma, Hualin Fu, Chunlei Zhang, Shangli Cheng, Jie Gao, Zhen Wang, Weilin Jin, João Conde, Daxiang Cui
Epigenetic modifications sit 'on top of' the genome and influence DNA transcription, which can force a significant impact on cellular behavior and phenotype and, consequently human development and disease. Conventional methods for evaluating epigenetic modifications have inherent limitations and, hence, new methods based on nanoscale devices are needed. Here, we found that antioxidant (glutathione) chiral gold nanoclusters induce a decrease of 5-hydroxymethylcytosine (5hmC), which is an important epigenetic marker that associates with gene transcription regulation...
2016: Scientific Reports
Taerin Chung, Tugba Koker, Fabien Pinaud
The assembly of plasmonic metal nanoparticles into hot spot surface-enhanced Raman scattering (SERS) nanocluster probes is a powerful, yet challenging approach for ultrasensitive biosensing. Scaffolding strategies based on self-complementary peptides and proteins are of increasing interest for these assemblies, but the electronic and the photonic properties of such hybrid nanoclusters remain difficult to predict and optimize. Here, split-green fluorescence protein (sGFP) fragments are used as molecular glue and the GFP chromophore is used as a Raman reporter to assemble a variety of gold nanoparticle (AuNP) clusters and explore their plasmonic properties by numerical modeling...
September 8, 2016: Small
Chong Liu, Chenjie Zeng, Tian-Yi Luo, Andrea D Merg, Rongchao Jin, Nathaniel L Rosi
Crystalline 3-D materials bearing interlinked domains of differential porosity and functionality offer the potential for organizing and shuttling molecular and nanoscale matter to specific locations within 3-D space. Here, we present methods for creating prototype MOF materials that have such structural features. Specifically, the process of pore expansion via ligand exchange was studied for an isoreticular series of mesoporous MOFs based on bMOF-100. It was found that pore expansion occurs incrementally in small steps and that it proceeds gradually in an "outside→in" fashion within individual crystals...
September 21, 2016: Journal of the American Chemical Society
Rongchao Jin, Chenjie Zeng, Meng Zhou, Yuxiang Chen
Colloidal nanoparticles are being intensely pursued in current nanoscience research. Nanochemists are often frustrated by the well-known fact that no two nanoparticles are the same, which precludes the deep understanding of many fundamental properties of colloidal nanoparticles in which the total structures (core plus surface) must be known. Therefore, controlling nanoparticles with atomic precision and solving their total structures have long been major dreams for nanochemists. Recently, these goals are partially fulfilled in the case of gold nanoparticles, at least in the ultrasmall size regime (1-3 nm in diameter, often called nanoclusters)...
September 28, 2016: Chemical Reviews
Xinyi Wang, Na Wang, Lan Yuan, Na Li, Junxia Wang, Xiaoda Yang
Tight junctions play a key role in restricting or regulating passage of liquids, ions and large solutes through various biological barriers by the paracellular route. Changes in paracellular permeation indicate alteration of the tight junction. However, it is very difficult to obtain the structural change information by measuring paracellular flux based on transepithelial electrical resistance or using fluorescein-labeled dextrans. Here we show that the BSA and GSH stabilized gold nanoclusters exhibit marginal cytotoxicity and pass through the MDCK monolayer exclusively through the paracellular pathway...
2016: Scientific Reports
Jingguo Li, Ricca Rahman Nasaruddin, Yan Feng, Jun Yang, Ning Yan, Jianping Xie
In this work, the effects of thiolate ligands (-SR, e.g., chain length and functional moiety) on the accessibility and catalytic activity of thiolate-protected gold nanoclusters (e.g., Au25 (SR)18 ) for 4-nitrophenol hydrogenation is reported. The data suggest that Au25 (SR)18 bearing a shorter alkyl chain shows a better accessibility to the substrates (shown by shorter induction time, t0 ) and a higher catalytic activity (shown by higher apparent reaction rate constant, kapp ). The functional moiety of the ligands is another determinant factor, which clearly suggests that ligand engineering of Au25 (SR)18 would be an efficient platform for fine-tuning its catalytic properties...
October 10, 2016: Chemistry: a European Journal
Changan Li, Hai Chen, Bin Chen, Guanghua Zhao
Applications of nanotechnology in food have rapidly increased in the past decades. Ultra-small gold nanoclusters (Au NCs), composed of several to roughly a hundred atoms, represent a kind of novel nanomaterials. The Au NCs directed by food proteins have drawn considerable research attention due to their environmentally friendly preparation, strong fluorescence, excellent photo-stability and favorable biocompatibility. These interesting protein-Au hybrids have opened up a new area at the nano-bio-food interface, not only did they provide the missing link between single metal atoms and plasmonic metal nanoparticles, but also developed the hybrid system between biomacromolecule and inorganic ions...
August 24, 2016: Critical Reviews in Food Science and Nutrition
Qi Lei, Jing-Jing Hu, Lei Rong, Han Cheng, Yun-Xia Sun, Xian-Zheng Zhang
Endo/lysosomal escape and subsequent nuclear translocation are recognized as the two major challenges for efficient gene transfection. Herein, nuclear localization signal (NLS) peptide sequences and oligomeric lysine sequences were crosslinked via disulfide bonds to obtain glutathione (GSH) reducible polypeptide (pNLS). The pNLS could condense DNA into compact positive-charged complexes with redox sensitivity, and then gold nanoclusters (AuNC) were further decorated to the surface via electrostatic interactions obtaining versatile pNLS/DNA/AuNC complexes...
2016: Molecules: a Journal of Synthetic Chemistry and Natural Product Chemistry
Jun-Ying Wang, Jie Chen, Jiang Yang, Hao Wang, Xiu Shen, Yuan-Ming Sun, Meili Guo, Xiao-Dong Zhang
Gold nanoclusters (Au NCs) have exhibited great advantages in medical diagnostics and therapies due to their efficient renal clearance and high tumor uptake. The in vivo effects of the surface chemistry of Au NCs are important for the development of both nanobiological interfaces and potential clinical contrast reagents, but these properties are yet to be fully investigated. In this study, we prepared glutathione-protected Au NCs of a similar hydrodynamic size but with three different surface charges: positive, negative, and neutral...
2016: International Journal of Nanomedicine
Shuang Chen, Lin Xiong, Shuxin Wang, Zhongyun Ma, Shan Jin, Hongting Sheng, Yong Pei, Manzhou Zhu
The larger size gold nanoparticles typically adopt a face-centered cubic (fcc) atomic packing, while in the ultrasmall nanoclusters the packing styles of Au atoms are diverse, including fcc, hexagonal close packing (hcp), and body-centered cubic (bcc), depending on the ligand protection. The possible conversion between these packing structures is largely unknown. Herein, we report the growth of a new Au21(S-Adm)15 nanocluster (S-Adm = adamantanethiolate) from Au18(SR)14 (SR = cyclohexylthiol), with the total structure determined by X-ray crystallography...
August 31, 2016: Journal of the American Chemical Society
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