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1.
Exp Eye Res ; 240: 109782, 2024 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-38199260

RESUMO

Dry eye disease (DED) is caused by a loss of homeostasis of the tear film, which results in visual disturbance, ocular surface inflammation and damage, and neurosensory abnormalities. Although it is prevalent in 5-50% of the global population, there are limited clinical options for its treatment. This study explored the potential use of human intravenous immunoglobulin (IVIg) and its enriched fractions of sialylation, sialylated IVIg (sIVIg), as a treatment for DED. Fifteen female New Zealand white rabbits were topically instilled with 0.2% benzalkonium chloride (BAC) twice daily for five consecutive days to induce experimental dry eye. Saline, 0.4% IVIg, or 0.04% sIVIg eye drops were instilled twice daily for 20 consecutive days. Clinical evaluations, such as non-invasive tear break-up time (NIBUT) and corneal fluorescein staining (CFS), were conducted. mRNA levels of mucin 4, mucin 16, TNF-α, IL-1ß, MMP9, IL-10, TGF-ß, and CD209 in rabbit conjunctival tissues were examined using reverse transcription polymerase chain reaction (RT-PCR) or quantitative RT-PCR (qRT-PCR). The relationships between CD209 family members in rabbits and various mammalian species were analyzed using a phylogenetic tree. IVIg or sIVIg treatment resulted in clinical improvements in the rabbit DED model. The inflammatory cytokines, TNF-α and IL-1ß, were increased and mucin 4 and mucin 16, cell surface-associated mucins, were decreased in BAC-induced dry eye. Following IVIg or sIVIg treatment, inflammatory cytokines decreased, whereas the anti-inflammatory cytokine, IL-10, increased substantially. Moreover, a 10-fold lower sIVIg treatment dose resulted in prolonged IL-10 production, representing a significantly improved DED compared to IVIg. Furthermore, the expression of rabbit CD209 mRNA in the rabbit conjunctiva and its close relationship with primate homologs suggest that it may interact with IVIg or sIVIg to promote IL-10 expression, as previously described in humans. At a lower dosage, sIVIg showed a more efficient improvement in DED, making it a promising new candidate medication for DED.


Assuntos
Citocinas , Síndromes do Olho Seco , Coelhos , Humanos , Animais , Citocinas/genética , Citocinas/metabolismo , Imunoglobulinas Intravenosas/uso terapêutico , Imunoglobulinas Intravenosas/metabolismo , Interleucina-10/efeitos adversos , Interleucina-10/metabolismo , Mucina-4/metabolismo , Fator de Necrose Tumoral alfa/metabolismo , Antígeno Ca-125 , Filogenia , Síndromes do Olho Seco/metabolismo , Lágrimas/metabolismo , Compostos de Benzalcônio , RNA Mensageiro/genética , RNA Mensageiro/metabolismo , Mamíferos
2.
Nano Lett ; 23(10): 4282-4289, 2023 May 24.
Artigo em Inglês | MEDLINE | ID: mdl-37167152

RESUMO

Excitons, electron-hole pairs in semiconductors, can be utilized as information carriers with a spin or valley degree of freedom. However, manipulation of excitons' motion is challenging because of their charge-neutral characteristic and short recombination lifetimes. Here we demonstrate electric-field-driven drift and funneling of charged excitons (i.e., trions) toward the center of a MoSe2 monolayer. Using a simple bottom-gate device, we control the electric fields in the vicinity of the suspended monolayer, which increases the trion density and pulls down the layer. We observe that locally excited trions are subjected to electric force and, consequently, drift toward the center of the stretched layer. The exerting electric force on the trion is estimated to be 102-104 times stronger than the strain-induced force in the stretched monolayer, leading to the successful observation of trion drift under continuous-wave excitation. Our findings provide a new route for manipulating trions and achieving new types of optoelectronic devices.

3.
Clin Immunol ; 246: 109215, 2023 01.
Artigo em Inglês | MEDLINE | ID: mdl-36581222

RESUMO

Although the use of IVIg has increased in various immune-driven diseases and even in pregnancy, the exact action mechanisms of IVIg are not fully understood. Dendritic cell-specific intercellular adhesion molecule-3 grabbing non-integrin (DC-SIGN) is a known receptor for α-2,6-sialylated IgG (sIVIg), which is responsible for the anti-inflammatory effect of IVIg. DC-SIGN is expressed on Hofbauer cells (HBCs) of the fetal villi of the placenta which act as an innate immune modulator at the maternal-fetal interface. Preeclampsia is a major complication in pregnancy and is related to IL-10, a cytokine with an important role in immune tolerance. DC-SIGN interaction with sIVIg in HBCs promoted IL-10 secretion through the activation of the caveolin-1/NF-κB pathway, especially in plasma lipid rafts. Consistent results were obtained for HBCs from patients with preeclampsia. Collectively, the stimulation of DC-SIGN+ HBCs with sIVIg enhanced immune tolerance in the feto-maternal environment, suggesting the therapeutic application of sIVIg to prevent preeclampsia.


Assuntos
Imunoglobulinas Intravenosas , Pré-Eclâmpsia , Gravidez , Feminino , Humanos , Imunoglobulinas Intravenosas/uso terapêutico , NF-kappa B/metabolismo , Interleucina-10/metabolismo , Caveolina 1/metabolismo , Lectinas Tipo C/metabolismo , Tolerância Imunológica , Células Dendríticas
4.
Opt Express ; 25(6): 6215-6226, 2017 Mar 20.
Artigo em Inglês | MEDLINE | ID: mdl-28380974

RESUMO

The waveguiding of surface enhanced Raman scattering (SERS) signals was demonstrated by using organic semiconducting microrods (MRs) hybridized with functionalized gold nanoparticles (Au-NPs). Organic semiconducting 1,4-bis(3,5-bis(trifluoromethyl) styryl)-2,5-dibromobenzene (TSDB) crystalline MRs were fabricated as active optical waveguiding system using a self-assembly method. The static SERS effect and the enhancement of photoluminescence were simultaneously observed for the TSDB MRs hybridized with Au-NPs. The waveguiding characteristics of the SERS signals through the hybrid MR of TSDB/Au-NPs were investigated using a high-resolution laser confocal microscope (LCM) system. The enhanced output Raman characteristic modes of TSDB molecules were clearly observed along the hybrid MR of TSDB/Au-NPs, which is attributed to stronger scattering of the light and the increased coupling efficiency of waveguiding due to the presence of Au-NPs. The waveguiding of the SERS signals exhibited different decay constants for the corresponding characteristic Raman modes, such as -C = C- aromatic, -CF3, and C-Br stretching modes. The observed waveguiding characteristics of various SERS modes enable multi-modal waveguiding with relatively narrow spectral resolution for nanophotonic information.

5.
Nanotechnology ; 28(43): 435501, 2017 Oct 27.
Artigo em Inglês | MEDLINE | ID: mdl-28841139

RESUMO

Layered transition metal dichalcogenides, such as MoS2, WSe2 and WS2, are exciting two-dimensional (2D) materials because they possess tunable optical and electrical properties that depend on the number of layers. In this study, the nanoscale photoluminescence (PL) characteristics of the p-type WSe2 monolayer, and WSe2 layers hybridized with the fluorescent dye Cy3 attached to probe-DNA (Cy3/p-DNA), have been investigated as a function of the concentration of Cy3/DNA by using high-resolution laser confocal microscopy. With increasing concentration of Cy3/p-DNA, the measured PL intensity decreases and its peak is red-shifted, suggesting that the WSe2 layer has been p-type doped with Cy3/p-DNA. Then, the PL intensity of the WSe2/Cy3/p-DNA hybrid system increases and the peak is blue-shifted through hybridization with relatively small amounts of target-DNA (t-DNA) (50-100 nM). This effect originates from charge and energy transfer from the Cy3/DNA to the WSe2. For t-DNA detection, our systems using p-type WSe2 have the merit in terms of the increase of PL intensity. The p-type WSe2 monolayers can be a promising nanoscale 2D material for sensitive optical bio-sensing based on the doping and de-doping responses to biomaterials.


Assuntos
Técnicas Biossensoriais , DNA/análise , Medições Luminescentes/métodos , Dispositivos Ópticos , Compostos de Selênio/química , Compostos de Tungstênio/química , Pareamento de Bases , Carbocianinas/química , DNA/química , Sondas de DNA/química , Transferência de Energia , Corantes Fluorescentes/química , Luminescência , Hibridização de Ácido Nucleico
6.
Nanotechnology ; 28(18): 185702, 2017 May 05.
Artigo em Inglês | MEDLINE | ID: mdl-28319028

RESUMO

Organic/inorganic hybrid structures have been widely studied because of their enhanced physical and chemical properties. Monolayers of transition metal dichalcogenides (1L-TMDs) and organic nanoparticles can provide a hybridization configuration between zero- and two-dimensional systems with the advantages of convenient preparation and strong interface interaction. Here, we present such a hybrid system made by dispersing π-conjugated organic (tris (8-hydroxyquinoline) aluminum(III)) (Alq3) nanoparticles (NPs) on 1L-MoS2. Hybrids of Alq3 NP/1L-MoS2 exhibited a two-fold increase in the photoluminescence of Alq3 NPs on 1L-MoS2 and the n-doping effect of 1L-MoS2, and these spectral and electronic modifications were attributed to the charge transfer between Alq3 NPs and 1L-MoS2. Our results suggested that a hybrid of organic NPs/1L-TMD can offer a convenient platform to study the interface interactions between organic and inorganic nano objects and to engineer optoelectronic devices with enhanced performance.

7.
Small ; 12(9): 1154-8, 2016 Mar 02.
Artigo em Inglês | MEDLINE | ID: mdl-26651134

RESUMO

A novel protein recognition platform is developed using aptamer-linked polythiophene nanowires. As the aptamer functionalized poly (3-methylthiophene) nanowire is treated by the specific protein, resonance Raman and photoluminescence signals are simultaneously enhanced. Statistical analyses deliver the capability of a single conjugated polymer nanowire with phase-transition characteristics in response to selectivity and concentration.


Assuntos
Aptâmeros de Peptídeos/química , Nanofios/química , Transição de Fase , Polímeros/química , Tiofenos/química , Trombina/química , Microscopia Confocal , Fator de Crescimento Derivado de Plaquetas , Espectrofotometria Ultravioleta , Análise Espectral Raman
8.
Opt Express ; 24(24): 27546-27553, 2016 Nov 28.
Artigo em Inglês | MEDLINE | ID: mdl-27906325

RESUMO

Two-dimensional (2-D) transition metal dichalcogenides, such as MoS2, WSe2, and WS2, are promising materials for application in field effect transistors, optoelectronics, and sensing devices. In this study, 2-D WSe2 samples with various numbers of layers were hybridized with functionalized gold nanoparticles (Au-NPs) to achieve surface-enhanced Raman scattering (SERS). The nanoscale Raman and photoluminescence spectra of the WSe2 layers and WSe2/Au-NP hybrids were measured using a high-resolution laser confocal microscope. The WSe2 exhibited distinct optical characteristics depending on the number of WSe2 layers. The intensities of the Raman characteristic modes of the WSe2 layers were significantly enhanced after hybridization with functionalized Au-NPs, indicating the SERS effect. The SERS effect weakened with increasing the number of WSe2 layers. The SERS effect was more pronounced for mono- and bi-layer WSe2 systems compared with the multi-layer WSe2 systems.

9.
Adv Sci (Weinh) ; 10(14): e2207653, 2023 May.
Artigo em Inglês | MEDLINE | ID: mdl-36938849

RESUMO

Interlayer excitons (IXs) at the interface of heterostructures (HSs) with a staggered band alignment are fascinating quantum quasi-particles with light-emitting and long-lifetime characteristics. In this study, the energy band alignments (EBAs) of the HS of MAPbI3 perovskite thin sheets with CdSe-ZnS core-shell quantum dot (QD) layers are modulated by using different diameters of the QDs. Far-red IX emission is observed at 1.42 eV from the HS of MAPbI3 /CdSe-ZnS-QD (λem  = 645 nm) with type-II EBA owing to charge transfer. The lifetime of the far-red IXs is estimated to be 5.68 µs, which is considerably longer than that (0.715 ns) of the intralayer excitons from CdSe-ZnS-QD. With increasing incident excitation power, the PL peak and its intensity of IXs are blue-shifted and linearly increased, respectively, indicating a strong dipole alignment of far-red IXs at the heterojunction. Back focal plane imaging suggests that the directions of dipole moments of the IXs are relatively out-of-plane compared to those of the intralayer excitons (MAPbI3 and CdSe-ZnS-QD). Notably, the abnormal behavior of the optical characteristics is observed near the phase transition temperature (90 K) of MAPbI3 . MAPbI3 /CdSe-ZnS-QD HS photodetectors show the increase in photocurrent and detectivity compared to MAPbI3 at IX excitation.

10.
Nat Commun ; 14(1): 7190, 2023 Nov 08.
Artigo em Inglês | MEDLINE | ID: mdl-37938244

RESUMO

The dipole characteristics of Frenkel excitons and charge-transfer excitons between donor and acceptor molecules in organic heterostructures such as exciplexes are important in organic photonics and optoelectronics. For the bilayer of the organic donor 4,4',4''-tris[(3-methylphenyl)phenylamino]triphenylamine and acceptor 2,4,6-tris(biphenyl-3-yl)-1,3,5-triazine molecules, the exciplexes form aligned dipoles perpendicular to the Frenkel excitons, as observed in back focal plane photoluminescence images. The angular chromism of exciplexes observed in the 100 meV range indicates possible delocalization and angle-sensing photonic applications. The blue shift of the peak position and increase in the linewidth of photoluminescene spectra with increasing excitation power are caused by the repulsive aligned exciplex dipole moments with a long lifetime (4.65 µs). Electroluminescence spectra of the exciplex from organic light-emitting diodes using the bilayer are blue-shifted with increasing bias, suggesting unidirectional alignment of the exciplex dipole moments. The observation of exciplex dipole moment alignments across molecular interfaces can facilitate the controlled coupling of exciton species and increase efficiency of organic light-emitting diodes.

11.
Langmuir ; 28(29): 10948-55, 2012 Jul 24.
Artigo em Inglês | MEDLINE | ID: mdl-22746296

RESUMO

A new functionalized triethoxysilane bearing an X-shaped, anthracene-based semiconducting molecule on one arm was designed and synthesized as a precursor for the preparation of a self-assembled monolayer (SAM) on a SiO(2) substrate. 3-Isocyanatopropyl triethoxysilane was reacted with a monohydroxyl-terminated X-shaped, anthracene-based semiconducting molecule in the presence of tin catalyst. The 6-(5-((6-((5-hexylthiophen-2-yl)ethynyl)-9,10-bis(phenylethynyl)anthracen-2-yl)ethynyl)thiophen-2-yl)hexyl 3-(triethoxysilyl)propylcarbamate (BATHT-TEOS) was found to be stable and sufficiently reactive to form organic monolayers on hydroxylated SiO(2) surfaces. The structures and properties of these SAMs were investigated using X-ray photoelectron spectroscopy, UV-vis absorption spectroscopy, photoluminescence (PL) spectroscopy, laser scanning confocal microscopy-PL spectrometry, and spectroscopic ellipsometry. In this work, BATHT-SAM was employed as an interfacial layer on SiO(2) to fabricate ultrathin film transistors (UTFTs, active layer thickness ∼ 16.09 nm). The device UTFT-I, made of 0.06 wt % 5,5'-(9,10-bis(phenylethynyl)anthracene-2,6-diyl)bis(ethyne-2,1-diyl)bis(2-hexylthiophene) (BATHT) solution on an n-octyltrichlorosilane-SAM/SiO(2) layer, showed no gate effect for the carrier transport behavior; however, the device UTFT-II, fabricated on BATHT-SAM/SiO(2), exhibited field effect mobilities of 0.04 cm(2) V(-1) s(-1) (I(on/off) ∼ 6.3 × 10(3) to 1.0 × 10(4)). This can be attributed to the effect of BATHT-SAM inducing uniform coverage and ordering of BATHT molecules as an upper layer.


Assuntos
Antracenos/química , Antracenos/síntese química , Silanos/química , Silanos/síntese química , Transistores Eletrônicos , Estrutura Molecular
12.
Sci Technol Adv Mater ; 12(2): 025002, 2011 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-27877384

RESUMO

Poly(3-hexylthiophene) (P3HT) nanoparticles (NPs) were prepared by a reprecipitation method. Hydrothermal processing applied external pressure to the pristine P3HT NPs at temperatures ranging from 60 to 150 °C. Optical absorption and photoluminescence (PL) spectra for the hydrothermally treated P3HT NPs varied markedly with the processing temperature. With increasing treatment temperature, the absorption peak broadened and the peak position shifted from 510 to 623 nm; moreover, the intensity ratio of the 0-1 to 0-0 emission varied. These changes were caused by interactions between the P3HT main chains and alkyl side groups and conformational modifications induced by the high pressure during the hydrothermal process. The evolution of the optical absorption spectra of the P3HT NPs during the hydrothermal processing was strongly correlated with the variation of PL excitation spectra and with the PL emission spectra of a single NP.

13.
Chem Soc Rev ; 39(7): 2439-52, 2010 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-20514379

RESUMO

Pi-conjugated organic systems have been used as optoelectronic and sensing materials due to their characteristics of efficient light emission or absorption, and p-type charge transport. The hybrid nanostructures of pi-conjugated organic systems with nanoscale metals offer surface plasmon (SP)-enhanced luminescence, which can be applied to organic-based optoelectronics, photonics, and sensing. Various hybrid nanostructures using light-emitting polymers with nanoscale metals have been fabricated and have shown considerable enhancement of photoluminescence efficiency due to energy and charge transfer effects in SP resonance coupling. In this tutorial review, recent conceptual and technological achievements in light-emitting polymers-based hybrid nanostructures are described.


Assuntos
Luminescência , Nanoestruturas/química , Nanotecnologia/métodos , Ressonância de Plasmônio de Superfície/métodos , Quimera , Luz , Metais/química , Óptica e Fotônica/métodos , Compostos Orgânicos , Polímeros/química
14.
ACS Appl Mater Interfaces ; 13(34): 40880-40890, 2021 Sep 01.
Artigo em Inglês | MEDLINE | ID: mdl-34424668

RESUMO

The characteristics of field effect transistors (FETs) fabricated using two-dimensional (2D) transition-metal dichalcogenides (TMDCs) can be modulated by surface treatment of the active layers. In this study, an ionic π-conjugated polyelectrolyte, poly(9,9-bis(4'-sulfonatobutyl)fluorene-alt-1,4-phenylene) potassium (FPS-K), was used for the surface treatment of MoSe2 and WS2 FETs. The photoluminescence (PL) intensities of monolayer (1L)-MoSe2 and 1L-WS2 clearly decreased, and the PL peaks were red-shifted after FPS-K treatment, suggesting a charge-transfer effect. In addition, the n-channel current of both the MoSe2 and WS2 FETs increased and the threshold voltage (Vth) shifted negatively after FPS-K treatment owing to the charge-transfer effect. The photoresponsivity of the MoSe2 FET under light irradiation (λex = 455 nm) increased considerably, from 5300 A W-1 to approximately 10 000 A W-1, after FPS-K treatment, and similar behavior was observed in the WS2 FET. The results can be explained in terms of the increase in electron concentration due to photogating. The external quantum efficiency and photodetectivity of both FETs were also enhanced by the charge-transfer effect resulting from surface treatment with FPS-K containing mobile cations (K+) and fixed anions (SO3-), as well as by the photogating effect. The variation in charge-carrier density due to the photogating and charge-transfer effects is estimated to be approximately 2 × 1012 cm-2. The results suggest that π-conjugated polyelectrolytes such as FPS-K can be a promising candidate for the passivation of TMDC-based FETs and obtaining enhanced photoresponsivity.

15.
Am J Pathol ; 174(3): 1017-26, 2009 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-19179610

RESUMO

Epidemiological and preclinical observations have suggested a role for one or more products of the mevalonate/cholesterol biosynthesis pathway in the progression of prostate cancer. In this study, we used ezetimibe (Zetia), a specific, FDA-approved, cholesterol uptake-blocking drug, in combination with either a hyper- or hypocholesterolemic diet, to show that elevated circulating cholesterol levels promote, whereas a reduction in circulating cholesterol levels retard, the growth of human prostate cancer xenograft tumors in mice. Circulating cholesterol levels also modified tumor angiogenesis; higher cholesterol levels increased microvessel density and other indicators of vascularity. Consistent with these data, the reduction of cholesterol levels also increased the levels of the angiogenesis inhibitor thrombospondin-1 in the xenografts. Our results thus suggest that hypercholesterolemia directly accelerates the growth of prostate carcinomas, and that the pharmacological reduction of serum cholesterol levels may retard prostate cancer growth by inhibiting tumor angiogenesis.


Assuntos
Antineoplásicos/uso terapêutico , Azetidinas/uso terapêutico , Neovascularização Patológica/prevenção & controle , Neoplasias da Próstata/patologia , Animais , Anticolesterolemiantes/uso terapêutico , Apoptose/efeitos dos fármacos , Morte Celular/efeitos dos fármacos , Colesterol/farmacologia , Ezetimiba , Hemoglobinas/metabolismo , Humanos , Masculino , Camundongos , Microcirculação/efeitos dos fármacos , Transplante de Neoplasias , Neoplasias da Próstata/tratamento farmacológico , Transplante Heterólogo
16.
ACS Appl Mater Interfaces ; 12(32): 36530-36539, 2020 Aug 12.
Artigo em Inglês | MEDLINE | ID: mdl-32672032

RESUMO

The electrical and optical characteristics of two-dimensional (2D) transition-metal dichalcogenides (TMDCs) can be improved by surface modification. In this study, distinctive field-effect transistors (FETs) were realized by forming cross-type 2D WSe2/MoS2 p-n heterojunctions through surface treatment using poly(methyl methacrylate-co-methacrylic acid) (PMMA-co-PMAA). The FETs were applied to new ternary inverters as multivalued logic circuits (MVLCs). Laser confocal microscope photoluminescence spectroscopy indicated the generation of trions in the WSe2 and MoS2 layers, and the intensity decreased after PMMA-co-PMAA treatment. For the cross-type WSe2/MoS2 p-n heterojunction FETs subjected to PMMA-co-PMAA treatment, the channel current and the region of anti-ambipolar transistor characteristics increased considerably, and ternary inverter characteristics with three stable logic states, "1", "1/2", and "0", were realized. Interestingly, the intermediate logic state 1/2, which results from the negative differential transconductance characteristics, was realized by the turn-on of all component FETs, as the current of the FETs increased after PMMA-co-PMAA treatment. The electron-rich carboxyl acid moieties in PMMA-co-PMAA can undergo coordination with the metal Mo or W atoms present in the Se or S vacancies, respectively, resulting in the modulation of charge density. These features yielded distinctive FETs and ternary inverters for MVLCs using cross-type WSe2/MoS2 heterojunctions.

17.
ACS Appl Mater Interfaces ; 12(22): 25159-25167, 2020 Jun 03.
Artigo em Inglês | MEDLINE | ID: mdl-32390418

RESUMO

Perovskite CsPbX3 (X = Br, Cl, and I) nanostructures have been intensively studied as they are luminescent, photovoltaic, and photosensitizing active materials. Two-dimensional (2D) transition-metal dichalcogenides (TMDCs) with MX2 (M = Mo, W; X = S, Se, Te, etc.) structures have been used in flexible optoelectronic devices. In this study, perovskite green-light-emitting CsPbBr2I1 quantum dots (QDs) and blue-light-emitting CsPb(Cl/Br)3-QDs are utilized to enhance the photoresponsive characteristics of 2D MSe2 (M = Mo and W)-based field-effect transistors (FETs). From laser confocal microscopy photoluminescence (PL) experiments, PL quenching of the perovskite CsPb(Cl/Br)3-QDs and CsPbBr2I1-QDs is observed after hybridization with MoSe2 and WSe2 layers, respectively, which reflects the charge-transfer effect. According to the characteristics of the FETs based on the WSe2, MoSe2, WSe2/CsPbBr2I1-QDs hybrid, and MoSe2/CsPb(Cl/Br)3-QDs hybrid, the p-channel current (with hole mobility) is considerably decreased after the hybridization with the QDs. Notably, under incident light, the n-channel photocurrent and photoresponsivity of the FET are substantially increased, and the threshold voltage is negatively shifted owing to the hybridization with the perovskite QDs. The results show that the photosensitive n-type doping effect on the 2D MoSe2 and WSe2 nanosystems originates from the photogating effect by the trap states after the hybridization with various perovskite CsPbX3-QDs.

18.
J Nanosci Nanotechnol ; 9(5): 3112-8, 2009 May.
Artigo em Inglês | MEDLINE | ID: mdl-19452977

RESUMO

The enhanced nanometer-scale photoluminescence (PL) and quantum yield of hybrid double layered nanotubes (HDLNTs) consisting of a light-emitting poly(3-methylthiophene) (P3MT) nanotube coated with nanometer-scale copper (Cu) metal were observed and presented. The HDLNTs of the Cu coated P3MT (P3MT/Cu) were synthesized through a sequential electrochemical synthetic method in an anodic alumina oxide (Al2O3) nanoporous template. We confirmed that the Cu nanotubes were covered outside the light emitting P3MT nanotubes based a high resolution transmission electron microscope image. From laser confocal microscope (LCM) PL experiments of an isolated single strand of the P3MT nanotubes and of their HDLNTs, we observed a -100 times enhancement of the PL peak intensity for the HDLNTs of P3MT/Cu compared to that of the P3MT single nanotube, which was qualitatively confirmed through the measurement of the quantum yield. The energy and/or charge transfer effects in surface plasmon resonance contributed to the larger enhancement of the PL efficiency of the hybrid P3MT/Cu nanotubes. The PL decay life-time of the excitons of the P3MT nanotubes using a time resolved PL was not changed after the formation of the HDLNTs, implying that the PL enhancement of the hybrid nanotubes might have originated from fluorescence, not phosphorescence.

19.
J Nanosci Nanotechnol ; 8(4): 1559-81, 2008 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-18572558

RESUMO

This review aims at reporting on interesting and potential aspects of conducting polymer/clay nanocomposites with regard to their preparation, characteristics and engineering applications. Various conducting polymers such as polyaniline, polypyrrole and copolyaniline are introduced and three different preparation methods of synthesizing conducting polymer/clay nanocomposites are being emphasized. Morphological features, structure characteristics and thermal degradation behavior are explained based on SEM/TEM images, XRD pattern analyses and TGA/DSC graphs, respectively. Attentions are also being paid on conductive/magnetic performances as well as two potential applications in anti-corrosion coating and electrorheological (ER) fluids.


Assuntos
Silicatos de Alumínio/química , Cristalização/métodos , Eletroquímica/métodos , Nanoestruturas/química , Nanoestruturas/ultraestrutura , Nanotecnologia/métodos , Polímeros/química , Argila , Condutividade Elétrica , Substâncias Macromoleculares/química , Teste de Materiais , Conformação Molecular , Tamanho da Partícula , Propriedades de Superfície
20.
ACS Appl Mater Interfaces ; 10(38): 32556-32566, 2018 Sep 26.
Artigo em Inglês | MEDLINE | ID: mdl-30183249

RESUMO

An n-type MoS2 monolayer grown by chemical vapor deposition method was partially hybridized with an organic semiconducting p-type tetracene thin film. The photoluminescence (PL) intensity in the hybrid region of the MoS2/tetracene is clearly lower than that of pristine tetracene because of the charge-transfer effect, which was confirmed by the decrease in exciton lifetimes. Decrease in the temperature led to blue-shift in the PL peak position of MoS2 layers and, consequently, the PL intensities of both tetracene and MoS2 considerably increased owing to the decrease in phonon interaction. The PL spectra of bound excitons in the hybrid region were clearly observed at low temperatures, indicating the formation of trap states. The lateral-type n-p heterojunction field-effect transistors (FETs) using the MoS2/tetracene hybrid as an active layer showed gate-tunable rectification I- V and anti-ambipolar field-effect characteristics with hysteresis effect. The charge transport characteristics across the n-p heterojunction of the hybrid region of the FET can be explained in terms of the Shockley-Read-Hall trap-intermediated tunneling and Langevin recombination mechanisms. To improve the performance of MoS2/tetracene-based FET, a dielectric hexagonal boron nitride (h-BN) thin layer was inserted between the SiO2 surface and the active MoS2 layer. We observed the decrease in the hysteresis effect and threshold voltage of the h-BN/MoS2/tetracene-based FETs due to the decrease in the number of traps at the interface. The performance of h-BN/MoS2/tetracene FET device was also enhanced after the annealing process.

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