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1.
Inorg Chem ; 58(21): 14325-14330, 2019 Nov 04.
Artigo em Inglês | MEDLINE | ID: mdl-31622085

RESUMO

The photoluminescence of lanthanide ions inside fullerenes is usually very weak due to the quenching effect of the fullerene cage. In the case of Er@C82, the near-infrared emission from the Er3+ ion is completely quenched by the C82 fullerene cage. It remains challenging to turn on the photoluminescence of Er@C82 and other monometallofullerenes. In this work, we adopt a covalent modification strategy to alter the electronic structure of the fullerene cage for sensitizing the near-infrared emission of Er3+ ions in metallofullerenes Er@C2n (2n = 72, 76, and 82). After covalent modification with trifluoromethyl, phenyl, or dichlorophenyl groups, the erbium metallofullerenes exhibit photoluminescence at 1.5 µm, which is the characteristic emission of the Er3+ ion. Particularly, the otherwise nonfluorescent metallofullerene Er@C82 is transformed into fluorescent derivatives by using this strategy. The photoluminescence from the Er3+ ion is ascribed to energy transfer from the fullerene cage to the Er3+ ion. According to theoretical calculations, the sensitization of the Er3+ ion by the fullerene cage is associated with the large HOMO-LUMO gap and the closed-shell electronic structure of the metallofullerene derivatives. This work provides useful guidance for the design and synthesis of new fluorescent metallofullerenes.

3.
J Am Chem Soc ; 140(3): 1123-1130, 2018 01 24.
Artigo em Inglês | MEDLINE | ID: mdl-29272584

RESUMO

An anisotropic high-spin qubit with long coherence time could scale the quantum system up. It has been proposed that Grover's algorithm can be implemented in such systems. Dimetallic aza[80]fullerenes M2@C79N (M = Y or Gd) possess an unpaired electron located between two metal ions, offering an opportunity to manipulate spin(s) protected in the cage for quantum information processing. Herein, we report the crystallographic determination of Gd2@C79N for the first time. This molecular magnet with a collective high-spin ground state (S = 15/2) generated by strong magnetic coupling (JGd-Rad = 350 ± 20 cm-1) has been unambiguously validated by magnetic susceptibility experiments. Gd2@C79N has quantum coherence and diverse Rabi cycles, allowing arbitrary superposition state manipulation between each adjacent level. The phase memory time reaches 5 µs at 5 K by dynamic decoupling. This molecule fulfills the requirements of Grover's searching algorithm proposed by Leuenberger and Loss.

4.
J Org Chem ; 82(17): 9253-9257, 2017 09 01.
Artigo em Inglês | MEDLINE | ID: mdl-28748692

RESUMO

The C70 δ-adducts with closed [5,6]-ring fusion are an important type of compound in classifying bond delocalization in the equatorial belt of C70. However, the formation of such compounds is severely restricted due to the low reactivity of the carbon atoms in the flat equatorial region. Such a restriction is lifted when reduced anionic C70 species are used, where the inert equatorial carbon atoms are activated.

5.
Int J Nanomedicine ; 12: 4177-4194, 2017.
Artigo em Inglês | MEDLINE | ID: mdl-28615944

RESUMO

Single-wall carbon nanohorns (SWCNHs), which have multitudes of horn interstices, an extensive surface area, and a spherical aggregate structure, offer many advantages over other carbon nanomaterials being used as a drug nanovector. The previous studies on the interaction between SWCNHs and cells have mostly emphasized on cellular uptake and intracellular trafficking, but seldom on epithelial cells. Polar epithelium as a typical biological barrier constitutes the prime obstacle for the transport of therapeutic agents to target site. This work tried to explore the permeability of SWCNHs through polar epithelium and their abilities to modulate transcellular transport, and evaluate the potential of SWCNHs in drug delivery. Madin-Darby canine kidney (MDCK) cell monolayer was used as a polar epithelial cell model, and as-grown SWCNHs, together with oxidized and fluorescein isothiocyanate-conjugated bovine serum albumin-labeled forms, were constructed and comprehensively investigated in vitro and in vivo. Various methods such as transmission electron microscopy and confocal imaging were used to visualize their intracellular uptake and localization, as well as to investigate the potential transcytotic process. The related mechanism was explored by specific inhibitors. Additionally, fast multispectral optoacoustic tomography imaging was used for monitoring the distribution and transport process of SWCNHs in vivo after oral administration in nude mice, as an evidence for their interaction with the intestinal epithelium. The results showed that SWCNHs had a strong bioadhesion property, and parts of them could be uptaken and transcytosed across the MDCK monolayer. Multiple mechanisms were involved in the uptake and transcytosis of SWCNHs with varying degrees. After oral administration, oxidized SWCNHs were distributed in the gastrointestinal tract and retained in the intestine for up to 36 h probably due to their surface adhesion and endocytosis into the intestinal epithelium. Overall, this comprehensive investigation demonstrated that SWCNHs can serve as a promising nanovector that can cross the barrier of polar epithelial cells and deliver drugs effectively.


Assuntos
Carbono/química , Epitélio/efeitos dos fármacos , Intestinos/citologia , Nanoestruturas/química , Administração Oral , Animais , Cães , Sistemas de Liberação de Medicamentos/métodos , Endocitose , Fluoresceína-5-Isotiocianato/análogos & derivados , Fluoresceína-5-Isotiocianato/química , Células Madin Darby de Rim Canino , Camundongos Nus , Microscopia Eletrônica de Transmissão , Nanoestruturas/administração & dosagem , Técnicas Fotoacústicas , Soroalbumina Bovina/química
6.
Chem Commun (Camb) ; 52(31): 5391-3, 2016 Apr 07.
Artigo em Inglês | MEDLINE | ID: mdl-27006980

RESUMO

Boron-, phosphorus-, nitrogen-doped and co-doped single-wall carbon nanohorns were produced using an arc-vaporization method. These as-prepared doped materials consist of uniform isolated nanohorns and exhibit greatly enhanced catalytic capabilities in the reduction reaction of nitrobenzene and a volcano-shape trend between their activities with a B dopant content is found. Moreover, the B-C3 and P-C3 species in doped nanohorns might act as the acidic and basic sites to promote this reaction.

7.
Soft Matter ; 11(23): 4621-9, 2015 Jun 21.
Artigo em Inglês | MEDLINE | ID: mdl-25959650

RESUMO

Recent research has indicated that polydopamine and synthetic eumelanins are optoelectronic biomaterials in which one-dimensional aggregates composed of ordered-stacking oligomers have been proposed as unique organic semiconductors. However, improving the ordered-stacking of oligomers in polydopamine nanostructures is a big challenge. Herein, we first demonstrate how folic acid molecules influence the morphology and nanostructure of polydopamine via tuning the π-π interactions of oligomers. MALDI-TOF mass spectrometry reveals that porphyrin-like tetramers are characteristic of folic acid-polydopamine (FA-PDA) nanofibers. X-ray diffraction combined with simulation studies indicate that these oligomers favour aggregation into graphite-like ordered nanostructures via strong π-π interactions. High-resolution TEM characterization of carbonized FA-PDA hybrids show that in FA-PDA nanofibers the size of the graphite-like domains is over 100 nm. The addition of folic acid in polydopamine enhances the ordered stacking of oligomers in its nanostructure. Our study steps forward to discover the mystery of the structure-property relationship of FA-PDA hybrids. It paves a way to optimize the properties of PDA through the design and selection of oligomer structures.


Assuntos
Ácido Fólico/química , Indóis/química , Nanofibras/química , Polímeros/química , Nanofibras/ultraestrutura
8.
Inorg Chem ; 54(9): 4243-8, 2015 May 04.
Artigo em Inglês | MEDLINE | ID: mdl-25782103

RESUMO

Although a non-IPR fullerene cage is common for endohedral cluster fullerenes, it is very rare for conventional endofullerenes M@C2n, probably because of the minimum geometry fit effect of the endohedral single metal ion. In this work, we report on a new non-IPR endofullerene Sm@C2v(19138)-C76, including its structural and electrochemical features. A combined study of single-crystal X-ray diffraction and DFT calculations not only elucidates the non-IPR cage structure of C2v(19138)-C76 but also suggests that the endohedral Sm(2+) ion prefers to reside along the C2 cage axis and close to the fused pentagon unit in the cage framework, indicative of a significant metal-cage interaction, which alone can stabilize the non-IPR cage. Furthermore, electrochemical studies reveal the fully reversible redox behaviors and small electrochemical gap of Sm@C2v(19138)-C76, which are comparable to those of IPR species Sm@D3h-C74.


Assuntos
Fulerenos/química , Níquel/química , Cátions Bivalentes , Cristalografia por Raios X , Técnicas Eletroquímicas , Isomerismo , Estrutura Molecular , Oxirredução , Teoria Quântica
9.
Inorg Chem ; 54(5): 2103-8, 2015 Mar 02.
Artigo em Inglês | MEDLINE | ID: mdl-25679437

RESUMO

Two Sm@C82 isomers have been well characterized for the first time by means of (13)C NMR spectroscopy, and their structures were unambiguously determined as Sm@C2v(9)-C82 and Sm@C3v(7)-C82, respectively. A combined study of single crystal X-ray diffraction and theoretical calculations suggest that in Sm@C2v(9)-C82 the preferred Sm(2+) ion position shall be located in a region slightly off the C2 axis of C2v(9)-C82. Moreover, the electrochemical surveys on these Sm@C82 isomers reveal that their redox activities are mainly determined by the properties of their carbon cages.

10.
ACS Appl Mater Interfaces ; 6(20): 18008-17, 2014 Oct 22.
Artigo em Inglês | MEDLINE | ID: mdl-25248075

RESUMO

The biomedical applications of carbon nanomaterials, especially integrating noninvasive photothermal therapy (PTT) and photodynamic therapy (PDT), into a single system have enormous potential in cancer therapy. Herein, we present a novel and facile one-step method for the preparation of water-soluble single-walled carbon nanohorns (SWNHs) and metal phthalocyanines (MPc) hybrid for PTT and PDT. The hydrophilic MPc, tetrasulfonic acid tetrasodium salt copper phthalocyanine (TSCuPc), is coated on the surface of SWNHs via noncovalent π-π interaction using the sonication method. In this PTT/PDT nanosystem, SWNHs acts as a photosensitizer carrier and PTT agent, while TSCuPc acts as a hydrophilic and PDT agent. The EPR results demonstrated that the generated reactive oxygen species (ROS) not only from the photoinduced electron transfer process from TSCuPc to SWNHs but also from SWNHs without exciting TSCuPc to its excited state. The test of photothermal conversion proved that not only do SWNHs contribute to the photothermal therapy (PTT) effect, TSCuPc probably also contributes to that when it coats on the surface of SWNHs upon exposure to a 650-nm laser. More importantly, the results of in vitro cell viability revealed a significantly enhanced anticancer efficacy of combined noninvasive PTT/PDT, indicating that the SWNHs-TSCuPc nanohybrid is a hopeful candidate material for developing an efficient and biocompatible nanoplatform for biomedical application.


Assuntos
Hipertermia Induzida , Indóis/química , Nanopartículas/uso terapêutico , Nanotecnologia/métodos , Fotoquimioterapia , Fototerapia , Água/química , Carbono/química , Morte Celular/efeitos dos fármacos , Espectroscopia de Ressonância de Spin Eletrônica , Células HeLa , Humanos , Microscopia Confocal , Nanopartículas/toxicidade , Nanopartículas/ultraestrutura , Fotodegradação , Espectroscopia Fotoeletrônica , Solubilidade , Análise Espectral Raman , Termogravimetria , Fatores de Tempo
11.
Langmuir ; 30(19): 5497-505, 2014 May 20.
Artigo em Inglês | MEDLINE | ID: mdl-24773501

RESUMO

Polydopamine is not only a multifunctional biopolymer with promising optoelectronic properties but it is also a versatile coating platform for different surfaces. The structure and formation of polydopamine is an active area of research. Some studies have supposed that polydopamine is composed of covalently bonded dihydroxyindole, indoledione, and dopamine units, but others proposed that noncovalent self-assembly contributes to polydopamine formation as well. However, it is difficult to directly find the details of supramolecular structure of polydopamine via self-assembly. In this study, we first report the graphite-like nanostructure observed in the carbonized polydopamine nanoparticles in nitrogen (or argon) environment at 800 °C. Raman characterization, which presents the typical D band and G band, confirmed the existence of graphite-like nanostructures. Our observation provides clear evidence for a layered-stacking supramolecular structure of polydopamine. Particularly, the size of graphite-like domains is similar to that of disk-shaped aggregates hypothesized in previous study about the polymerization of 5,6-dihydroxyindole [ Biomacromolecules 2012 , 13 , 2379 ]. Analysis of the hierarchical structure of polydopamine helps us understand its formation.


Assuntos
Indóis/química , Nanopartículas/química , Nanoestruturas/química , Polímeros/química
12.
Nanoscale ; 5(21): 10409-13, 2013 Nov 07.
Artigo em Inglês | MEDLINE | ID: mdl-24056947

RESUMO

A metallofullerene Sm@D3h-C74 that contains a divalent rare-earth metal has been studied structurally and electrochemically. The crystallographic analysis revealed that the endohedral Sm atom is more or less motional rather than being localized at a site where the pyracylene motif is nearby. This suggests a weaker metal-pyracylene interaction in Sm@D3h-C74 relative to that in M(II)@C74 (M = Group II metal), thus confirming the importance of the metal variety. The electrochemical studies showed a major difference between the redox properties of Sm@D3h-C74 and other Sm-fullerenes and indicated a small band gap for the title compound.

13.
J Am Chem Soc ; 135(11): 4187-90, 2013 Mar 20.
Artigo em Inglês | MEDLINE | ID: mdl-23465292

RESUMO

We report the synthesis, isolation, and characterizations of the novel trimetallofullerene Sm3@I(h)-C80. Importantly, the experimental X-ray structure of Sm3@I(h)-C80 verified for the first time that three metal atoms can be stabilized in a fullerene cage without a nonmetal mediator. Furthermore, computational studies demonstrated the electronic features of Sm3@I(h)-C80, which are similar to that of theoretically studied Y3@I(h)-C80. Electrochemical studies of Sm3@I(h)-C80 showed a major difference from those of the well-studied isoelectronic species Sc3N@I(h)-C80 and La2@I(h)-C80.

14.
Nanoscale Res Lett ; 8(1): 100, 2013 Feb 22.
Artigo em Inglês | MEDLINE | ID: mdl-23432919

RESUMO

Single-wall carbon nanohorns (SWNHs) have been demonstrated to accumulate in cytotoxic levels within organs of various animal models and cell types, which emerge as a wide range of promising biomedical imaging. Septic encephalopathy (SE) is an early sign of sepsis and associated with an increased rate of morbidity and mortality. Microglia activation plays an important role in neuroinflammation, which contributes to neuronal damage. Inhibition of microglia activation may have therapeutic benefits, which can alleviate the progression of neurodegeneration. Therefore, we investigated the functional changes of mice microglia cell lines pre-treated with or without lipopolysaccharide (LPS) induced by SWNHs. To address this question, the research about direct role of SWNHs on the growth, proliferation, and apoptosis of microglia cell lines in mice (N9 and BV2) pre-treated with or without LPS had been performed. Our results indicate that the particle diameter of SWNHs in water is between 342 to 712 nm. The images in scanning electron microscope showed that SWNHs on polystyrene surface are individual particles. LPS induced activation of mice microglia, promoted its growth and proliferation, and inhibited its apoptosis. SWNHs inhibited proliferation, delayed mitotic entry, and promoted apoptosis of mice microglia cells. The effects followed gradually increasing cultured time and concentrations of SWNHs, especially in cells pre-treated with LPS. SWNHs induced a significantly increase in G1 phase and inhibition of S phase of mice microglia cells in a dose-manner dependent of SWNHs, especially in cells pre-treated with LPS. The transmission electron microscope images showed that individual spherical SWNH particles smaller than 100 nm in diameters were localized inside lysosomes of mice microglia cells. SWNHs inhibited mitotic entry, growth and proliferation of mice microglia cells, and promoted its apoptosis, especially in cells pre-treated with LPS. SWNHs inhibited expression of Sirt3 and energy metabolism related with Sirt3 in mice microglia cells in a dose-dependent manner, especially in cells pre-treated with LPS. The role of SWNHs on mice microglia was implicating Sirt3 and energy metabolism associated with it.

16.
J Nanosci Nanotechnol ; 12(9): 7376-81, 2012 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-23035479

RESUMO

Uniform and well dispersed platinum nanoparticles were successfully deposited on single-walled carbon nanohorns with the assistance of 4,4-dipydine and ion liquids, respectively. In particular, the size of platinum nanoparticles could be controlled in a very narrow range (2.2 to 2.5 nm) when ion liquids were applied. The crystalline nature of these platinum nanoparticles was confirmed by high resolution transmission electron microscopy observation and X-ray power diffraction analysis, and two species of platinum Pt(0) and Pt(II) were detected by X-ray photoelectron spectroscopy. Electrochemical studies revealed that thus obtained nanocomposites had much better electrocatalytic activity for the methanol oxidation than those prepared with carbon nanotubes as supporter.

17.
Chemistry ; 18(45): 14246-9, 2012 Nov 05.
Artigo em Inglês | MEDLINE | ID: mdl-23033122

RESUMO

Access to a chiral C(82)  cage: Encaging a divalent samarium atom has provided access to an unexplored chiral cage of C(2)(5)-C(82) that has never been reported for trivalent M@C(82) or empty fullerenes. Inside this cage, a wandering Sm atom has been identified using crystallographic methods. In addition, electrochemical studies of Sm@C(2)(5)-C(82) have been performed to explore its oxidation properties (see figure).


Assuntos
Fulerenos/química , Samário/química , Carbono/química , Cristalografia por Raios X , Técnicas Eletroquímicas , Espectroscopia de Ressonância Magnética , Conformação Molecular , Oxirredução , Estereoisomerismo
18.
Nanoscale ; 4(21): 6876-9, 2012 Nov 07.
Artigo em Inglês | MEDLINE | ID: mdl-23023345

RESUMO

A new metallofullerene Sm@C(2v)(3)-C(80) was synthesized and characterized. X-Ray analysis showed that the endohedral Sm atom undergoes a hopping motion between several off-center sites, even at low temperature. In addition, a comparative electrochemical study between Sm@C(2v)(3)-C(80) and Yb@C(2v)(3)-C(80) revealed their different redox potentials, suggesting a metal-induced effect on their redox profiles.

19.
Ultramicroscopy ; 119: 72-7, 2012 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-22244495

RESUMO

We demonstrate the potential of electrons for single molecule diffraction and imaging using C60 molecules confined inside single-walled carbon nanotubes (C60s@SWCNT or peapod) as a model system. A 25 nm diameter electron beam from a field emission gun source is used to record diffraction patterns from individual peapods using imaging plates. The electron beam illuminates about 25 C60 molecules. Experimentally, we found that the molecules diffract inside ∼15% of the host nanotubes. With the help of simulations, we explore the limits of electron molecular diffraction and its sensitivity to the molecular configurations. We show that the combination of electron diffraction and electron direct imaging provides the best approach to single molecule imaging.

20.
J Nanosci Nanotechnol ; 11(5): 4034-8, 2011 May.
Artigo em Inglês | MEDLINE | ID: mdl-21780402

RESUMO

Electrochemical properties of a novel nanohybrid material, ferrocene-filled double-walled carbon nanotubes (Fc@DWNTs), have been successfully investigated for the first time by preparing different kinds of Fc@DWNTs modified glassy carbon electrodes. One pair of surface-confined redox waves corresponding to the couple of Fc/Fc+ is obtained, indicating Fc encapsulated in DWNTs retains electrochemical activity. Significantly differing from those of ferrocene-filled single-walled carbon nanotubes (Fc@SWNTs), Fc@DWNTs shows a specific electrochemical behavior, typically exhibiting thin-layer electrochemical characteristics at low scan rates, whereas diffusion-confined characteristics at high scan rates. The results indicate that the novel nanohybrid material possessing excellent electrochemical properties may have possible applications in constructing specific chemical and biological sensors.

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