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1.
Nanoscale ; 12(5): 3058-3067, 2020 Feb 07.
Artigo em Inglês | MEDLINE | ID: mdl-31971199

RESUMO

A material with diverse self-assembled morphologies is extremely important and highly desirable because such samples can provide tunable optical and electronic properties, which are critical in applications such as organic photovoltaics, microelectronics and bio-imaging. Moreover, the synthesis and controllable self-assembly of H-shaped bichromophoric perylenediimides (PDIs) are needed to advance these materials in organic photovoltaics, microelectronics and bio-imaging; however, this has remained a great challenge thus far. Here, we successfully synthesize a novel H-shaped bichromophoric PDI Gemini through the palladium-catalyzed coupling reaction. The as-prepared PDI Gemini exhibited unprecedented tunable self-assembly behavior in solution, yielding diverse low-dimensional superstructures, such as one-dimensional (1D) helices, two-dimensional (2D) rectangular nanocrystals, pyramid-shaped parallelograms, ultralarge micro-sheets, and uniform nanospheres, under different self-assembly conditions. Of particular interest, the 2D hierarchical superstructures along with their formation mechanisms represent the first finding in the self-assembly of PDI-based molecules. This study opens a new avenue for tunable self-assembly of conjugated molecules and affords opportunities for the fabrication of novel self-assembled optical and electronic materials based on PDI molecules.

2.
J Org Chem ; 85(1): 101-107, 2020 Jan 03.
Artigo em Inglês | MEDLINE | ID: mdl-31650830

RESUMO

The unexpected synthesis and characterization of imidazole-fused azaacenes are presented. Their optical and electrochemical properties have been investigated and compared with these of previously reported imidazole-fused azaacenes. Application of these two imidazole-fused azaacenes in memory devices showed distinctly different resistive behaviors.

3.
Angew Chem Int Ed Engl ; 58(29): 9696-9711, 2019 Jul 15.
Artigo em Inglês | MEDLINE | ID: mdl-30756463

RESUMO

Organic cocrystals based on noncovalent intermolecular interactions (weak interactions) have aroused interest owing to their unpredicted and versatile chemicophysical properties and their applications. In this Minireview, we highlight recent research on organic cocrystals on reducing the aggregation-caused quenching (ACQ) effect, tuning light emission, ferroelectricity and multiferroics, optical waveguides, and stimuli-responsiveness. We also summarize the progress made in this field including revealing the structure-property relationships and developing unusual properties. Moreover, we provide a discussion on current achievements, limitations and perspectives as well as some directions and inspiration for further investigation on organic cocrystals.

4.
Nat Commun ; 10(1): 169, 2019 01 11.
Artigo em Inglês | MEDLINE | ID: mdl-30635576

RESUMO

The features of well-conjugated and planar aromatic structures make π-conjugated luminescent materials suffer from aggregation caused quenching (ACQ) effect when used in solid or aggregated states, which greatly impedes their applications in optoelectronic devices and biological applications. Herein, we reduce the ACQ effect by demonstrating a facile and low cost method to co-assemble polycyclic aromatic hydrocarbon (PAH) chromophores and octafluoronaphthalene together. Significantly, the solid photoluminescence quantum yield (PLQYs) for the as-resulted four micro/nanococrystals are enhanced by 254%, 235%, 474 and 582%, respectively. Protection from hydrophilic polymer chains (P123 (PEO20-PPO70-PEO20)) endows the cocrystals with superb dispersibility in water. More importantly, profiting from the above-mentioned highly improved properties, nano-cocrystals present good biocompatibility and considerable cell imaging performance. This research provides a simple method to enhance the emission, biocompatibility and cellular permeability of common chromophores, which may open more avenues for the applications of originally non- or poor fluorescent PAHs.


Assuntos
Antracenos/química , Fluorcarbonetos/química , Luminescência , Naftalenos/química , Compostos Policíclicos/química , Humanos , Células MCF-7 , Nanopartículas/análise , Nanopartículas/química , Imagem Óptica
5.
Inorg Chem ; 57(22): 14035-14038, 2018 Nov 19.
Artigo em Inglês | MEDLINE | ID: mdl-30383376

RESUMO

Preparing low-dimensional perovskite materials with novel building units is highly desirable because such materials have already been demonstrated to show unusual physical properties. In this report, we first reported a new and unusual two-dimensional perovskite framework, [B(HIm)4]4Pb13Br38 (1), constructed from novel Lindqvist-type [Pb6Br19]7- nanoclusters. The as-prepared material shows good water resistance and chemical/heat stability. More importantly, 1 has been proven to exhibit temperature/excitation-wavelength-dependent emission. A possible mechanism has been provided.

6.
Chem Asian J ; 13(21): 3185-3189, 2018 Nov 02.
Artigo em Inglês | MEDLINE | ID: mdl-30199149

RESUMO

Searching novel haloplumbate building units to construct three-dimensional (3D) frameworks is very important and highly desirable because such materials would possess new physical properties and potential applications. Here, by employing tetrakis(N-imidazolemethylene)methane(TIMM) as a structure-directing agent, the first 3D haloplumbate framework constructed from unprecedented Lindqvist-like highly coordinated [Pb6 Br25 ]13- nanoclusters has been successfully prepared under hydrothermal condition, where all Pb2+ centres in [Pb6 Br25 ]13- nanoclusters adopt seven-/eight-coordinated configurations. The as-obtained material is a wide-gap semiconductor (≈3.1 eV) and can be stable up to 320 °C. More importantly, this material has been demonstrated to show temperature-dependent emission. Our results could provide a new strategy to explore novel metal-halide open-framework materials.

7.
J Am Chem Soc ; 140(33): 10416-10420, 2018 08 22.
Artigo em Inglês | MEDLINE | ID: mdl-30084630

RESUMO

We report a novel type of structurally defined graphene nanoribbons (GNRs) with uniform width of 1.7 nm and average length up to 58 nm. These GNRs are decorated with pending Diels-Alder cycloadducts of anthracenyl units and N- n-hexadecyl maleimide. The resultant bulky side groups on GNRs afford excellent dispersibility with concentrations of up to 5 mg mL-1 in many organic solvents such as tetrahydrofuran (THF), two orders of magnitude higher than the previously reported GNRs. Multiple spectroscopic studies confirm that dilute dispersions in THF (<0.1 mg mL-1) consist mainly of nonaggregated ribbons, exhibiting near-infrared emission with high quantum yield (9.1%) and long lifetime (8.7 ns). This unprecedented dispersibility allows resolving in real-time ultrafast excited-state dynamics of the GNRs, which displays features of small isolated molecules in solution. This study achieves a breakthrough in the dispersion of GNRs, which opens the door for unveiling obstructed GNR-based physical properties and potential applications.

8.
Angew Chem Int Ed Engl ; 57(13): 3366-3371, 2018 03 19.
Artigo em Inglês | MEDLINE | ID: mdl-29397013

RESUMO

Structurally well-defined graphene nanoribbons (GNRs) have attracted great interest because of their unique optical, electronic, and magnetic properties. However, strong π-π interactions within GNRs result in poor liquid-phase dispersibility, which impedes further investigation of these materials in numerous research areas, including supramolecular self-assembly. Structurally defined GNRs were synthesized by a bottom-up strategy, involving grafting of hydrophilic poly(ethylene oxide) (PEO) chains of different lengths (GNR-PEO). PEO grafting of 42-51 % percent produces GNR-PEO materials with excellent dispersibility in water with high GNR concentrations of up to 0.5 mg mL-1 . The "rod-coil" brush-like architecture of GNR-PEO resulted in 1D hierarchical self-assembly behavior in the aqueous phase, leading to the formation of ultralong nanobelts, or spring-like helices, with tunable mean diameters and pitches. In aqueous dispersions the superstructures absorbed in the near-infrared range, which enabled highly efficient conversion of photon energy into thermal energy.

9.
J Am Chem Soc ; 138(32): 10136-9, 2016 08 17.
Artigo em Inglês | MEDLINE | ID: mdl-27463961

RESUMO

Structurally well-defined graphene nanoribbons (GNRs) have attracted great interest as next-generation semiconductor materials. The functionalization of GNRs with polymeric side chains, which can widely broaden GNR-related studies on physiochemical properties and potential applications, has remained unexplored. Here, we demonstrate the bottom-up solution synthesis of defect-free GNRs grafted with flexible poly(ethylene oxide) (PEO) chains. The GNR backbones possess an armchair edge structure with a width of 1.0-1.7 nm and mean lengths of 15-60 nm, enabling near-infrared absorption and a low bandgap of 1.3 eV. Remarkably, the PEO grafting renders the GNRs superb dispersibility in common organic solvents, with a record concentration of ∼1 mg mL(-1) (for GNR backbone) that is much higher than that (<0.01 mg mL(-1)) of reported GNRs. Moreover, the PEO-functionalized GNRs can be readily dispersed in water, accompanying with supramolecular helical nanowire formation. Scanning probe microscopy reveals raft-like self-assembled monolayers of uniform GNRs on graphite substrates. Thin-film-based field-effect transistors (FETs) of the GNRs exhibit a high carrier mobility of ∼0.3 cm(2) V(-1) s(-1), manifesting promising application of the polymer-functionalized GNRs in electronic devices.

10.
J Am Chem Soc ; 137(36): 11602-5, 2015 Sep 16.
Artigo em Inglês | MEDLINE | ID: mdl-26323332

RESUMO

We present a novel type of "rod-coil" graft copolymer containing a polyphenylene backbone linked with poly(ethylene oxide) (PEO) side chains. Such graft copolymers manifest unprecedented temperature-dependent one-dimensional (1D) and two-dimensional (2D) self-assembly in solution. At 20 °C, which is higher than the crystallization temperature (Tc) of the PEO chains, the achiral graft copolymers self-organize into nanoribbons that twist into ∼30 µm ultralong helices with controlled pitch depending on the grafting ratio of the PEO chains. At 10 °C, which is lower than the Tc, quadrangular multilayer sheets of over 10 µm in lateral size are obtained. To our knowledge, this work presents the first example of controlled self-assembly of graft polymers into 1D helix and 2D sheet superstructures.

11.
J Tradit Chin Med ; 34(1): 48-51, 2014 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-25102690

RESUMO

OBJECTIVE: To assess the therapeutic effect of weekend fasting and administration of a modified Lingguizhugan decoction on metabolic syndrome (MetS). METHODS: Twenty-one patients with MetS were recruited from the First Affiliated Hospital of Sun Yat-Sen University. Fasting plasma glucose (FPG), 30-min and 2-h post-prandial blood glucose (PG), fasting serum insulin (FINS), blood pressure (BP), body mass index (BMI), waist circumference (WC), homeostasis model assessment for insulin resistance index (HOMA-IR), and levels of triglyceride (TG), total cholesterol (TC), low-density lipoprotein-cholesterol (LDL-C), and high-density lipoprotein cholesterol (HDL-C) were tested. Patients were allowed to drink only water and a Chinese herbal decoction during weekends. All samples were tested again after 12 weeks of treatment. RESULTS: FPG, 30-min PG, 2-h PG, FINIS, LDL-C, systolic BP, diastolic BP, BMI, WC, and HOMA-IR decreased significantly (P < 0.05) compared with before treatment. Levels of TG, TC, and HDL-C did not change significantly. CONCLUSION: Weekend fasting improved glucose metabolism, lowered BP, reduced LDL-C levels, BMI, and WC. These data suggest that weekend fasting may be an effective therapy for MetS by protection against coronary atherosclerosis.


Assuntos
Medicamentos de Ervas Chinesas/administração & dosagem , Jejum/metabolismo , Síndrome Metabólica/tratamento farmacológico , Adulto , Idoso , Glicemia/metabolismo , HDL-Colesterol/sangue , LDL-Colesterol/sangue , Feminino , Humanos , Masculino , Síndrome Metabólica/metabolismo , Síndrome Metabólica/fisiopatologia , Pessoa de Meia-Idade
12.
Colloids Surf B Biointerfaces ; 115: 368-76, 2014 Mar 01.
Artigo em Inglês | MEDLINE | ID: mdl-24463097

RESUMO

A novel type of reduction-sensitive starch nanoparticles was prepared via the reversed-phase microemulsion method by using crosslinker, N,N-bisacryloylcystamine (BAC) with the disulfide linkages, which was specifically cleaved by dithiothreitol (DTT). Starch nanoparticles had a spherical morphology with a small size of 40 nm in the optimal condition. The influences of process parameters (starch amount, surfactant amount and oil/water (O/W) ratio) on the size of starch nanoparticles were studied by dynamic light scattering (DLS). BAC crosslinked starch nanoparticles were degraded into oligomers with the reducing agent of DTT due to the cleavage of the disulfide linkages. A model drug 5-aminosalicylic acid (5-ASA) could be loaded efficiently into starch nanoparticles and the in vitro drug release behaviors were also studied. The results suggested that the disulfide crosslinked starch nanoparticles exhibited an accelerated drug release behavior in the presence of DTT. In vitro methyl thiazolyl tetrazolium (MTT) assays indicated that BAC crosslinked starch nanoparticles had a good biocompatibility when cocultured with human HeLa cancer cells. Hence, with excellent biocompatibility and biodegradability, and rapid drug release in response to DTT, BAC crosslinked starch nanoparticles showed a great potential as a biomaterial carrier for the application of drug controlled release. In contrast to BAC crosslinked starch nanoparticles, N,N-methylenebisacrylamine (MBA) crosslinked starch nanoparticles were prepared as the control without the disulfide linkages.


Assuntos
Sistemas de Liberação de Medicamentos/métodos , Nanopartículas/química , Amido/química , Morte Celular/efeitos dos fármacos , Sobrevivência Celular/efeitos dos fármacos , Reagentes para Ligações Cruzadas/química , Cistamina/química , Preparações de Ação Retardada , Ditiotreitol/farmacologia , Células HeLa , Humanos , Luz , Mesalamina/farmacologia , Nanopartículas/ultraestrutura , Óleos/química , Oxirredução/efeitos dos fármacos , Tamanho da Partícula , Espalhamento de Radiação , Solubilidade/efeitos dos fármacos , Espectroscopia de Infravermelho com Transformada de Fourier , Amido/síntese química , Tensoativos/química , Água/química
13.
Carbohydr Polym ; 96(2): 426-34, 2013 Jul 25.
Artigo em Inglês | MEDLINE | ID: mdl-23768583

RESUMO

This paper is considered as the first report on the investigation of nattokinase (NK) release from anionic starch nanospheres. The ultra-small and anionic starch nanospheres were prepared by the method of reverse micro-emulsion crosslinking in this work. Starch nanospheres were characterized through Fourier transform infrared (FTIR) spectroscopy, scanning electron microscopy (SEM), transmission electron microscopy (TEM) and dynamic light scattering (DLS). Effects of preparation conditions on particle size were studied. The cytotoxicity, biodegradable and vitro thrombolytic behaviors of nattokinase (NK) loaded anionic starch nanospheres were also studied. The results showed that the anionic starch nanospheres are non-toxic, biocompatible and biodegradable. Moreover, the anionic starch nanospheres can protect NK from fast biodegradation hence prolongs the circulation in vivo and can reduce the risk of acute hemorrhage complication by decreasing the thrombolysis rate.


Assuntos
Citotoxinas/química , Fibrinolíticos/química , Nanosferas/química , Amido/química , Subtilisinas/química , Animais , Ânions/química , Coagulação Sanguínea/efeitos dos fármacos , Sobrevivência Celular/efeitos dos fármacos , Galinhas , Citotoxinas/farmacologia , Fibrinolíticos/farmacologia , Células HeLa , Humanos , Subtilisinas/farmacologia
14.
Int J Biol Macromol ; 58: 231-9, 2013 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-23587995

RESUMO

This research demonstrated the preparation of ultra-small cationic starch nanospheres for the first time. Unlike conventional cationic starch, the cationic starch in here could not form gel. The starch nanoparticles were obtained via reverse micro-emulsion method and were characterized by Fourier transform infrared (FTIR) spectroscopy, Transmission electron microscopy (TEM) and Dynamic light scattering (DLS). The formation mechanism of cationic starch nanospheres was proposed and the effects of preparation conditions on particle size were also investigated. A cationic starch nanosphere with a size of 50 nm can be obtained under the optimal condition. Moreover, the drug release behaviors, cytotoxicity test and degradation analysis were tested and indicated that the particles possess good capacity in delivering the negatively charged molecules, biocompatibility and biodegradability. Thus, the cationic nanoparticles exhibit potential applications in the areas of food and medical sciences.


Assuntos
Portadores de Fármacos/química , Nanosferas/química , Amido/química , Proteína Morfogenética Óssea 4/química , Cátions , Sobrevivência Celular/efeitos dos fármacos , Portadores de Fármacos/toxicidade , Células HeLa , Humanos , Cinética , Nanosferas/toxicidade , Tamanho da Partícula , Soroalbumina Bovina/química , Espectroscopia de Infravermelho com Transformada de Fourier
15.
Int J Biol Macromol ; 51(4): 668-74, 2012 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-22782070

RESUMO

Carboxymethyl potato starch (CMPS) was synthesized with a simple dry and multi-step method as a product of the reaction of native potato starch and monochloroacetic acid in the presence of sodium hydroxide. The influence of the molar ratio of sodium hydroxide to anhydroglucose unit, the volume of 95% (v/v) ethanol, the rotation rate of motor driven stirrer and the reaction time for degree of substitution (DS) were evaluated. The product was characterized by Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM) and X-ray diffractometry (XRD). FTIR spectrometry showed new bonds at 1618 and 1424 cm⁻¹ when native starch underwent carboxymethylation. SEM pictures showed that the smooth surface of native starch particles was mostly ruptured. XRD revealed that starch crystallinity was reduced after carboxymethylation. The viscosity of the mixture paste of carboxymethyl starch and sodium alginate (SA) was measured using a rotational viscometer. In addition, the applied effect of mixed paste in reactive dye printing was examined by assessing the fabric stiffness, color yield and sharp edge to the printed image in comparison with SA. And the results indicated that the mixed paste could partially replace SA as thickener in reactive dye printing. The study also showed that the method was low cost and eco-friendly and the product would have an extensive application in reactive dye printing.


Assuntos
Corantes/química , Impressão/métodos , Solanum tuberosum/química , Amido/análogos & derivados , Química Verde , Compostos Orgânicos , Amido/síntese química , Amido/química , Viscosidade
16.
Int J Biol Macromol ; 50(1): 250-6, 2012 Jan 01.
Artigo em Inglês | MEDLINE | ID: mdl-22100869

RESUMO

This study was carried out to develop a new type of modified starch based on α-amylase and glucoamylase. The structural and chemical characteristics of the porous starch were determined by Fourier-transform infrared (FTIR) spectroscopy, scanning electron microscopy (SEM), X-ray diffraction (XRD) and differential scanning calorimetry (DSC). The potential application of the porous starch as an adsorbent was evaluated using methyl violet as an adsorbed model. The adsorption capacity was optimized by investigating the reaction factors, including the mass ratio of α-amylase to glucoamylase (m(α-amylase)/m(glucoamylase)), the mass ratio of total amount of enzymes to starch (m(enzyme)/m(St)), the ratio of liquid volume to starch mass (V(H2O)/M(St)), pH value of the reaction solution, enzymatic reaction temperature, and enzymatic reaction time. The hydrolysis ratio of each sample was also determined to investigate the effect of different reaction conditions on the hydrolysis degree. The results suggest that the porous starch has a more excellent adsorption capacity than the native starch, and may be expected to have wide potential applications in many fields.


Assuntos
Amido/química , Zea mays/química , Adsorção , Varredura Diferencial de Calorimetria/métodos , Glucana 1,4-alfa-Glucosidase/química , Concentração de Íons de Hidrogênio , Hidrólise , Microscopia Eletrônica de Varredura/métodos , Porosidade , Espectroscopia de Infravermelho com Transformada de Fourier/métodos , Temperatura , Fatores de Tempo , Difração de Raios X , alfa-Amilases/química
17.
J Phys Chem B ; 115(50): 14947-55, 2011 Dec 22.
Artigo em Inglês | MEDLINE | ID: mdl-22082119

RESUMO

A well-defined thermoresponsive poly(ethylene glycol)-block-poly(N-isopropylacrylamide)-block-poly(ε-caprolactone) (PEG(43)-b-PNIPAM(82)-b-PCL(87)) triblock copolymer was synthesized by combination of atom transfer radical polymerization (ATRP), ring-opening polymerization (ROP), and click chemistry. The synthesis included the four steps, and all the structures of the polymers were determined. The thermoresponsive triblock copolymer can disperse in water at room temperature to form core-shell-corona micelles with the hydrophobic PCL block as core, the thermoresponsive PNIPAM block as shell, and the hydrophilic PEG block as corona. At temperatures above the lower critical solution temperature (LCST) of the PNIPAM block, the PNIPAM chains gradually collapse on the PCL core to shrink the size and change the structure of the resultant core-shell-corona micelles with temperature increasing.

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