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1.
J Chem Phys ; 156(24): 244109, 2022 Jun 28.
Artigo em Inglês | MEDLINE | ID: mdl-35778067

RESUMO

Polarization transfers are crucial building blocks in magnetic resonance experiments, i.e., they can be used to polarize insensitive nuclei and correlate nuclear spins in multidimensional nuclear magnetic resonance (NMR) spectroscopy. The polarization can be transferred either across different nuclear spin species or from electron spins to the relatively low-polarized nuclear spins. The former route occurring in solid-state NMR can be performed via cross polarization (CP), while the latter route is known as dynamic nuclear polarization (DNP). Despite having different operating conditions, we opinionate that both mechanisms are theoretically similar processes in ideal conditions, i.e., the electron is merely another spin-1/2 particle with a much higher gyromagnetic ratio. Here, we show that the CP and DNP processes can be described using a unified theory based on average Hamiltonian theory combined with fictitious operators. The intuitive and unified approach has allowed new insights into the cross-effect DNP mechanism, leading to better design of DNP polarizing agents and extending the applications beyond just hyperpolarization. We explore the possibility of exploiting theoretically predicted DNP transients for electron-nucleus distance measurements-such as routine dipolar-recoupling experiments in solid-state NMR.

2.
Natl Sci Rev ; 9(2): nwab138, 2022 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-35233287

RESUMO

High-quality colloidal nanocrystals are commonly synthesized in hydrocarbon solvents with alkanoates as the most common organic ligand. Water molecules with an approximately equal number of surface alkanoate ligands are identified at the inorganic-organic interface for all types of colloidal nanocrystals studied, and investigated quantitatively using CdSe nanocrystals as the model system. Carboxylate ligands are coordinated to the surface metal ions and the first monolayer of water molecules is found to bond to the carboxylate groups of alkanoate ligands through hydrogen bonds. Additional monolayer(s) of water molecules can further be adsorbed through hydrogen bonds to the first monolayer of water molecules. The nearly ideal environment for hydrogen bonding at the inorganic-organic interface of alkanoate-coated nanocrystals helps to rapidly and stably enrich the interface-bonded water molecules, most of which are difficult to remove through vacuum treatment, thermal annealing and chemical drying. The water-enriched structure of the inorganic-organic interface of high-quality colloidal nanocrystals must be taken into account in order to understand the synthesis, processing and properties of these novel materials.

3.
Sci Adv ; 8(6): eabm4606, 2022 Feb 11.
Artigo em Inglês | MEDLINE | ID: mdl-35148184

RESUMO

The solid electrolyte interface (SEI) formed on the anode is one of the key factors that determine the life span of sodium metal batteries (SMBs). However, the continuous evolution of SEI during charging/discharging processes complicates the fundamental understanding of its chemistry and structure. In this work, we studied the underlying mechanisms of the protection effect offered by the SEI derived from sodium difluoro(oxalato)borate (NaDFOB). In situ nuclear magnetic resonance (NMR) shows that the prior reduction of DFOB anion contributes to the SEI formation, and it suppresses the decomposition of carbonate solvents. Depth-profiling x-ray photoelectron spectroscopy and high-resolution solid-state NMR reveal that the DFOB anion is gradually turned into borate and fluoride-rich SEI with cycling. The protection effect of SEI reaches the optimum at 50 cycles, which triples the life span of SMB. The detailed investigations provide valuable guidelines for the SEI engineering.

4.
ACS Appl Mater Interfaces ; 14(4): 5338-5345, 2022 Feb 02.
Artigo em Inglês | MEDLINE | ID: mdl-35050576

RESUMO

The air-sensitivity of transition metal oxide cathode materials (NaxTMO2, TM: transition metal) is a challenge for their practical application in sodium-ion batteries for large-scale energy storage. However, the deterioration mechanism of NaxTMO2 under ambient air is unclear, which hinders the precise design of air-stable NaxTMO2. Here, we revealed the origin of NaxTMO2 degradation by capturing the initial degradation status and microstructural evolution under ambient atmospheres with optimal humidity. It was found that the insertion of CO2 into Na layers along (003) planes of NaxTMO2 led to initial growth of Na2CO3 nanoseeds between TM layers, which initiated fast structure degradation with surface cracks and extrusion of Na2CO3 out of NaxTMO2. The degradation extents and pathways for NaxTMO2 could be highly associated with crystal orientation, particle morphology, and ambient humidity. Interestingly, the deteriorated NaxTMO2 could be completely healed through optimal recalcination, showing even improved air-stability and electrochemical performance. This work provides a helpful perspective on the interfacical structure design of high-performance NaxTMO2 cathodes for sodium-ion batteries.

5.
ACS Appl Mater Interfaces ; 13(20): 23743-23750, 2021 May 26.
Artigo em Inglês | MEDLINE | ID: mdl-34000178

RESUMO

The growing demand for safer energy storage devices leads to wide research on solid-state lithium-ion batteries. However, as an important component in the solid-state battery, the solid-state electrolyte often encounters problems, especially the low conductivity at room temperature, inhibiting the development of solid-state batteries. Here, improved electrochemical performances of lithium-ion batteries are obtained by designing a composite gel polymer electrolyte with a sponge-like structure. The porous composite gel polymer electrolyte (PCGPE) is developed by a facile phase inversion process of poly(vinylidiene fluoride-hexafluoropropylene) (PVdF-HFP) and Li6.4La3Zr1.4Ta0.6O12 (LLZTO). The solid-state nuclear magnetic resonance test proves the continuous porous structure constructs fast Li-ion transport pathways on internal interfaces. As a result, the ionic conductivity of PCGPE is up to 5.45 × 10-4 S cm-1 at room temperature. Moreover, an initial capacity of 142.2 mAh g-1 and 82.6% capacity retention at 1 C after 350 cycles are successfully achieved in flexible LiFPO4//PCGPE//Li batteries.

6.
ACS Biomater Sci Eng ; 7(3): 1159-1168, 2021 03 08.
Artigo em Inglês | MEDLINE | ID: mdl-33617226

RESUMO

The crystallites of calcium phosphate (CaP) in bones consist of hydroxyl apatite (HA) and amorphous calcium phosphate (ACP). These nanoscale structures of CaP are sculptured by biological bone formation and resorption processes and are one of the crucial factors that determine the overall strength of the constructs. We used one- and two-dimensional 1H-31P solid-state nuclear magnetic resonance (SSNMR) to investigate the nanoscopic structural changes of CaP. Two quantitative measurables are deduced based on the heterogeneous linewidth of 31P signal and the ratio of ACP to HA, which characterize the mineral crystallinity and the relative proportion of ACP, respectively. We analyzed bones from different murine models of osteopetrosis and osteoporosis and from human samples with osteoporosis and osteoarthritis. It shows that the ACP content increases notably in osteopetrotic bones that are characterized by defective osteoclastic resorption, whereas the overall crystallinity increases in osteoporotic bones that are marked by overactive osteoclastic resorption. Similar pathological characteristics are observed for the sclerotic bones of late-stage osteoarthritis, as compared to those of the osteopetrotic bones. These findings suggest that osteoclast-related bone diseases not only alter the bone density macroscopically but also lead to abnormal formation of CaP crystallites. The quantitative measurement by SSNMR provides a unique perspective on the pathology of bone diseases at the nanoscopic level.


Assuntos
Fosfatos de Cálcio , Fosfatos , Animais , Osso e Ossos/diagnóstico por imagem , Humanos , Espectroscopia de Ressonância Magnética , Camundongos , Osteoclastos
7.
Angew Chem Int Ed Engl ; 60(14): 7719-7727, 2021 03 29.
Artigo em Inglês | MEDLINE | ID: mdl-33400342

RESUMO

Understanding of drug-carrier interactions is essential for the design and application of metal-organic framework (MOF)-based drug-delivery systems, and such drug-carrier interactions can be fundamentally different for MOFs with or without defects. Herein, we reveal that the defects in MOFs play a key role in the loading of many pharmaceuticals with phosphate or phosphonate groups. The host-guest interaction is dominated by the Coulombic attraction between phosphate/phosphonate groups and defect sites, and it strongly enhances the loading capacity. For similar molecules without a phosphate/phosphonate group or for MOFs without defects, the loading capacity is greatly reduced. We employed solid-state NMR spectroscopy and molecular simulations to elucidate the drug-carrier interaction mechanisms. Through a synergistic combination of experimental and theoretical analyses, the docking conformations of pharmaceuticals at the defects were revealed.


Assuntos
Monofosfato de Adenosina/química , Estruturas Metalorgânicas/química , Nanocápsulas/química , Compostos Organometálicos/química , Ácidos Ftálicos/química , Composição de Medicamentos , Liberação Controlada de Fármacos , Conformação Molecular , Simulação de Acoplamento Molecular , Organofosfonatos/química , Fosfatos/química , Porosidade , Propriedades de Superfície
8.
Bioact Mater ; 6(3): 712-720, 2021 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-33005833

RESUMO

Breast cancer bone metastasis poses significant challenge for therapeutic strategies. Inside the metastatic environment, osteoclasts and tumor cells interact synergistically to promote cancer progression. In this study, the proprotein convertase furin is targeted due to its critical roles in both tumor cell invasion and osteoclast function. Importantly, the furin inhibitor is specifically delivered by bone targeting superparamagnetic iron oxide (SPIO) nanoparticles. Our in vitro and in vivo data demonstrate that this system can effectively inhibit both osteoclastic bone resorption and breast cancer invastion, leading to alleviated osteolysis. Therefore, the bone targeting & furin inhibition nanoparticle system is a promising therapeutic and diagnostic strategy for breast cancer bone metastasis.

9.
Compr Rev Food Sci Food Saf ; 19(4): 1397-1419, 2020 07.
Artigo em Inglês | MEDLINE | ID: mdl-33337086

RESUMO

Metal-organic frameworks (MOFs) are porous coordination materials composed of multidentate organic ligands and metal ions or metal clusters. MOFs have the great potential to be utilized in antibacterial materials for biological, environmental, and food antimicrobial fields. In recent years, MOFs have been applied to various antibacterial fields due to their sustained release capability, porosity, and structural flexibility in combination with many chemicals and/or materials (such as nanoparticles, antibiotics, phytochemicals, and polymers). This review offers a detailed summary of the antibacterial applications of MOFs and their composites, focusing on the combination types of MOFs composites and the antibacterial effect in different applications. These applications are illustrated by the examples discussed in this review.


Assuntos
Antibacterianos/farmacologia , Bactérias/efeitos dos fármacos , Estruturas Metalorgânicas/química , Antibacterianos/química , Portadores de Fármacos , Nanoestruturas/química
10.
J Phys Chem Lett ; 11(17): 7167-7176, 2020 Sep 03.
Artigo em Inglês | MEDLINE | ID: mdl-32787305

RESUMO

The guest adsorption phenomena in multicomponent metal-organic frameworks (MOFs) are intricate due to their structural complexities. In this work, we studied two members of the isostructural series of MUF-77 frameworks that consist of long or short alkyl groups. The adsorption of methanol, N,N-dimethylaniline (DMA) and acridine orange (AO) in two structures of MUF-77 has been investigated. 2H solid-state nuclear magnetic resonance (SSNMR) and two-dimensional 1H-13C NMR spectroscopy were used to probe the dynamics of various compartments of MUF-77. Through the analyses of dynamic behavior by SSNMR and molecular dynamics simulations, we elucidate the spatial distribution of guest molecules are nonuniform around different chemical components, in different pore structures, and across different parts of MOF lattice. In addition, we reveal that the framework flexibility of MUF-77 with short alkyl groups is reduced upon guest adsorption yet the framework flexibility of MUF-77 with long alkyl groups increases upon loading with methanol.

11.
ACS Cent Sci ; 6(7): 1037-1039, 2020 Jul 22.
Artigo em Inglês | MEDLINE | ID: mdl-32724837
12.
J Am Chem Soc ; 142(20): 9169-9174, 2020 May 20.
Artigo em Inglês | MEDLINE | ID: mdl-32363870

RESUMO

Crystalline porous materials such as covalent organic frameworks (COFs) are advanced materials to tackle challenges of catalysis and separation in industrial processes. Their synthetic routes often require elevated temperatures, closed systems with high pressure, and long reaction times, hampering their industrial applications. Here we use a traditionally unperceived strategy to assemble highly crystalline COFs by electron beam irradiation with controlled received dosage, contrasting sharply with the previous observation that radiation damages the crystallinity of solids. Such synthesis by electron beam irradiation can be achieved under ambient conditions within minutes, and the process is amendable for large-scale production. The intense and targeted energy input to the reactants leads to new reaction pathways that favor COF formation in nearly quantitative yield. This strategy is applicable not only to known COFs but also to new series of flexible COFs that are difficult to obtain using traditional methods.

13.
Nano Lett ; 20(2): 829-840, 2020 02 12.
Artigo em Inglês | MEDLINE | ID: mdl-31916446

RESUMO

Breast cancer metastases to bone poses a significant challenge for the administration of treatment strategies. The bone microenvironment, metastatic tumor cells, osteoclasts, and tumor-associated macrophages (TAMs) all play crucial and synergistic roles in creating a favorable environment for the proliferation, progression, and survival of the metastatic tumor, which in turn induces osteoclast-mediated bone destruction. In this study, we functionalized immunostimulatory cytosine-phosphate-guanosine (CpG)-loaded metal-organic framework (MOF) nanoparticles with bone targeting capabilities by surface modification with FDA approved antiresorptive bisphosphonate, zoledronic acid (ZOL). The functionalized bone targeting immunostimulatory MOF (BT-isMOF) nanoparticles demonstrates strong binding to calcium phosphate in vitro and exhibits specific targeting and accumulation in bone tissues in vivo. In vitro cellular and biochemical analyses demonstrated that the BT-isMOF nanoparticles could potently inhibit osteoclast formation and concomitantly induce macrophages polarization toward the M1 pro-inflammatory phenotype. Finally, using the intratibial murine model of breast cancer bone metastasis, we showed that the administration of BT-isMOF nanoparticles significantly suppressed osteoclast-mediated bone destruction and enhanced polarization of tumor-resident macrophages to M1 phenotype. Together, our data provides promising evidence for the potential therapeutic application of the BT-isMOF nanoparticles in the treatment of breast cancer bone metastases.


Assuntos
Neoplasias Ósseas/tratamento farmacológico , Neoplasias da Mama/tratamento farmacológico , Estruturas Metalorgânicas/farmacologia , Nanopartículas/química , Animais , Conservadores da Densidade Óssea/química , Conservadores da Densidade Óssea/farmacologia , Neoplasias Ósseas/patologia , Neoplasias Ósseas/secundário , Neoplasias da Mama/patologia , Linhagem Celular Tumoral , Difosfonatos/química , Difosfonatos/farmacologia , Feminino , Humanos , Estruturas Metalorgânicas/química , Camundongos , Oligodesoxirribonucleotídeos/química , Oligodesoxirribonucleotídeos/farmacologia , Osteoclastos/efeitos dos fármacos , Osteólise/tratamento farmacológico , Osteólise/patologia , Macrófagos Associados a Tumor/efeitos dos fármacos , Ácido Zoledrônico/química , Ácido Zoledrônico/farmacologia
14.
Front Neurosci ; 14: 611696, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-33536869

RESUMO

Ischemic lesions could lead to secondary degeneration in remote regions of the brain. However, the spatial distribution of secondary degeneration along with its role in functional deficits is not well understood. In this study, we explored the spatial and connectivity properties of white matter (WM) secondary degeneration in a focal unilateral sensorimotor cortical ischemia rat model, using advanced microstructure imaging on a 14 T MRI system. Significant axonal degeneration was observed in the ipsilateral external capsule and even remote regions including the contralesional external capsule and corpus callosum. Further fiber tractography analysis revealed that only fibers having direct axonal connections with the primary lesion exhibited a significant degeneration. These results suggest that focal ischemic lesions may induce remote WM degeneration, but limited to fibers tied to the primary lesion. These "direct" fibers mainly represent perilesional, interhemispheric, and subcortical axonal connections. At last, we found that primary lesion volume might be the determining factor of motor function deficits.

15.
Magn Reson Chem ; 58(11): 1049-1054, 2020 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-31846098

RESUMO

Pharmaceutical amorphous solid dispersions, a multicomponent system prepared by dispersing drug substances into polymeric matrix via thermal and mechanical processes, represent a major platform to deliver the poorly water-soluble drug. Microscopic properties of drug-polymer contacts play mechanistic roles in manipulating long-term physical stability as well as dissolution profiles. Although solid-state nuclear magnetic resonance has been utilized as an indispensable tool to probe structural details, previous studies are limited to ex situ characterizations. Our work provides likely the first documented example to investigate comelting of ketoconazole and polyacrylic acid, as a model system, in an in situ manner. Their physical mixture is melted and mixed in the solid-state nuclear magnetic resonance rotor under magic angle spinning at up to approximately 400 K. Critical structural events of molecular miscibility and interaction have been successfully identified. These results design and evaluate the instrumental and experimental protocols for real-time characterizations of the comelting of pharmaceutical materials.


Assuntos
Resinas Acrílicas/química , Antifúngicos/química , Cetoconazol/química , Temperatura , Química Farmacêutica , Espectroscopia de Ressonância Magnética , Estrutura Molecular
16.
Angew Chem Int Ed Engl ; 58(49): 17764-17770, 2019 Dec 02.
Artigo em Inglês | MEDLINE | ID: mdl-31591763

RESUMO

Facet-dependent on-surface reactions are systematically studied on zinc-blende CdSe nanoplatelets with atomically-flat {001} basal facets and small yet non-polar side facets. The on-surface half-reactions between the surface Se sites and Cd carboxylates in the solution are qualitatively equivalent to those on the spheroidal counterparts. Conversely, the on-surface half-reactions between the surface Cd sites and the activated Se precursors in solution show a strong facet-dependence, which includes three distinguishable stages. In the first stage, the Se precursors adsorb onto the small and non-polar side facets of the nanoplatelets. The second stage is initiated by the adsorbed Se precursors at the side-basal plane edges and proceeds from the edges to the center of the basal planes in quasi-zeroth-order kinetics. In the third stage, the nanoplatelets are dismantled, which includes the creation of a hole in the middle and a build-up of thick edges.

17.
Nat Commun ; 10(1): 4805, 2019 10 22.
Artigo em Inglês | MEDLINE | ID: mdl-31641182

RESUMO

Materials demonstrating unusual large positive and negative thermal expansion are fascinating for their potential applications as high-precision microscale actuators and thermal expansion compensators for normal solids. However, manipulating molecular motion to execute huge thermal expansion of materials remains a formidable challenge. Here, we report a single-crystal Cu(II) complex exhibiting giant thermal expansion actuated by collective reorientation of imidazoliums. The circular molecular cations, which are rotationally disordered at a high temperature and statically ordered at a low temperature, demonstrate significant reorientation in the molecular planes. Such atypical molecular motion, revealed by variable-temperature single crystal X-ray diffraction and solid-state NMR analyses, drives an exceptionally large positive thermal expansion and a negative thermal expansion in a perpendicular direction of the crystal. The consequent large shape change (~10%) of bulk material, with remarkable durability, suggests that this complex is a strong candidate as a microscale thermal actuating material.

18.
J Am Chem Soc ; 141(39): 15675-15683, 2019 10 02.
Artigo em Inglês | MEDLINE | ID: mdl-31503473

RESUMO

Aliphatic carboxylates are the most common class of surface ligands to stabilize colloidal nanocrystals. The widely used approach to identify the coordination modes between surface cationic sites and carboxylate ligands is based on the empirical infrared (IR) spectroscopic assignment, which is often ambiguous and thus hampers the practical control of surface structures. In this report, multiple techniques based on nuclear magnetic resonance (NMR) and IR spectra are applied to distinguish the different coordination structures in a series of zinc-blende CdSe nanocrystals with unique facet structures, including nanoplatelets dominated with {100} basal planes, hexahedrons with only three types of low-index facets (i.e., {100}, {110}, and {111}), and spheroidal dots without well-defined facets. Interpretation and assignment of NMR and IR signals were assisted by density functional theory (DFT) calculations. In addition to the identification of facet-sensitive bonding modes, the present methods also allow a nondestructive quantification of mixed ligands.

19.
ACS Appl Mater Interfaces ; 11(40): 37256-37262, 2019 Oct 09.
Artigo em Inglês | MEDLINE | ID: mdl-31496216

RESUMO

Facet engineering of anatase TiO2 by controlling the {001} exposure ratio has been the focus of numerous investigations to optimize photocatalytic activity. In particular, an introduction of fluoride ions during the crystal growth has been demonstrated to be very effective and decisive in realizing the facet exposure of the crystals. However, a key role of fluoride ions in stabilizing {001} exposure and improving subsequent photocatalytic activity of anatase TiO2 remains unclear up to date. Herein, a controlled thickness of anatase TiO2 nanosheets has been realized by introducing different amounts of ethanol into a HF acid-assisted hydrothermal reaction. The thinnest nanosheets with a thickness of ∼2.9 nm were evaluated to have the highest H2 production rate of 41.04 mmol·h-1·g-1 under ultraviolet light irradiation, and the corresponding quantum efficiency was determined to be 41.6% (λ = 365 nm). Moreover, it is proved for the first time that fluoride ions are bonded with Ti vacancies on {001} facets, and such defects are crucial for stabilizing the ultrathin nanosheets and improving their electron-hole separation, therefore leading to a highly efficient photocatalytic activity. The findings offer an opportunity to engineer facets and functionality of anatase TiO2 by controlling surface defects.

20.
Nat Commun ; 10(1): 2454, 2019 06 05.
Artigo em Inglês | MEDLINE | ID: mdl-31165734

RESUMO

A typical colloidal nanoparticle can be viewed as a nanocrystal-ligands complex with an inorganic single-crystalline core, the nanocrystal, bonded with a monolayer of organic ligands. The surface chemistry of nanocrystal-ligands complexes is crucial to their bulk properties. However, deciphering the molecular pictures of the nonperiodic and dynamic organic-inorganic interlayer is a grand technical challenge, and this hampers the quantitative perception of their macroscopic phenomena. Here we show that the atomic arrangement on nanocrystal surface and ligand-ligand interactions can be precisely quantified through comprehensive solid-state nuclear magnetic resonance (SSNMR) methodologies. The analyses reveal that the mixed ligands of n-alkanoates on a CdSe nanocrystal segregate in areal partitions and the unique arrangement unlocks their rotational freedom. The mathematical model based on the NMR-derived ligand partition and dynamics successfully predicts the unusual solubility of nanocrystal-ligands complexes with mixed ligands, which is several orders of magnitude higher than that of nanocrystal-ligands complexes with pure ligands.

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