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1.
Artigo em Inglês | MEDLINE | ID: mdl-31780309

RESUMO

Hydrogen sulfide shows great importance in various physiological and biochemical processes. The development of fluorescence probes for facile and efficient detection of H2S has attracted increasing attention of researchers. Herein, we synthesized two fluorescence probes based on simple naphthalene structure for detection of H2S. Upon reaction with H2S, the probe DN-DM exhibited a red fluorescence emission with large Stokes shift. The probe showed high sensitivity, pH insensitivity and good selectivity for H2S over other analytes including common biothiols. The detection mechanism was based on the thiolysis of the dinitrophenyl ether moiety, which was confirmed by 1H NMR spectral analysis. The DFT calculation was also performed for a deeper understanding of the photophysical properties. In addition, these probes showed good cell-membrane permeability and could be utilized for detection of H2S in living cells.

2.
J Biomed Nanotechnol ; 15(9): 1867-1880, 2019 Sep 01.
Artigo em Inglês | MEDLINE | ID: mdl-31387675

RESUMO

The present study aims to evaluate the effect of the ethyl acetate extract of Cichorium (EAEC) as a novel photosensitizer in photodynamic therapy (PDT) of colorectal carcinoma (CRC) HCT116 and SW620 cells. The absorption and fluorescence spectra of EAEC were measured using a UV-vis spectrophotometer and fluorescence spectrophotometer, respectively. EAEC-induced reactive oxygen species (ROS) production in HCT116 and SW620 cells was detected using 2',7'-dichlorodihydrofluorescein diacetate (DCFH-DA) and glutathione/glutathione disulfide (GSH/GSSG). The photo- and dark toxicities of EAEC were estimated using the Cell Counting Kit-8 (CCK-8) assay. Cellular uptake and localization of EAEC were detected by confocal laser fluorescence microscopy. Annexin V-FITC/PI staining, Western blotting and immunofluorescence staining were used to assess apoptosis and autophagy. The antitumor activity of EAEC was confirmed in a xenograft model. Finally, effects on the PERK pathway were verified using qRT-PCR and Western blotting. EAEC displayed absorption and fluorescence emission peaks at 660 nm and 678 nm, respectively. EAEC induced ROS production in CRC cells. Assessment of dark toxicity showed that treatment with EAEC alone induced little cytotoxicity in CRC or normal cells but that EAEC-PDT induced significant photocytotoxicity in CRC cells in a time- and dose-dependent manner. After cellular uptake, EAEC was located in the mitochondria. Treatment with EAEC-PDT reduced xenograft tumor size. Further evaluation suggested that activation of the PERK pathway mediates these effects, as the apoptotic rate and autophagy flux increased markedly after EAEC-PDT. EAEC, a natural photosensitizer extracted from Cichorium, displays potential utility in PDT of CRC by targeting the PERK pathway.


Assuntos
Autofagia , Neoplasias Colorretais , Fotoquimioterapia , Acetatos , Apoptose , Linhagem Celular , Linhagem Celular Tumoral , Estresse do Retículo Endoplasmático , Humanos , Fármacos Fotossensibilizantes , Proteínas Quinases , Espécies Reativas de Oxigênio
3.
Dig Liver Dis ; 51(10): 1446-1455, 2019 10.
Artigo em Inglês | MEDLINE | ID: mdl-31147216

RESUMO

BACKGROUND: Emerging data suggest the crucial regulatory roles of circular RNAs (circRNAs) in hepatocellular carcinoma (HCC). However, the pathophysiology role of circZFR in HCC remains largely unknown. AIMS: This study aims to disclose the functions of circZFR in HCC progression and its potential molecular mechanism. METHODS: circZFR and miR-511 were identified by qRT-PCR. Colony formation assay, wound-healing assay, transwell assay, and flow cytometry assay were performed to determine the cell proliferation, migration, invasion and apoptosis. Western blotting and immunohistochemistry (IHC) were utilized to evaluate the expression level of AKT1, GSK3ß, ß-catenin and cascades of proliferation-related proteins both in vitro and in vivo. Dual luciferase reporter assay was conducted to evaluate the interactions among circZFR, miR-511 and AKT1. RESULTS: The expression of circZFR was enhanced and the expression of miR-511 was down-regulated in HCC tissues and cells. Functionally, circZFR silencing or miR-511 overexpression suppressed cell proliferation, migration and invasion, and induced apoptosis of HCC cells. Mechanistically, circZFR acted as a miR-511 sponge to up-regulate its target gene AKT1, which activated cascades of proliferation-related proteins (c-Myc, cyclin D1, Survivin and Bcl-2). Furthermore, depletion of circZFR inhibited tumorigenesis and decreased the expression level of AKT1 in xenograft models. CONCLUSION: circZFR promotes HCC progression by directly down-regulating miR-511 to activate AKT1 signaling, suggesting that circZFR is a potential target in HCC treatment. Targeting circZFR may provide therapeutic benefits for HCC.

4.
Inorg Chem ; 58(12): 7947-7957, 2019 Jun 17.
Artigo em Inglês | MEDLINE | ID: mdl-31185555

RESUMO

The mixed hexa-transition metal (hexa-TM) sandwiched arsenotungstate derivative, [CuI3(pz)2(phen)3]2[CuI(phen)2][{Na(H2O)2}{(VIV5CuIIO6)(AsIIIW9O33)2}]·6H2O (1) (pz = pyrazine; phen = 1,10-phenanthroline), has been hydrothermally synthesized and structurally characterized. In compound 1, two {AsW9O33} clusters are connected by mixed hexa-TM ring unit {VVI5CuIIO6} to form a sandwich-type dimer, which are further bonded in "ABAB" mode by the {Na(H2O)2} linker resulting in pure inorganic chains. The unique "L-shaped" trinuclear complex {Cu3(phen)3(pz)2} is supported together via staggered π-π interactions to generate extending waveform two-dimensional supramolecular layers, which are further aggregated with their adjacent analogues by complexes {Cu(phen)2} via H-bonding interaction to yield an unprecedented three-dimensional (3D) metal-organic networks with one-dimensional (1D) cavities. The pure inorganic 1D sandwich chains are implanted in the cavities as guest units via supramolecular interactions to form a POMOF 3D framework. Compound 1, as the electrode of the supercapacitor, exhibits higher specific capacitances (825 F g-1 at a current density of 2.4 A g-1), better rate capability, more durable cyclic stability (91.4% of cycle efficiency after 3000 cycles), and improved conductivity and electroactivity compared to those of parent polyoxometalate (POM) Na9[AsW9O33]·19H2O (2) and 6-Cu-substituted POM [Cu6(imi)6{AsIIIW9O30Cl3}2]·6H2O (3), which may be attributed to the introduction of V4+, the unique host-guest structure, and the rich π electron system. In addition, compound 1 exhibits dual-function electrocatalytic behavior in reducing inorganic salt IO3- and oxidizing the organic molecule dopamine.

5.
Spectrochim Acta A Mol Biomol Spectrosc ; 218: 206-212, 2019 Jul 05.
Artigo em Inglês | MEDLINE | ID: mdl-30995578

RESUMO

Hydrogen sulfide (H2S) is a kind of gaseous signal molecule in many physiological processes. In order to detect H2S, a novel "turn on" fluorescent probe 6,12-dihydroxyperylene-1,7-dione (DPD) was designed and synthesized. The probe DPD is fluorescence silence, while the addition of H2S induces an obvious green fluorescence with an obvious color change from dark blue to yellow-green. The probe shows excellent selectivity, fast response (2.5min) and linear curve (0-90µM) in wide effective pH range (4-10). Competition experiments are also revealed in corresponding studies and the detection limit is 3.6µM. The response mechanism is proved to be the reduction of the probe by H2S, which is confirmed by 1H NMR. Furthermore, through the fluorescence turn-on signal toward H2S in Hela cells, probe DPD was successfully applied to monitor H2S in living Hela cells.


Assuntos
Corantes Fluorescentes/química , Sulfeto de Hidrogênio/análise , Perileno/análogos & derivados , Quinonas/química , Fluorescência , Corantes Fluorescentes/síntese química , Células HeLa , Humanos , Limite de Detecção , Microscopia Confocal , Imagem Óptica , Perileno/síntese química , Perileno/química , Quinonas/síntese química , Espectrometria de Fluorescência
6.
Chem Asian J ; 14(9): 1462-1466, 2019 May 02.
Artigo em Inglês | MEDLINE | ID: mdl-30883030

RESUMO

A general and efficient synthetic methodology for the preparation of enantio- and diastereopure [6]-, and [7]helicenes is developed. Commercially available chiral binaphthanols are utilized to generate the arylene-vinylene precursors, which undergo helical folding via photocyclization to give enantio- and diastereopure [6]-, and [7]helicenes. These optically pure helicenes could be easily obtained via silica gel column chromatography without the use of expensive HPLC or chiral resolution reagents. The configurations and structures of these helicenes are confirmed by CD spectra and X-ray crystallographic analysis. This work provides a new method for preparation of enantiopure helicenes.

7.
Spectrochim Acta A Mol Biomol Spectrosc ; 214: 487-495, 2019 May 05.
Artigo em Inglês | MEDLINE | ID: mdl-30818149

RESUMO

In this work, we have designed and synthesized a dinitrobenzene-sulfonate tetrahydro[5]helicene (H-DNP) as an effective fluorescent probe for detection of hydrogen sulfide (H2S). Upon the addition of H2S, a significant fluorescence enhancement (75-fold) at 495 nm can be observed with a distinct color change from colorless to yellow. Additionally, H-DNP shows low background spectroscopic signal, large Stokes Shift up to ~140 nm, good sensitivity, rapid response time less than 2 min, low detection limit (48 nM) and high selectivity toward common bio-thiols (Cysteine, Homocysteine and Glutathione). Compared with the previous dinitrophenoxy tetrahydro[5]helicene, this probe has shorter response time and lower detection limit. Most importantly, this probe H-DNP has low toxicity to cells and excellent cell permeability, which can be applied to visualize H2S in living cells.


Assuntos
Corantes Fluorescentes , Sulfeto de Hidrogênio/metabolismo , Compostos Policíclicos , Corantes Fluorescentes/síntese química , Corantes Fluorescentes/química , Corantes Fluorescentes/farmacologia , Células HeLa , Humanos , Limite de Detecção , Microscopia de Fluorescência , Compostos Policíclicos/síntese química , Compostos Policíclicos/química , Compostos Policíclicos/farmacologia
8.
Talanta ; 196: 243-248, 2019 May 01.
Artigo em Inglês | MEDLINE | ID: mdl-30683359

RESUMO

In this study, a new coumarin-based fluorescent and chromogenic dual channel probe (DC) was used for the selective detection of homocysteine (Hcy) over other amino acids, especially for cysteine (Cys) and glutathione (GSH). When Hcy is present in the solution, the remarkable fluorescence enhancement and obvious blue shift in UV-vis spectra can be observed. In addition, the color change from purple to yellow can be observed clearly by unaided eyes. This probe DC has fast response time, excellent sensitivity and selectivity to Hcy. A linear relationship exists between the ratio of emissions at 486 and 625 nm, and Hcy can be detected in a wide concentration range (0-200 µM). The signal-to-background ratio of fluorescence at 486 nm can reach 8.4, and the detection limit is calculated to be 3.5 µM. The response mechanism is proved to be the Michael addition reaction by Hcy. Preliminary results on cell imaging enable the practical application of Hcy tracing in living cells.

9.
Scand J Gastroenterol ; 53(12): 1562-1568, 2018 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-30572742

RESUMO

BACKGROUND AND AIMS: The impact of portal hypertension (PH) on postoperative short-term outcomes and long-term survival in hepatocellular carcinoma (HCC) patients has lately been discussed controversially. This study aimed to explore the influence of PH on postoperative outcomes in HCC patients undergoing surgical resection. METHODS: Patients undergoing hepatectomy for HCC from 2010 to 2014 were enrolled. The impact of PH on postoperative complications, posthepatectomy liver failure (PHLF) and overall survival (OS) was evaluated. RESULTS: A total of 355 HCC patients were enrolled; 129 (36.3%) experienced postoperative complications and 21 (5.9%) developed PHLF. PH was identified as an independent predictor of PHLF. Patients with PH experienced a higher incidence of complications and PHLF than patients without PH. On the Cox proportional hazards regression model, PH was verified as a risk factor of OS for BCLC stage 0/A and B patients. Patients without PH had significantly better long-term survival compared to patients with PH both in the total cohort and in cirrhosis subgroup. CONCLUSION: Liver resection in HCC patients with PH showed a significantly increased postoperative complications and PHLF, and revealed a decreasing long-term survival than non-PH patients. Besides, tumor burden also played an important role in determining the OS. However, due to the improvement in surgical technique and perioperative management, surgery was feasible in carefully selected HCC patients with PH.


Assuntos
Carcinoma Hepatocelular/cirurgia , Hipertensão Portal/complicações , Falência Hepática/epidemiologia , Neoplasias Hepáticas/cirurgia , Complicações Pós-Operatórias/epidemiologia , Adulto , Carcinoma Hepatocelular/mortalidade , China/epidemiologia , Feminino , Hepatectomia , Mortalidade Hospitalar , Humanos , Incidência , Cirrose Hepática/complicações , Neoplasias Hepáticas/mortalidade , Masculino , Pessoa de Meia-Idade , Curva ROC , Estudos Retrospectivos , Fatores de Risco , Análise de Sobrevida
10.
Spectrochim Acta A Mol Biomol Spectrosc ; 204: 295-300, 2018 Nov 05.
Artigo em Inglês | MEDLINE | ID: mdl-29945112

RESUMO

Endogenous hydrogen sulfide plays an important role in various physiological and pathological processes and the convenient and selective recognition of hydrogen sulfide has become a research hotspot. We designed and synthesized a tetrahydro[5]helicene and 2,4-dinitrobenzene conjugate (HD-DNP) as an effective fluorescent probe for selective detection of H2S. The selective deprotection of 2,4-dinitrophenyl ether group of HD-DNP by H2S led to a dramatic fluorescent enhancement (101-fold) at 500 nm and colorimetric change in DMSO-PBS solution. HD-DNP displays many advantages including low background without any self-fluorescence, as well as high selectivity towards common bio-thiols such as Cysteine, Homocysteine and Glutathione. The detection limit of this probe for H2S was found to be about 2.4 µM with a wide linear range (10-70 µM). The response mechanism of the probe with HS- is confirmed to be thiolysis of the dinitrophenyl ether induced by HS- through 1H NMR comparison investigations.


Assuntos
Corantes Fluorescentes/química , Sulfeto de Hidrogênio/análise , Compostos Policíclicos/química , Dinitrobenzenos/química , Sulfeto de Hidrogênio/química , Limite de Detecção , Modelos Lineares
11.
Anal Bioanal Chem ; 409(23): 5547-5554, 2017 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-28717898

RESUMO

The thiophene-modified rhodamine 6G (GYJ) has been synthesized as a novel chemosensor. The sensor has sufficiently high selectivity and sensitivity for the detection of Fe3+ and Al3+ ions (M3+) by fluorescence and ultraviolet spectroscopy with a strong ability for anti-interference performance. The binding ratio of M3+-GYJ complex was determined to be 2:1 according to the Job's plot. The binding constants for Fe3+ and Al3+ were calculated to be 3.91 × 108 and 5.26 × 108 M-2, respectively. All these unique features made it particularly favorable for cellular imaging applications. The obvious fluorescence microscopy experiments demonstrated that the probes could contribute to the detection of Fe3+ and Al3+ in related cells and biological organs with satisfying resolution. Graphical abstract GYJ has high selectivity and sensitivity for the detection of Fe(III) and Al(III) with the binding ratio of 2:1.


Assuntos
Alumínio/análise , Compostos Férricos/análise , Corantes Fluorescentes/química , Rodaminas/química , Tiofenos/química , Limite de Detecção , Espectrometria de Fluorescência , Espectrofotometria Ultravioleta
12.
J Fluoresc ; 27(3): 1095-1099, 2017 May.
Artigo em Inglês | MEDLINE | ID: mdl-28233249

RESUMO

An easily available novel fluorescent probe based on rhodamine 6G-thiourea conjugate (RGTU) has been synthesized. Upon mixed with Hg2+ in CH3CN-H2O (1:9, v/v), the dramatic enhancement of fluorescence intensity as well as the color change of the solution were observed. The presence of common coexisting alkali, alkaline earth, and transition metal ions showed small or no interference with the detection of Hg2+. The Job's plot and 1H NMR spectra indicated that Hg2+ induced spirolactam open to form 1:1 complex between RGTU and Hg2+.

13.
J Fluoresc ; 27(2): 629-633, 2017 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-27900512

RESUMO

A coumarin-appended rhodamine derivative was prepared by reacting rhodamine hydrazide and coumarin-3-carboxylic acid, which fluorescence sensing behavior toward Zn2+ against other metal ions was investigated in CH3CN. Significantly, the rodamine-coumarin derivative exhibited highly selective and sensitive recognition toward Zn2+ with a limit of detection (LOD) down to 10-9 M. Upon addition of Zn2+, remarkable fluorescent intensities enhanced and also clear color changed from colorless to pink. The Job's plot indicated the formation of 1:1 complex between the rhodamine-coumarin derivative and Zn2+. The presence of common coexisting alkali, alkaline earth, and transition metal ions showed small or no interference with the detection of Zn2+. The conjugate dye could be used for "naked-eye" detection of Zn2+.

15.
Cell Mol Immunol ; 12(5): 553-7, 2015 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-25640656

RESUMO

Regulatory T (Treg) cells are necessary for immune system homeostasis and the prevention of autoimmune diseases. Foxp3 is specifically expressed in Treg cells and plays a key role in their differentiation and function. Foxp3(+) Treg cells are consisted of naturally occurring, thymus-derived Treg (nTreg) and peripheral-induced Treg (iTreg) cells that may have different functional characteristics or synergistic roles. All-trans retinoic acid (atRA), a vitamin A metabolite, regulates a wide range of biological processes, including cell differentiation and proliferation. Recent studies demonstrated that atRA also regulates the differentiation of T helper (Th) cells and Treg cells. Moreover, atRA also sustains nTreg stability under inflammatory conditions. In this review, we summarize the significant progress of our understanding of the role(s) and mechanisms of atRA in Treg biology.


Assuntos
Fatores de Transcrição Forkhead/metabolismo , Linfócitos T Reguladores/imunologia , Linfócitos T Reguladores/metabolismo , Tretinoína/metabolismo , Animais , Humanos , Imunomodulação/efeitos dos fármacos , Subpopulações de Linfócitos/efeitos dos fármacos , Subpopulações de Linfócitos/imunologia , Modelos Imunológicos , Linfócitos T Reguladores/efeitos dos fármacos , Tretinoína/farmacologia
16.
Chem Commun (Camb) ; 51(9): 1647-9, 2015 Jan 31.
Artigo em Inglês | MEDLINE | ID: mdl-25503572

RESUMO

A calixarene-based supramolecular hydrogel with a porous network structure was successfully constructed via a hierarchical induced assembly strategy, showing reversible or irreversible gelation behaviors in response to several external stimuli including thermal, redox and ionic strength.


Assuntos
Calixarenos/química , Poliaminas/química , Tensoativos/química , Hidrogel de Polietilenoglicol-Dimetacrilato , Concentração de Íons de Hidrogênio , Modelos Moleculares , Oxirredução , Temperatura Ambiente
17.
Mol Med Rep ; 11(2): 1174-80, 2015 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-25370481

RESUMO

Morphine is used to relieve pain in patients with cancer in terminal phases. Dickkopf­1 (DKK1), a secreted protein, is a negative regulator of the Wnt/ß­catenin signaling pathway. Morphine and DKK1 are associated with tumorigenesis. However, to the best of our knowledge, there is no study evaluating the effects of these two factors simultaneously. In the present study, the effects of morphine and DKK1 on neuroblastoma cells in vivo and in vitro were evaluated. To establish the in vitro effects of DKK1 and morphine, human neuroblastoma SH­SY5Y cells were transfected with a DKK1­expressing plasmid and cell migration, apoptosis, migration and invasion were evaluated prior to and following morphine treatment. The results indicated that DKK1 induced apoptosis and inhibited the mobility of neuroblastoma cells and that morphine attenuated these DKK1­induced effects. To evaluate the effects of DKK1 and morphine in vivo, a mouse model of neuroblastoma was established, where mice bearing tumors of native SH-SY5Y cells were injected with DKK1. Tumor size, spatial memory and survival rate were investigated in untreated, DKK1­treated and DKK1+morphine­treated mice. Water maze and T­maze tests were performed, which revealed that DKK1­treated mice exhibited a better memory than DKK1 + morphine­treated mice. The expression of DKK1 in established xenografted tumors was associated with decreased tumor size and an increased survival rate, whereas morphine reversed these effects. Furthermore, it was confirmed that morphine and DKK1 take effect, at least in part, via the Wnt/ß­catenin signaling pathway. The results of the present study indicate that morphine may protect neuroblastoma cells and thus, it may be used in neuroblastoma patients.


Assuntos
Apoptose/efeitos dos fármacos , Peptídeos e Proteínas de Sinalização Intercelular/metabolismo , Morfina/farmacologia , Entorpecentes/farmacologia , Animais , Linhagem Celular Tumoral , Movimento Celular/efeitos dos fármacos , Proliferação de Células/efeitos dos fármacos , Vetores Genéticos/metabolismo , Humanos , Peptídeos e Proteínas de Sinalização Intercelular/genética , Estimativa de Kaplan-Meier , Imagem por Ressonância Magnética , Memória de Curto Prazo/efeitos dos fármacos , Camundongos , Camundongos Nus , Neuroblastoma/metabolismo , Neuroblastoma/mortalidade , Neuroblastoma/patologia , Transplante Heterólogo , beta Catenina/metabolismo
18.
Mol Med Rep ; 9(5): 1813-9, 2014 May.
Artigo em Inglês | MEDLINE | ID: mdl-24604262

RESUMO

Schisandra chinensis is a well-known traditional medicinal herb. Acetaminophen is a commonly used over-the-counter analgesic and overdose of acetaminophen was the most frequent cause of acute liver failure. However, no studies have demonstrated the role of Schisandra chinensis in acetaminophen-induced acute liver failure to the best of our knowledge. In this study, an acute liver injury model was established in mice using acetaminophen. The protective role of Schisandra chinensis was detected by histopathological analysis, and measurement of the serum transaminase levels and hepatic Cyp activity levels in the mouse model. Subsequently, hepatocytes were isolated from the livers of the mouse model. The cell cycle, apoptosis, mitochondrial membrane potential and reactive oxygen species were determined using flow cytometry. Cell proliferation and 26S proteasome activity were determined using spectrophotometry. Schisandra chinensis was found to resist acetaminophen-induced hepatotoxicity by protecting mitochondria and lysosomes and inhibiting the phosphor-c-Jun N-terminal kinase signaling pathway. These findings provide a novel application of Schisandra chinensis against acetaminophen-induced acute liver failure.


Assuntos
Doença Hepática Induzida por Substâncias e Drogas/tratamento farmacológico , Doença Hepática Induzida por Substâncias e Drogas/metabolismo , Medicamentos de Ervas Chinesas/farmacologia , Schisandra/química , Acetaminofen/efeitos adversos , Animais , Modelos Animais de Doenças , Medicamentos de Ervas Chinesas/administração & dosagem , Hepatócitos/efeitos dos fármacos , Hepatócitos/metabolismo , Fígado/efeitos dos fármacos , Fígado/metabolismo , Fígado/patologia , Masculino , Camundongos
19.
Chemistry ; 20(14): 4023-31, 2014 Apr 01.
Artigo em Inglês | MEDLINE | ID: mdl-24574110

RESUMO

A water-soluble supramolecular polymer with a high degree of polymerization and viscosity has been constructed based on the strong host-guest interaction between p-sulfonatocalix[4]arenes (SC4As) and viologen. A homoditopic doubly ethyl-bridged bis(p-sulfonatocalix[4]arene) (d-SC4A) was prepared and its binding behavior towards methyl viologen compared with the singly ethyl-bridged bis(p-sulfonatocalix[4]arene) (s-SC4A) by NMR spectroscopy and isothermal titration calorimetry. By employing a viologen dimer (bisMV(4+)) as the homoditopic guest, two linear AA/BB-type supramolecular polymers, d-SC4A⊃bisMV(4+) and s-SC4A⊃bisMV(4+), were successfully constructed. Compared with s-SC4A⊃bisMV(4+), d-SC4A⊃bisMV(4+) shows much higher solubility and viscosity, and has also been characterized by viscosity, diffusion-ordered NMR spectroscopy, dynamic light scattering, and atomic force microscopy measurements. Furthermore, the polymer is responsive to electrostimulus as viologen is electroactive, which was studied by cyclic voltammetry. This study represents a proof-of-principle as the polymer can potentially be applied as a self-healing and degradable polymeric material.

20.
ACS Nano ; 8(2): 1609-18, 2014 Feb 25.
Artigo em Inglês | MEDLINE | ID: mdl-24467338

RESUMO

Self-assembled fluorescent nanoparticles responding to specific stimuli are highly appealing for applications such as labels, probes, memory devices, and logic gates. However, organic analogues are challenging to prepare, due to unfavorable aggregation-caused quenching. We herein report the preparation of self-assembled fluorescent organic nanoparticles in water by means of calixarene-induced aggregation of a tetraphenylethene derivative (QA-TPE) mediated by p-sulfonatocalix[4]arenes. The self-assembled nanoparticles showed interesting photoswitching behaviors, and the fluorescence output of the generated nanoparticles was opposite to that of free QA-TPE both before and after irradiation. Free QA-TPE is nonfluorescent, owing to intramolecular rotations of the phenyl rings. In contrast, the self-assembled nanoparticles that formed upon complexation of QA-TPE with p-sulfonatocalix[4]arene exhibited aggregation-induced emission fluorescence (λ(em) = 480 nm, Φ = 14%), as a result of the inhibition of rotations. Upon UV light irradiation, free QA-TPE was cyclized to the corresponding diphenylphenanthrene, which showed typical fluorescence of a π-conjugated system (λ(em) = 385 nm, Φ = 9.3%), whereas the nanoparticles were nonfluorescent upon irradiation due to the aggregation-caused quenching. In effect, this system allows programmed modulation of TPE fluorescence at two different emission wavelengths by means of host-guest complexation and irradiation. Relative to a single-mode stimulus-responsive system, our new developed system of highly integrated modes into a single molecular unit that can exhibit modulation of fluorescence by multiple stimulus is expected to be more adaptable for practical applications and to show enhanced multifunctionality.

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