CAS Wuhan Center for Magnetic Resonance

Wuhan, China

CAS Wuhan Center for Magnetic Resonance

Wuhan, China
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Liu C.,CAS Institute of Chemistry | Gao Z.,Jilin University | Zeng J.,CAS Institute of Chemistry | Hou Y.,CAS Institute of Chemistry | And 7 more authors.
ACS Nano | Year: 2013

Detection of early malignant tumors remains clinically difficult; developing ultrasensitive imaging agents is therefore highly demanded. Owing to the unusual magnetic and optical properties associated with f-electrons, rare-earth elements are very suitable for creating functional materials potentially useful for tumor imaging. Nanometer-sized particles offer such a platform with which versatile unique properties of the rare-earth elements can be integrated. Yet the development of rare-earth nanoparticle-based tumor probes suitable for imaging tiny tumors in vivo remains difficult, which challenges not only the physical properties of the nanoparticles but also the rationality of the probe design. Here we report new approaches for size control synthesis of magnetic/upconversion fluorescent NaGdF4:Yb,Er nanocrystals and their applications for imaging tiny tumors in vivo. By independently varying F-:Ln3+ and Na+:Ln3+ ratios, the size and shape regulation mechanisms were investigated. By replacing the oleic acid ligand with PEG2000 bearing a maleimide group at one end and two phosphate groups at the other end, PEGylated NaGdF4:Yb,Er nanoparticles with optimized size and upconversion fluorescence were obtained. Accordingly, a dual-modality molecular tumor probe was prepared, as a proof of concept, by covalently attaching antitumor antibody to PEGylated NaGdF4:Yb,Er nanoparticles through a "click" reaction. Systematic investigations on tumor detections, through magnetic resonance imaging and upconversion fluorescence imaging, were carried out to image intraperitoneal tumors and subcutaneous tumors in vivo. Owing to the excellent properties of the molecular probes, tumors smaller than 2 mm was successfully imaged in vivo. In addition, pharmacokinetic studies on differently sized particles were performed to disclose the particle size dependent biodistributions and elimination pathways. © 2013 American Chemical Society.


Zhang Y.,Nanjing Southeast University | Zhang W.,Nanjing Southeast University | Li S.-H.,CAS Wuhan Center for Magnetic Resonance | Ye Q.,Nanjing Southeast University | And 4 more authors.
Journal of the American Chemical Society | Year: 2012

A novel mononuclear metal-organic compound, [Cu(Hdabco)(H 2O)Cl 3] (1, dabco = 1,4-diazabicyclo[2.2.2]octane) in which the Cu II cation adopts a slightly distorted bipyramidal geometry where the three Cl anions constitute the equatorial plane and the Hdabco cation and H 2O molecule occupy the two axial positions, was synthesized. Its paraelectric-to-ferroelectric phase transition at 235 K (T c) and dynamic behaviors were characterized by single crystal X-ray diffraction analysis, thermal analysis, dielectric and ferroelectric measurements, second harmonic generation experiments, and solid-state nuclear magnetic resonance measurements. Compound 1 behaves as a molecular rotor above room temperature in which the (Hdabco) part rotates around the N•••N axis as a rotator and the [Cu(H 2O)Cl 3] part acts as a stator. In the temperature range 235-301 K, a twisting motion of the rotator is confirmed. Below the T c, the motions of the rotor are frozen and the molecules become ordered, corresponding to a ferroelectric phase. Origin of the ferroelectricity was ascribed to relative movements of the anions and cations from the equilibrium position, which is induced by the order-disorder transformation of the twisting motion of the molecule between the ferroelectric and paraelectric phases. Study of the deuterated analogue [Cu(Ddabco)(D 2O)Cl 3] (2) excludes the possibility of proton ordering as the origin of the ferroelectricity in 1. © 2012 American Chemical Society.


Theillet F.-X.,Leibniz Institute for Molecular Pharmacology | Binolfi A.,Leibniz Institute for Molecular Pharmacology | Frembgen-Kesner T.,University of Iowa | Hingorani K.,University of Massachusetts Amherst | And 9 more authors.
Chemical Reviews | Year: 2014

The unrelated protein Sup35p acts as a release factor during translation termination, and its activity is lost upon amyloid formation. Once Sup35p aggregates, RNA polymerase reads through stop codons, which results in greater protein diversity and the generation of new protein activities that are beneficial for survival. Aggregation of Ure2p and Sup35p are mediated by their disordered, asparagine- and glutamine-rich N-termini. Research into disordered proteins produced significant findings and established important new concepts. On the structural side, novel experimental and computational approaches identified and described disordered protein ensembles and led to terms such as secondary structure propensities, residual structural features, and transient longrange contacts.


Feng N.,CAS Wuhan Center for Magnetic Resonance | Wang Q.,CAS Wuhan Center for Magnetic Resonance | Zheng A.,CAS Wuhan Center for Magnetic Resonance | Zhang Z.,CAS Wuhan Center for Magnetic Resonance | And 4 more authors.
Journal of the American Chemical Society | Year: 2013

The origin of the exceptionally high activity of (B, Ag)-codoped TiO 2 catalysts under solar-light irradiation has been investigated by XPS and 11B solid-state NMR spectroscopy in conjunction with density functional theory (DFT) calculations. XPS experimental results demonstrated that a portion of the dopant Ag (Ag3+) ions were implanted into the crystalline lattice of (B, Ag)-codoped TiO2 and were in close proximity to the interstitial B (Bint.) sites, forming [B int.-O-Ag] structural units. In situ XPS experiments were employed to follow the evolution of the chemical states of the B and Ag dopants during UV-vis irradiation. It was found that the [Bint.-O-Ag] units could trap the photoinduced electron to form a unique intermediate structure in the (B, Ag)-codoped TiO2 during the irradiation, which is responsible for the photoinduced shifts of the B 1s and Ag 3d peaks observed in the in situ XPS spectra. Solid-state NMR experiments including 11B triple-quantum and double-quantum magic angle spinning (MAS) NMR revealed that up to six different boron species were present in the catalysts and only the tricoordinated interstitial boron (T) species was in close proximity to the substitutional Ag species, leading to formation of [T-O-Ag] structural units. Furthermore, as demonstrated by DFT calculations, the [T-O-Ag] structural units were responsible for trapping the photoinduced electrons, which prolongs the life of the photoinduced charge carriers and eventually leads to a remarkable enhancement in the photocatalytic activity. All these unprecedented findings are expected to be crucial for understanding the roles of B and Ag dopants and their synergistic effect in numerous titania-mediated photocatalytic reactions. © 2013 American Chemical Society.


Wang W.,CAS Lanzhou Institute of Chemical Physics | Wang W.,University of Chinese Academy of Sciences | Zheng A.,CAS Wuhan Center for Magnetic Resonance | Zhao P.,CAS Lanzhou Institute of Chemical Physics | And 3 more authors.
ACS Catalysis | Year: 2014

The synthetic control and functions of porous organic polymers (POPs) with N-heterocyclic carbene gold(I) (Au-NHC@POPs) are described in this article. A series of Au-NHC@POPs with tunable physical properties such as surface area and pore size distribution were first synthesized via Sonogashira chemistry by differing monomer strut lengths and concentration during polymerization; a controllable transition from nonporous to microporous and the coexistence of micro- and mesoporous structures in the framework were realized by varying the monomer concentration. To explain this phenomenon, we put forward a model assumption of a branch-branch cross effect. Additionally, Au-NHC@POPs1 was found to have superior catalytic activity in alkyne hydration reactions, and the catalyst could be used six times with a slight loss of activity. © 2013 American Chemical Society.


Jiang B.,University of New Mexico | Liu R.,CAS Wuhan Center for Magnetic Resonance | Li J.,University of New Mexico | Xie D.,Nanjing University | And 2 more authors.
Chemical Science | Year: 2013

Dissociative chemisorption of CH4 on transition-metal surfaces, representing the rate-limiting step in methane steam reforming, has been shown experimentally to be strongly mode selective. To understand the mode selectivity, a twelve-dimensional global potential energy surface is developed for CH4 interacting with a rigid Ni(111) surface based on a large number of density functional theory points. The reaction dynamics is investigated using an eight-dimensional quantum model, which includes representatives of all four vibrational modes of methane. After correcting for surface effects, key experimental observations, including the mode selectivity, are well reproduced. These theoretical results, along with mechanistic analysis, provide insights into this industrially important heterogeneous reaction. © 2013 The Royal Society of Chemistry.


Sun Z.,CAS Fujian Institute of Research on the Structure of Matter | Luo J.,CAS Fujian Institute of Research on the Structure of Matter | Zhang S.,CAS Fujian Institute of Research on the Structure of Matter | Ji C.,CAS Fujian Institute of Research on the Structure of Matter | And 4 more authors.
Advanced Materials | Year: 2013

Exceptional nonlinear optical (NLO) switching behavior, including an extremely large contrast (on/off) of ∼35 and high NLO coefficients, is displayed by a solid-state reversible quadratic NLO switch. The favorable results, induced by very fast molecular motion and anionic ordering, provides impetus for the design of a novel second-harmonic-generation switch involving molecular motion. Copyright © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.


Niu Z.,CAS Wuhan Center for Magnetic Resonance | Zhao W.,CAS Wuhan Center for Magnetic Resonance | Zhang Z.,CAS Wuhan Center for Magnetic Resonance | Xiao F.,CAS Wuhan Center for Magnetic Resonance | And 2 more authors.
Angewandte Chemie - International Edition | Year: 2014

β-amyloid (Aβ) fibrils are the major species involved in Alzheimer's disease (AD). An atomic-resolution molecular structure of Aβ40 fibrils formed in the presence of lipid vesicles was obtained by using magic angle spinning (MAS) solid-state NMR spectroscopy. The fibril structures formed in the presence of the lipid vesicles are remarkably different from those formed in solution. These results provide insights into the molecular mechanism of Aβ aggregation in the presence of lipid vesicles. Fickle fibers: An atomic-resolution molecular structure of β-amyloid fibrils formed in the presence of lipid vesicles was obtained by using highly ordered fibril samples and multidimensional solid-state NMR (monomeric unit shown). The structure of the fibrils formed in the presence of lipid vesicles is different from those formed in solution. This study provides new structural insights into the molecular mechanism of Aβ aggregation. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.


Li J.,CAS Wuhan Center for Magnetic Resonance | Pilla K.B.,Australian National University | Li Q.,Nankai University | Zhang Z.,CAS Wuhan Center for Magnetic Resonance | And 3 more authors.
Journal of the American Chemical Society | Year: 2013

Magic angle spinning solid-state NMR is a unique technique to study atomic-resolution structure of biomacromolecules which resist crystallization or are too large to study by solution NMR techniques. However, difficulties in obtaining sufficient number of long-range distance restraints using dipolar coupling based spectra hamper the process of structure determination of proteins in solid-state NMR. In this study it is shown that high-resolution structure of proteins in solid phase can be determined without the use of traditional dipolar-dipolar coupling based distance restraints by combining the measurements of pseudocontact shifts (PCSs) with Rosetta calculations. The PCSs were generated by chelating exogenous paramagnetic metal ions to a tag 4-mercaptomethyl-dipicolinic acid, which is covalently attached to different residue sites in a 56-residue immunoglobulin-binding domain of protein G (GB1). The long-range structural restraints with metal-nucleus distance of up to ∼20 Å are quantitatively extracted from experimentally observed PCSs, and these are in good agreement with the distances back-calculated using an X-ray structure model. Moreover, we demonstrate that using several paramagnetic ions with varied paramagnetic susceptibilities as well as the introduction of paramagnetic labels at different sites can dramatically increase the number of long-range restraints and cover different regions of the protein. The structure generated from solid-state NMR PCSs restraints combined with Rosetta calculations has 0.7 Å root-mean-square deviation relative to X-ray structure. © 2013 American Chemical Society.


Yu Z.,CAS Wuhan Center for Magnetic Resonance | Zheng A.,CAS Wuhan Center for Magnetic Resonance | Wang Q.,CAS Wuhan Center for Magnetic Resonance | Chen L.,CAS Wuhan Center for Magnetic Resonance | And 3 more authors.
Angewandte Chemie - International Edition | Year: 2010

A zeolite dealumination mechanism is proposed on the basis of sensitivity-enhanced 27Al DQ-MAS NMR spectra (see picture), which revealed for the first time the detailed evolution of extra-framework aluminum (EFAL) species and the spatial proximities of various aluminum species in dealuminated HY zeolites. Three types of EFAL species in close proximity to framework aluminum were identified. © 2010 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

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