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1.
Proc Natl Acad Sci U S A ; 118(47)2021 11 23.
Artigo em Inglês | MEDLINE | ID: mdl-34789566

RESUMO

We report a molecular switching ensemble whose states may be regulated in synergistic fashion by both protonation and photoirradiation. This allows hierarchical control in both a kinetic and thermodynamic sense. These pseudorotaxane-based molecular devices exploit the so-called Texas-sized molecular box (cyclo[2]-(2,6-di(1H-imidazol-1-yl)pyridine)[2](1,4-dimethylenebenzene); 14+, studied as its tetrakis-PF6- salt) as the wheel component. Anions of azobenzene-4,4'-dicarboxylic acid (2H+•2) or 4,4'-stilbenedicarboxylic acid (2H+•3) serve as the threading rod elements. The various forms of 2 and 3 (neutral, monoprotonated, and diprotonated) interact differently with 14+, as do the photoinduced cis or trans forms of these classic photoactive guests. The net result is a multimodal molecular switch that can be regulated in synergistic fashion through protonation/deprotonation and photoirradiation. The degree of guest protonation is the dominating control factor, with light acting as a secondary regulatory stimulus. The present dual input strategy provides a complement to more traditional orthogonal stimulus-based approaches to molecular switching and allows for the creation of nonbinary stimulus-responsive functional materials.

2.
J Am Chem Soc ; 145(16): 8954-8964, 2023 04 26.
Artigo em Inglês | MEDLINE | ID: mdl-37029734

RESUMO

Mechanical interactions between cells and extracellular matrix (ECM) are critical for stem cell fate decision. Synthetic models of ECM, such as hydrogels, can be used to precisely manipulate the mechanical properties of the cell niche and investigate how mechanical signals regulate the cell behavior. However, it has long been a great challenge to tune solely the ECM-mimic hydrogels' mechanical signals since altering the mechanical properties of most materials is usually accompanied by chemical and topological changes. Here, we employ DNA and its enantiomers to prepare a series of hydrogels with univariate stiffness regulation, which enables a precise interpretation of the fate decision of neural progenitor cells (NPCs) in a three-dimensional environment. Using single-cell RNA sequencing techniques, Monocle pseudotime trajectory and CellphoneDB analysis, we demonstrate that the stiffness of the hydrogel alone does not influence the differentiation of NPCs, but the degradation of the hydrogel that enhances cell-cell interactions is possibly the main reason. We also find that ECM remodeling facilitates cells to sense mechanical stimuli.


Assuntos
Hidrogéis , Transcriptoma , Hidrogéis/química , Matriz Extracelular/metabolismo , Células-Tronco , DNA/metabolismo
3.
Langmuir ; 39(12): 4537-4543, 2023 Mar 28.
Artigo em Inglês | MEDLINE | ID: mdl-36926892

RESUMO

By combining DNA nanotechnology and solid-phase nanopore technology, the aggregation behavior of polymer guided by a single-molecular poly(propylene) (PPO) nucleus in a 3D DNA network has been studied. At low temperature, the PPO chain is evenly dispersed in the rigid 3D DNA network; at higher temperature, the PPO chain self-collapses to a single-molecular nucleus; and upon addition of amphiphilic block copolymers below the critical micelle concentration (CMC), the chains tend to aggregate on the isolated hydrophobic nucleus through intermolecular hydrophobic interactions. The process has been characterized by a rheological test and an electrochemical test. This study not only provides a preliminary understanding of the nucleation and growth process of block copolymers but also offers a theoretical basis for the study of protein self-folding and aggregation in the future. On this basis, utilizing this nucleation and growth event, a novel smart nanopore has been developed for hydrophobicity-dependent molecular transport.

4.
Acta Radiol ; 64(2): 798-805, 2023 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-35306860

RESUMO

BACKGROUND: Coronary artery distension and aneurysm are complications of Kawasaki disease in children. PURPOSE: To develop a Z-score regression model for coronary artery diameter in children that could be used as reference. MATERIAL AND METHODS: This retrospective analysis included children with normal heart structure between March 2013 and April 2017. Body surface area (BSA) was calculated. The diameters of the right coronary, left main coronary, left anterior descending, and circumflex arteries were measured by echocardiography. Pearson correlation analysis was used to establish linear, exponential, logarithmic, power, and square root regression models. RESULTS: The analysis included 509 children (280 boys) aged 1 day to 15.2 years. Coronary artery diameters were significantly correlated with age, height, body mass, BSA, and BSA (r = 0.663-0.826; P < 0.05), with a stronger correlation for BSA than BSA (P < 0.05). The adjusted determination coefficients (Ra2) were higher for the exponential and square root models than for the other models (P < 0.05). The random error term variance was constant for the exponential model (P > 0.05), and processing with the weighted least-square methods eliminated heteroscedasticity in the other models. The Z-scores were normally distributed for the exponential and square root models (P > 0.05). CONCLUSION: Overall, the square root model was the optimal equation for the calculation of coronary artery Z-score in Chinese Han children. This model could be used to facilitate the diagnosis of coronary artery distension in children with suspected Kawasaki disease.


Assuntos
Vasos Coronários , Síndrome de Linfonodos Mucocutâneos , Criança , Humanos , Lactente , Masculino , Vasos Coronários/diagnóstico por imagem , Vasos Coronários/anatomia & histologia , População do Leste Asiático , Ecocardiografia/métodos , Síndrome de Linfonodos Mucocutâneos/complicações , Síndrome de Linfonodos Mucocutâneos/diagnóstico por imagem , Estudos Retrospectivos , Feminino , Recém-Nascido , Pré-Escolar , Adolescente
5.
Angew Chem Int Ed Engl ; 62(32): e202305449, 2023 Aug 07.
Artigo em Inglês | MEDLINE | ID: mdl-37338222

RESUMO

Recent years have witnessed marked progress in the efficient synthesis of various enantioenriched 1,2,3,4-tetrahydroquinoxalines. However, enantio- and diastereoselective access to trans-2,3-disubstituted 1,2,3,4-tetrahydroquinoxalines remains much less explored. Herein we report that a frustrated Lewis pair-based catalyst generated via in situ hydroboration of 2-vinylnaphthalene with HB(C6 F5 )2 allows for the one-pot tandem cyclization/hydrosilylation of 1,2-diaminobenzenes and 1,2-diketones with commercially available PhSiH3 to exclusively afford trans-2,3-disubstituted 1,2,3,4-tetrahydroquinoxalines in high yields with excellent diastereoselectivities (>20 : 1 dr). Furthermore, this reaction can be rendered asymmetric by using an enantioenriched borane-based catalyst derived from HB(C6 F5 )2 and a binaphthyl-based chiral diene to give rise to enantioenriched trans-2,3-disubstituted 1,2,3,4-tetrahydroquinoxalines in high yields with almost complete diastereo- and enantiocontrol (>20 : 1 dr, up to >99 % ee). A wide substrate scope, good tolerance of diverse functionality and up to 20-gram scale production are demonstrated. The enantio- and diastereocontrol are achieved by the judicious choice of borane catalyst and hydrosilane. The catalytic pathway and the origin of the excellent stereoselectivity are elucidated by mechanistic experiments and DFT calculations.

6.
Chemistry ; 28(36): e202200441, 2022 Jun 27.
Artigo em Inglês | MEDLINE | ID: mdl-35388545

RESUMO

The first RhI -catalyzed, directed decarbonylative C2-H alkenylation of imidazoles with readily available alkenyl carboxylic acids is reported. The reaction proceeds in a highly regio- and stereoselective manner, providing efficient access to C2-alkenylated imidazoles that are generally inaccessible by known C-H alkenylation methods. This transformation accommodates a wide range of alkenyl carboxylic acids, including challenging conjugated polyene carboxylic acids, and diversely decorated imidazoles with high functional group compatibility. The presence of a removable pyrimidine directing group and the use of a bidentate phosphine ligand are pivotal to the success of the catalytic reaction. This process is also suitable for benzimidazoles. Importantly, the scalability and diversification of the products highlight the potential of this protocol in practical applications. Detailed experimental and computational studies provide important insights into the underlying reaction mechanism.


Assuntos
Ácidos Carboxílicos , Imidazóis , Catálise , Ligantes
7.
Org Biomol Chem ; 20(38): 7645-7649, 2022 10 05.
Artigo em Inglês | MEDLINE | ID: mdl-36125438

RESUMO

A Rh(I)-catalyzed trideuteromethylation of heteroarenes with inexpensive and readily available deuterated acetic acid (CD3CO2D) with the aid of a N-containing directing groups is developed. The oxidant-free reaction is applicable to a wide range of heteroarene substrates, including 2-pyridones, indoles, aryl rings, pyrroles and carbazoles. It allows installation of CD3 groups under straightforward reaction conditions. It is expected that the salient and practical features of this trideuteromethylation protocol will be of use to academic and industrial researchers.


Assuntos
Ródio , Carbazóis/química , Catálise , Indóis/química , Piridonas , Pirróis/química , Ródio/química
8.
Opt Express ; 29(3): 3211-3220, 2021 Feb 01.
Artigo em Inglês | MEDLINE | ID: mdl-33770924

RESUMO

Axisymmetric extension of beam steering angles by metasurfaces is of great interest due to its potential application in extending the angular scan range of existing phased arrays. This angle-multiplexed manipulation functionality requires anti-symmetrically angle-dispersive phase gradient, as well as anti-symmetric angular phase dispersion over continuous incident angles, which is difficult to be implemented by existing metasurfaces. In this work, a series of meta-atoms with asymmetric structures are developed to achieve the required phase response. Based on the asymmetric meta-atoms, an angle-dispersive metasurface for axisymmetric beam steering of transmitted transverse-magnetic (TM) wave is designed, fabricated and tested, whose simulation and experimental results demonstrate the axisymmetric extension capability of beam steering angles from -53° ≤ θi ≤ 53° to almost -90° ≤ θt ≤ 90°.

9.
Chemistry ; 27(34): 8811-8821, 2021 Jun 16.
Artigo em Inglês | MEDLINE | ID: mdl-33871117

RESUMO

Cp*Rh(III)-catalyzed chelation-assisted direct C-H bond functionalization of 1-(2-pyridyl)-2-pyridones with internal alkynes that can be controlled to give three different products in good yields has been realized. Depending on the reaction conditions, solvents and additives, the reaction pathway can be switched between alkenylation, alkenylation/directing group migration and rollover annulation. These reaction manifolds allow divergent access to a variety of valuable C6-alkenylated 1-(2-pyridyl)-2-pyridones, (Z)-6-(1,2-diaryl-2-(pyridin-2-yl)vinyl)pyridin-2(1H)-ones and 10H-pyrido[1,2-a][1,8]naphthyridin-10-ones from the same starting materials. These protocols exhibit excellent regio- and stereoselectivity, broad substrate scope, and good tolerance of functional groups. A combination of experimental and computational approaches have been employed to uncover the key mechanistic features of these reactions.


Assuntos
Ródio , Alcinos , Catálise , Piridonas
10.
J Org Chem ; 86(4): 3648-3655, 2021 02 19.
Artigo em Inglês | MEDLINE | ID: mdl-33372518

RESUMO

Three-substituted 4H-quinolizin-4-ones were obtained via a facile method with good selectivity and high efficiency. On the basis of alkyne substrate control, the mild and cost-efficient reaction has a broad substrate scope (20 examples, up to 93% yield) and is also easy to scale up. Active sites on the products allow for further modifications. The alkyne substrate control strategy could be further extended to achieve more complex three-substituted 4H-quinolizin-4-one skeletons.


Assuntos
Alcinos , Estrutura Molecular
11.
Chembiochem ; 21(1-2): 94-97, 2020 01 15.
Artigo em Inglês | MEDLINE | ID: mdl-31659823

RESUMO

The first thermally stable and pH-responsive quadruplex intercalated motif (i-motif) structure formed by l-DNA is presented. Although this l-type i-motif exhibits the same physiochemical properties as its d isomer, its inverted chirality and good enzymatic resistance potentially open the way to the development of new DNA materials of pharmaceutical and biological interest.


Assuntos
DNA/química , Concentração de Íons de Hidrogênio , Conformação de Ácido Nucleico , Motivos de Nucleotídeos , Termodinâmica
12.
J Org Chem ; 83(16): 9561-9567, 2018 08 17.
Artigo em Inglês | MEDLINE | ID: mdl-29874460

RESUMO

Using carbon dioxide as a C1 precursor, here we report relatively simple and cost-effective orthogonal tandem catalysis, namely Ag2O in conjunction with Cs2CO3 serves to promote a multicomponent tandem reaction forming two new C-C and one new C-N bonds. 4 H-Quinolizin-4-ones, key skeletal components in a variety of biologically active molecules, were obtained with yields up to 99%. The present approach features a broad substrate scope and mild reaction conditions and benefits from using cost-effective reaction and catalysts.

13.
Chemistry ; 22(49): 17576-17580, 2016 Dec 05.
Artigo em Inglês | MEDLINE | ID: mdl-27723167

RESUMO

Reactions of trinickel complex of tripodal tris-tacn ligand N(CH2 -m-C6 H4 -CH2 tacn)3 (L, tacn=1,4,7-triazacyclononane) in acetonitrile-methanol solution with and without phosphate led to two complexes of distinct nuclearities, [(NiII Cl)3 (CH3 OH)3 (HPO4 )L](PF6 ) (Ni3 , 1) and [(NiII5 (CN)4 (H2 O)8 Cl)6 L8 ]Cl30 (Ni30 , 2). Ligand L takes upward and downward conformation in the structure of 1 and 2, respectively. It is proposed that phosphate directs the upward conformation of Ni3 L to form 1. In the absence of phosphate, Ni3 L assembles with cyanide ions, which are formed by Ni-catalyzed C-CN bond cleavage of acetonitrile, to give a nano-sized Ni30 cage. Complex 2 represents a discrete truncated octahedron cage assembled with [Ni5 (CN)4 ]6+ squares and large and flexible triangular ligands, which is scarcely observed for self-assembled metal-organic cages. The magnetic properties of 1 and 2 were examined, showing intriguing magnetic properties.

14.
Bioorg Med Chem Lett ; 26(2): 609-612, 2016 Jan 15.
Artigo em Inglês | MEDLINE | ID: mdl-26631315

RESUMO

It is found that G-quadruplexes have important functions in biological systems, such as gene expression. Molecules which can stabilize the G-quadruplex structure may have potential application in regulating the expression of gene. A series of methylazacalix[n]pyridine (n=4, 6, 7, 8, 9) has been tested to stabilize the intermolecular human telomeric G-quadruplex (T12 and H12), intramolecular TBA, c-kit and bcl-2 G-quadruplex by CD denaturation experiments. The results showed that only methylazacalix[6]pyridine (MACP6) can stabilize the intermolecular G-quadruplex formed from the 12bp human telomere. Further studies evidenced that the shape-complementary binding mode was what contributed to the interaction between MACP6 and T12 G-quadruplex.


Assuntos
Calixarenos/farmacologia , DNA/química , Excipientes/farmacologia , Quadruplex G/efeitos dos fármacos , Telômero/efeitos dos fármacos , Dicroísmo Circular , Humanos , Simulação de Acoplamento Molecular , Desnaturação de Ácido Nucleico/efeitos dos fármacos , Telômero/química
15.
J Am Chem Soc ; 137(40): 12966-76, 2015 Oct 14.
Artigo em Inglês | MEDLINE | ID: mdl-26378806

RESUMO

A set of environmentally responsive metal-organic [3]rotaxanes is described. These mechanically interlocked macromolecules may be prepared in quantitative yield via a one-pot procedure involving treatment of a flexible tetracationic macrocycle, known as the Texas-sized molecular box, with tri-1,3,5-benzenetricarboxylate anion and silver cations (Ag(+)). The use of this three-component mixture gives rise to a metal-organic [3]rotaxane via a self-assembly process that occurs under ambient conditions in DMSO-d6 solution. The complex is stable in the presence of excess TFA. However, disassembly of the [3]rotaxane to produce anion-box associated entities may be triggered by adding a competitive counteranionic species (e.g., I(-)). Adding excess Ag(+) serves to reverse this decomplexation process. The nature of the [3]rotaxane complex could be fine-tuned via application of an external stimulus. Increasing the temperature or adding small molecules (e.g., D2O, methanol-d4, acetonitrile-d3, DMF-d7, acetone-d6, or THF-d8) to the initial DMSO-d6 solution induces conformational flipping of the macrocycle within the overall complex (e.g., from limiting chair to chairlike forms). Support for the molecular stimuli responsive nature of the various structures came from solution-phase one- and two-dimensional ((1)H, 1D and 2D NOESY) NMR spectroscopic studies carried out in DMSO-d6. The core metal-linked rotaxane unit was characterized via single-crystal X-ray diffraction analysis. Initial evidence that the present self-assembly process is not limited to the use of the Ag(+) cation came from studies involving Cd(2+); this replacement results in formation of 2D metal-organic rotaxane-containing frameworks (MORFs).

16.
ACS Macro Lett ; 12(6): 745-750, 2023 06 20.
Artigo em Inglês | MEDLINE | ID: mdl-37207332

RESUMO

Nebulized lipid nanoparticles (LNPs) have been considered as potential therapies for genetic disease as well as infectious disease. However, the sensitivity of LNPs to high shear stress during the nebulization process results in loss of the integrity of the nanostructure and the capability of delivering active pharmaceutical ingredients. Herein we have provided a fast extrusion method to prepare liposomes incorporated with a DNA hydrogel (hydrogel-LNPs) to improve the stability of the LNPs. Taking advantage of the good cellular uptake efficiency, we also demonstrated the potential of hydrogel-LNPs in delivering small molecular doxorubicin (Dox) and nucleic acid drugs. This work provides not only highly biocompatible hydrogel-LNPs for aerosol delivery, but also a strategy to regulate the elasticity of LNPs, which will benefit the potential optimization of drug delivery carriers.


Assuntos
Lipossomos , Nanopartículas , Hidrogéis , Sistemas de Liberação de Medicamentos , Portadores de Fármacos/química , Nanopartículas/química , DNA
17.
Langmuir ; 28(4): 1966-70, 2012 Jan 31.
Artigo em Inglês | MEDLINE | ID: mdl-21995619

RESUMO

We report a general approach to bimodify gold nanoparticles (GNPs) with two different DNA strands via DNA template reaction. Two thioctic acid modified DNA strands, one at 5' end and one at 3' end, were attached to GNPs through bivalent thiol-gold bond. By sequence design, assemblies of 5 nm GNPs chains, 10 nm GNPs chains and alternative arrangement of 5 and 10 nm GNPs could be achieved. Gel electrophoresis, transmission electron microscope (TEM), UV-vis spectra were used to characterize the assemblies. It is believed that this new kind of bimodified GNPs with two different DNA strands at different ends would enrich the toolbox of DNA-GNP conjugates and provide diverse selectivity for further assembly.


Assuntos
DNA/química , Ouro/química , Nanopartículas Metálicas/química , Modelos Moleculares , Conformação de Ácido Nucleico
18.
Org Lett ; 24(29): 5397-5401, 2022 Jul 29.
Artigo em Inglês | MEDLINE | ID: mdl-35834612

RESUMO

A one-pot strategy with yields up to 82% was reported to generate 2-(pyridin-2-yl)-2-(3,3a,6-tris(5-pyridin-2-yl)-5-oxohexahydropyrrolo[3,2-b] pyrrol-2(1H)-ylidene)acetonitrile 1a and its derivatives 1b-d. Silica gel promoted quantitative conversion from stable intermediate to 1a within 30 min at room temperature. Finally, four chemical σ bonds and two chiral carbons with high diastereoselectivity were achieved. Compound 1a can act as a novel high selective UV-vis and fluorescence "turn-on" probe for Zn2+ and Cd2+, respond to proton, and show dual-state emission (DSE) characteristics.

19.
Rev Sci Instrum ; 93(5): 054901, 2022 May 01.
Artigo em Inglês | MEDLINE | ID: mdl-35649782

RESUMO

The obscure theory of passive subambient daytime radiative cooling (PSDRC) was deduced in a more understandable way using an arithmetic formula rather than integro-differential equations. Based on two boundary conditions of the equations, an innovative radiative cooler was successfully developed to qualitatively observe PSDRC phenomena and quantitatively characterize the cooling effect and cooling power of radiative cooling coatings (RC coatings). The remarkable subambient temperature reduction over 4.0 °C was successfully achieved in a completely open environment without minimizing the parasitic conduction and convection from the ambient. Prominent PSDRC phenomena could even be observed in such an open environment on very cloudy days, which generally compromise the RC. A much more prominent subambient cooling depression of 10.0 °C was observed when a wind shield was employed to minimize the convection. With suppression of convection, the subambient daytime cooling effect on cloudy days was even more noticeable than that occurred on clear sunny days. The subambient cooling effect was still very remarkable even on clear sunny days in the winter. The average cooling power measured on a clear sunny day was 154.8 ± 9.7 W/m2, corresponding to an average solar irradiance of 680 ± 90 W/m2 with a peak value of ∼820 W/m2. Both the subambient RC effect and the cooling power measured under real weather conditions using the radiative cooler agreed excellently with the theoretical prediction, sufficiently demonstrating the great innovation, validity, and effectiveness of the device.

20.
Chem Soc Rev ; 39(1): 150-5, 2010 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-20023845

RESUMO

After more than twenty years of effort, using DNA to fabricate addressable nanostructures is now a well-established technology. In this tutorial review, we attempt to present an overview of the applications of DNA templates, including its biological significance, the directing of chemical reactions at the molecular level, as well as the placing of nanoparticles and proteins in position.


Assuntos
DNA/biossíntese , DNA/química , Moldes Genéticos , Sequência de Bases , DNA/genética , DNA/metabolismo , Enzimas/metabolismo , Nanoestruturas/química
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