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https://www.readbyqxmd.com/read/28900638/acid-and-hydrogen-bonding-induced-switching-between-22-%C3%AF-and-18-%C3%AF-electron-conjugations-in-2-aminothiazolo-4-5-c-porphycenes
#1
Oriol Planas, Daniel Fernández-Llaneza, Ingrid Nieves, Rubén Ruiz-Gonzalez, Else Lemp, Antonio L Zanocco, Santi Nonell
2-Aminothiazolo[4,5-c]porphycenes are a novel class of 22-π electron aromatic porphycene derivatives prepared by click reaction of porphycene isothiocyanates with primary and secondary amines with high potential as near-infrared theranostic labels. Herein, the optical and photophysical properties of 2-aminothiazolo[4,5-c]porphycenes have been studied, revealing a strong dependence on hydrogen bond donor solvents and acids. High hydrogen bond donor solvents and acids shift the absorption and fluorescence emission of 2-aminothiazolo[4,5-c]porphycenes to the blue due to a contraction of their aromatic system from 22-π to 18-π electrons...
September 13, 2017: Physical Chemistry Chemical Physics: PCCP
https://www.readbyqxmd.com/read/28892099/glomerular-barrier-behaves-as-an-atomically-precise-bandpass-filter-in-a-sub-nanometre-regime
#2
Bujie Du, Xingya Jiang, Anindita Das, Qinhan Zhou, Mengxiao Yu, Rongchao Jin, Jie Zheng
The glomerular filtration barrier is known as a 'size cutoff' slit, which retains nanoparticles or proteins larger than 6-8 nm in the body and rapidly excretes smaller ones through the kidneys. However, in the sub-nanometre size regime, we have found that this barrier behaves as an atomically precise 'bandpass' filter to significantly slow down renal clearance of few-atom gold nanoclusters (AuNCs) with the same surface ligands but different sizes (Au18, Au15 and Au10-11). Compared to Au25 (∼1.0 nm), just few-atom decreases in size result in four- to ninefold reductions in renal clearance efficiency in the early elimination stage, because the smaller AuNCs are more readily trapped by the glomerular glycocalyx than larger ones...
September 11, 2017: Nature Nanotechnology
https://www.readbyqxmd.com/read/28875202/direct-self-focusing-synthesis-of-monodisperse-au8-pph3-7-2-nanoclusters
#3
Ting Huang, Li Huang, Yong Jiang, Fengchun Hu, Zhihu Sun, Guoqiang Pan, Shiqiang Wei
Direct and scalable synthesis of monodisperse gold nanoclusters is highly desired but remains a great challenge due to the complexity of chemical reactions. In this regard, a suitable precursor is important as it can simplify the synthesis processes and offer controllability in tuning the product. In this study, we found that Au(PPh3)2Cl could be used as an effective precursor for the direct synthesis of atomically monodisperse [Au8(PPh3)7](2+) nanoclusters without the need of tedious post-synthetic purification steps...
September 6, 2017: Dalton Transactions: An International Journal of Inorganic Chemistry
https://www.readbyqxmd.com/read/28872849/thiol-induced-synthesis-of-phosphine-protected-gold-nanoclusters-with-atomic-precision-and-controlling-the-structure-by-ligand-metal-engineering
#4
Shan Jin, Wenjun Du, Shuxin Wang, Xi Kang, Man Chen, Daqiao Hu, Shuang Chen, Xuejuan Zou, Guodong Sun, Manzhou Zhu
Efficient synthesis of atomically precise phosphine-capped gold nanocluster (with >10 metal atoms) is important to deeply understand the relationship between structure and properties. Herein, we successfully utilize the thiol-induced synthesis method and obtain three atomically precise phosphine-protected gold nanoclusters. Single-crystal X-ray structural analysis reveals that the nanoclusters are formulated as [Au13(Dppm)6](BPh4)3, [Au18(Dppm)6Br4](BPh4)2, and [Au20(Dppm)6(CN)6] (where Dppm stands for bis(diphenylphosphino)methane), which are further confirmed by electrospray ionization mass spectrometry, thermogravimetric analysis, and X-ray photoelectron spectroscopy...
September 5, 2017: Inorganic Chemistry
https://www.readbyqxmd.com/read/28863240/mesoscopic-functionalization-of-silk-fibroin-with-gold-nanoclusters-mediated-by-keratin-and-bioinspired-silk-synapse
#5
Yao Xing, Chenyang Shi, Jianhui Zhao, Wu Qiu, Naibo Lin, Jingjuan Wang, Xiao Bing Yan, Wei Dong Yu, Xiang Yang Liu
Silk fibroin (SF) offers great opportunities in manufacturing biocompatible/partially biodegradable devices with environmental benignity and biomedical applications. To obtain active SF devices of next generation, this work is to demonstrate a new functionalization strategy of the mesoscopic functionalization for soft materials. Unlike the atomic functionalization of solid materials, the meso-functionalization is to incorporate meso-dopants, i.e., functional molecules or nanomaterials, quantum dots, into the mesoscopic networks of soft materials...
September 1, 2017: Small
https://www.readbyqxmd.com/read/28852145/the-impact-of-the-polymer-chain-length-on-the-catalytic-activity-of-poly-n-vinyl-2-pyrrolidone-supported-gold-nanoclusters
#6
Setsiri Haesuwannakij, Tetsunari Kimura, Yuji Furutani, Kazu Okumura, Ken Kokubo, Takao Sakata, Hidehiro Yasuda, Yumi Yakiyama, Hidehiro Sakurai
Poly(N-vinyl-2-pyrrolidone) (PVP) of varying molecular weight (M w  = 40-360 kDa) were employed to stabilize gold nanoclusters of varying size. The resulting Au:PVP clusters were subsequently used as catalysts for a kinetic study on the sized-dependent aerobic oxidation of 1-indanol, which was monitored by time-resolved in situ infrared spectroscopy. The obtained results suggest that the catalytic behaviour is intimately correlated to the size of the clusters, which in turn depends on the molecular weight of the PVPs...
August 29, 2017: Scientific Reports
https://www.readbyqxmd.com/read/28834765/rgd-peptide-modified-fluorescent-gold-nanoclusters-as-highly-efficient-tumor-targeted-radiotherapy-sensitizers
#7
Guohai Liang, Xudong Jin, Shuxu Zhang, Da Xing
Radiotherapy is a leading treatment approach of cancer therapy. While it is effective in killing tumor cells, it can also cause serious damage to surrounding normal tissue. Targeted radiotherapy with gold nanoparticle-based radiosensitizers is actively being investigated, and considered as a promising means to enhance the efficacy of radiotherapy against tumors under a relatively low and safe radiation dose. In this work, we report a green and one-step strategy to synthesize fluorescent gold nanoclusters by using a commercialized cyclic arginine-glycine-aspartic acid (c(RGDyC)) peptide as the template...
August 16, 2017: Biomaterials
https://www.readbyqxmd.com/read/28822859/a-facile-method-to-prepare-green-nano-phosphors-with-a-large-stokes-shift-and-solid-state-enhanced-photophysical-properties-based-on-surface-modified-gold-nanoclusters
#8
C H Cheng, H Y Huang, M J Talite, W C Chou, J M Yeh, C T Yuan
Colloidal nano-materials, such as quantum dots (QDs) have been applied to light-conversion nano-phosphors due to their unique tunable emission. However, most of the QDs involve toxic elements and are synthesized in a hazardous solvent. In addition, conventional QD nano-phosphors with a small Stokes shift suffered from reabsorption losses and aggregation-induced quenching in the solid state. Here, we demonstrate a facile, matrix-free method to prepare eco-friendly nano-phosphors with a large Stokes shift based on aqueous thiolate-stabilized gold nanoclusters (GSH-AuNCs) with simple surface modifications...
August 8, 2017: Journal of Colloid and Interface Science
https://www.readbyqxmd.com/read/28810178/distance-dependent-fluorescence-quenching-and-enhancement-of-gold-nanoclusters-by-gold-nanoparticles
#9
Haiyan Qin, Diao Ma, Jianxiu Du
The interaction between fluorescent gold nanoclusters (AuNCs) and gold nanoparticles (AuNPs) has been investigated. It was observed that the fluorescence of AuNCs was remarkably quenched when direct contact with AuNPs. The fluorescence quenching of AuNCs by AuNPs was dynamic quenching and exhibited size-dependent property. A larger size of AuNPs displayed a stronger quenching effect and gave a larger quenching constant. When a silica spacer shell was introduced between AuNPs and AuNCs, a fluorescence enhancement of AuNCs by Au@SiO2 NPs was observed...
August 10, 2017: Spectrochimica Acta. Part A, Molecular and Biomolecular Spectroscopy
https://www.readbyqxmd.com/read/28809460/quasi-dual-packed-kerneled-au49-2-4-dmbt-27-nanoclusters-and-the-influence-of-kernel-packing-on-the-electrochemical-gap
#10
Lingwen Liao, Shengli Zhuang, Pu Wang, Yanan Xu, Nan Yan, Hongwei Dong, Chengming Wang, Yan Zhao, Nan Xia, Jin Li, Haiteng Deng, Yong Pei, Shi-Kai Tian, Zhikun Wu
Although face-centered cubic (fcc), body-centered cubic (bcc), hexagonal close-packed (hcp), and other structured gold nanoclusters have been reported, it was unclear whether gold nanoclusters with mix-packed (fcc and non-fcc) kernels exist, and the correlation between kernel packing and the properties of gold nanoclusters is unknown. A Au49 (2,4-DMBT)27 nanocluster with a shell electron count of 22 has now been been synthesized and structurally resolved by single-crystal X-ray crystallography, which revealed that Au49 (2,4-DMBT)27 contains a unique Au34 kernel consisting of one quasi-fcc-structured Au21 and one non-fcc-structured Au13 unit (where 2,4-DMBTH=2,4-dimethylbenzenethiol)...
August 15, 2017: Angewandte Chemie
https://www.readbyqxmd.com/read/28806062/exploring-strategies-for-labeling-viruses-with-gold-nanoclusters-through-non-equilibrium-molecular-dynamics-simulations
#11
Emmi Pohjolainen, Sami Malola, Gerrit Groenhof, Hannu Häkkinen
Biocompatible gold nanoclusters can be utilized as contrast agents in virus imaging. The labeling of viruses can be achieved noncovalently but site-specifically by linking the cluster to the hydrophobic pocket of a virus via a lipid-like pocket factor. We have estimated the binding affinities of three different pocket factors of echovirus 1 (EV1) in molecular dynamics simulations combined with non-equilibrium free-energy calculations. We have also studied the effects on binding affinities with a pocket factor linked to the Au102pMBA44 nanocluster in different protonation states...
August 29, 2017: Bioconjugate Chemistry
https://www.readbyqxmd.com/read/28805392/photoinduced-ultrafast-charge-transfer-and-charge-migration-in-small-gold-clusters-passivated-by-a-chromophoric-ligand
#12
Valérie Schwanen, Francoise Remacle
Because the development of attopulses, charge migration induced by short optical pulses has been extensively investigated. We report a computational purely electronic dynamical study of ultrafast few femtoseconds (fs) charge transfer and charge migration in realistic passivated stoichiometric Au11 and Au20 gold nanoclusters functionalized by a bipyridine ligand. We show that a net significant amount of electronic charge (0.1 to 0.4 |e| where |e| is the electron charge) is permanently transferred from the bipyridine chromophore to the gold cluster during the short 5-6 fs UV-vis strong pulse...
September 13, 2017: Nano Letters
https://www.readbyqxmd.com/read/28800705/two-photon-imaging-of-3d-organization-of-bimetallic-auag-nanoclusters-in-dna-matrix
#13
Katarzyna Brach, Magdalena Waszkielewicz, Joanna Olesiak-Banska, Marek Samoc, Katarzyna Matczyszyn
We report on two-photon excitation properties of small silver-doped gold nanoclusters (AuAgNCs) and on their three-dimensional arrangement in a hybrid system composed of DNA liquid crystals (LCs) and AuAgNCs. UV-vis and fluorescence spectroscopy, transmission electron microscopy (TEM), and multiphoton excitation spectroscopy were used to characterize the nanoparticles. We show that AuAgNCs exhibit two-photon excited luminescence (2PL) emission and second-harmonic generation (SHG) and that these properties remain the same in liquid crystalline matrix...
August 24, 2017: Langmuir: the ACS Journal of Surfaces and Colloids
https://www.readbyqxmd.com/read/28796513/evolution-of-excited-state-dynamics-in-periodic-au28-au36-au44-and-au52-nanoclusters
#14
Meng Zhou, Chenjie Zeng, Matthew Y Sfeir, Mircea Cotlet, Kenji Iida, Katsuyuki Nobusada, Rongchao Jin
Understanding the correlation between the atomic structure and optical properties of gold nanoclusters is essential for exploration of their functionalities and applications involving light harvesting and electron transfer. We report the femto-nanosecond excited state dynamics of a periodic series of face-centered cubic (FCC) gold nanoclusters (including Au28, Au36, Au44, and Au52), which exhibit a set of unique features compared with other similar sized clusters. Molecular-like ultrafast Sn → S1 internal conversions (i...
August 15, 2017: Journal of Physical Chemistry Letters
https://www.readbyqxmd.com/read/28778031/transformation-from-gold-nanoclusters-to-plasmonic-nanoparticles-a-general-strategy-towards-selective-detection-of-organophosphorothioate-pesticides
#15
Qian Lu, Tingyao Zhou, Yaping Wang, Lingshan Gong, Jinbin Liu
Luminescent gold nanoclusters (AuNCs) synthesized using non-thiolate DNA ligands were reported to show both optical and structure responses toward diethyposphorthioate (DEP) derived from the hydrolysis of chlorpyrifos (CP). After incubation of AuNCs with DEP, the non-thiolate DNA ligands were immediately replaced and the tiny AuNCs with ultrasmall size transformed gradually to plasmonic nanoparticles, which resulted in significant luminescence quenching of the AuNCs, offering a new possibility to selectively detect organophosphorothioate pesticides that could be easily hydrolyzed to form the special structures such as DEP containing two binding sites (e...
July 29, 2017: Biosensors & Bioelectronics
https://www.readbyqxmd.com/read/28774954/ballistic-thermophoresis-of-adsorbates-on-free-standing-graphene
#16
Emanuele Panizon, Roberto Guerra, Erio Tosatti
The textbook thermophoretic force which acts on a body in a fluid is proportional to the local temperature gradient. The same is expected to hold for the macroscopic drift behavior of a diffusive cluster or molecule physisorbed on a solid surface. The question we explore here is whether that is still valid on a 2D membrane such as graphene at short sheet length. By means of a nonequilibrium molecular dynamics study of a test system-a gold nanocluster adsorbed on free-standing graphene clamped between two temperatures [Formula: see text] apart-we find a phoretic force which for submicron sheet lengths is parallel to, but basically independent of, the local gradient magnitude...
August 22, 2017: Proceedings of the National Academy of Sciences of the United States of America
https://www.readbyqxmd.com/read/28772077/efficient-electrosteric-assembly-of-nanoparticle-heterodimers-and-linear-heteroassemblies
#17
Ryan Kastilani, Ryan Wong, Lilo D Pozzo
Bottom-up approaches to the synthesis of nanostructures are of particular interest because they offer several advantages over the traditional top-down approaches. In this work, we present a new method to self-assemble nanoparticles into controlled heteroaggregates. The technique relies on carefully balancing attractive electrostatic forces with repulsive steric hindrance that is provided by surface-grafted polyethylene glycol (PEG). Two different-sized gold nanoparticles (GNPs) were used as a model system: 13 nm GNPs were functionalized with PEG-thiol and mercapto dodecanoic acid, while 7 nm GNPs were functionalized with PEG-thiol and (11- Mercaptoundecyl)trimethylammonium bromide...
August 23, 2017: Langmuir: the ACS Journal of Surfaces and Colloids
https://www.readbyqxmd.com/read/28758713/in-situ-assembly-of-au-nanoclusters-within-protein-hydrogel-networks
#18
Liqiang Wang, Xingxing Jiang, Min Zhang, Minghui Yang, You-Nian Liu
We report a new approach of in situ assembling gold nanoclusters (AuNCs) into hydrogel networks by exploiting the triple roles of protein as a gelator, a reducing agent as well as a template. The strategy simply involves the mixing of BSA and AuCl4(-) under alkaline condition. The obtained AuNCs-protein nanocomposite hydrogels with injectable and moldable features can be made into semi-transparent films or N-doped C/Au composites. Our work demonstrates the feasibility of fabricating AuNCs in situ embedded in hybrid hydrogels, which can serve as multifunctional precursors for constructing diverse nanocomposite materials...
July 31, 2017: Chemistry, An Asian Journal
https://www.readbyqxmd.com/read/28750241/a-polypeptide-mediated-synthesis-of-green-fluorescent-gold-nanoclusters-for-fe-3-sensing-and-bioimaging
#19
Hua Li, Hong Huang, Jiu-Ju Feng, Xiliang Luo, Ke-Ming Fang, Zhi-Gang Wang, Ai-Jun Wang
In this paper, growth hormone releasing peptide-6 (GHRP-6) is a bioactive polypeptide and acts as the reducing agent and capping ligand for synthesis of bright green fluorescent gold nanoclusters (GHRP-6-Au NCs) by a simple and environmental-friendly aqueous method, with the assistance of NaBr as the fluorescent sensitizer. The obtained GHRP-6-Au NCs had high fluorescent quantum yield (10.7%), and the fluorescence was strongly quenched by the existence of trace Fe(3+). Thus, a new and highly sensitive sensor for the assay of Fe(3+) was constructed based on the analyte-induced fluorescent quenching mechanism...
November 15, 2017: Journal of Colloid and Interface Science
https://www.readbyqxmd.com/read/28741296/homoleptic-alkynyl-protected-gold-nanoclusters-au44-phc%C3%A2-c-28-and-au36-phc%C3%A2-c-24
#20
Xian-Kai Wan, Zong-Jie Guan, Quan-Ming Wang
For the first time total structure determination of homoleptic alkynyl-protected gold nanoclusters is reported. The nanoclusters are synthesized by direct reduction of PhC≡CAu, to give Au44 (PhC≡C)28 and Au36 (PhC≡C)24 . The Au44 and Au36 nanoclusters have fcc-type Au36 and Au28 kernels, respectively, as well as surrounding PhC≡C-Au-C2 (Ph)Au-C≡CPh dimeric "staples" and simple PhC≡C bridges. The structures of Au44 (PhC≡C)28 and Au36 (PhC≡C)24 are similar to Au44 (SR)28 and Au36 (SR)24 , but the UV/Vis spectra are different...
September 11, 2017: Angewandte Chemie
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