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1.
Nat Commun ; 10(1): 3789, 2019 Aug 22.
Artigo em Inglês | MEDLINE | ID: mdl-31439836

RESUMO

ProMyelocyticLeukemia (PML) protein can polymerize into a mega-Dalton nuclear assembly of 0.1-2 µm in diameter. The mechanism of PML nuclear body biogenesis remains elusive. Here, PMLRBCC is successfully purified. The gel filtration and ultracentrifugation analysis suggest a previously unrecognized sequential oligomerization mechanism via PML monomer, dimer, tetramer and N-mer. Consistently, PML B1-box structure (2.0 Å) and SAXS characterization reveal an unexpected networking by W157-, F158- and SD1-interfaces. Structure-based perturbations in these B1 interfaces not only impair oligomerization in vitro but also abolish PML sumoylation and nuclear body biogenesis in HeLaPml-/- cell. More importantly, as demonstrated by in vivo study using transgenic mice, PML-RARα (PR) F158E precludes leukemogenesis. In addition, single cell RNA sequencing analysis shows that B1 oligomerization is an important regulator in PML-RARα-driven transactivation. Altogether, these results not only define a previously unrecognized B1-box oligomerization in PML, but also highlight oligomerization as an important factor in carcinogenesis.

2.
ACS Nano ; 2019 Aug 02.
Artigo em Inglês | MEDLINE | ID: mdl-31361122

RESUMO

Polarization-sensitive photodetection in a broad spectrum range is highly desired due to the great significance in military and civilian applications. Palladium diselenide (PdSe2), a newly explored air-stable, group 10 two-dimensional (2D) noble metal dichalcogenide with a puckered pentagonal structure, holds promise for polarization-sensitive photodetection. Herein, we report a highly polarization-sensitive, broadband, self-powered photodetector based on graphene/PdSe2/germanium heterojunction. Owing to the enhanced light absorption of the mixed-dimensional van der Waals heterojunction and the effective carrier collection with graphene transparent electrode, the photodetector exhibits superior device performance in terms of a large photoresponsivity, a high specific detectivity, a fast response speed to follow nanosecond pulsed light signal, and a broadband photosensitivity ranging from deep ultraviolet (DUV) to mid-infrared (MIR). Significantly, highly polarization-sensitive broadband photodetection with an ultrahigh polarization sensitivity of 112.2 is achieved, which represents the best result for 2D layered material-based photodetectors. Further, we demonstrated the high-resolution polarization imaging based on the heterojunction device. This work reveals the great potential of 2D PdSe2 for high-performance, air-stable, and polarization-sensitive broadband photodetectors.

3.
Nanoscale ; 10(32): 15285-15293, 2018 Aug 16.
Artigo em Inglês | MEDLINE | ID: mdl-30067253

RESUMO

Two-dimensional group-10 transition metal dichalcogenides have recently attracted increasing research interest because of their unique electronic and optoelectronic properties. Herein, we present vertical hybrid heterojunctions of multilayered PtSe2 and Si, which take advantage of large-scale homogeneous PtSe2 films grown directly on Si substrates. These heterojunctions show obvious rectifying behavior and a pronounced photovoltaic effect, enabling them to function as self-driven photodetectors operating at zero bias. The photodetectors can operate in both photovoltage and photocurrent modes, with responsivity values as high as 5.26 × 106 V W-1 and 520 mA W-1 at 808 nm, respectively. The Ilight/Idark ratio, specific detectivity, and response speed are 1.5 × 105, 3.26 × 1013 Jones, and 55.3/170.5 µs, respectively. Furthermore, the heterojunctions are highly sensitive in a broad spectral region ranging from deep ultraviolet to near-infrared (NIR) (200-1550 nm). Because of the strong NIR light absorption of PtSe2, the heterojunctions exhibit photocurrent responsivities of 33.25 and 0.57 mA W-1 at telecommunication wavelengths of 1310 and 1550 nm, respectively. Considering the excellent performance of the PtSe2/Si heterojunctions, they are highly suitable for application in high-performance broadband photodetectors. The generality of the above results also signifies that the proposed in situ synthesis method has great potential for future large-scale optoelectronic device integration.

4.
Opt Express ; 26(10): 13055-13060, 2018 May 14.
Artigo em Inglês | MEDLINE | ID: mdl-29801338

RESUMO

Numerous studies have been conducted to explore the performance of two-dimensional (2D) layered nano-materials based saturable absorber (SA) for pulsed laser applications. However, fabricating materials in nanoscale requires complicated preparation processes, high energy consumption, and high expertise. Hence, the study of pulsed laser performance based on the saturable absorber prepared by layered materials with bulk-micro size have gained a great attention. Platinum disulfide (PtS2), which is newly developed group 10 2D layered materials, offers great potential for the laser photonic applications owing to its high carrier mobility, broadly tunable natural bandgap energy, and stability. In this work, the first passively Q-switched Erbium (Er) doped fiber laser is demonstrated with an operational wavelength of 1568.8 nm by using PtS2 microflakes saturable absorber, fabricated by a simple liquid exfoliation in N-Methyl-2-pyrrolidone (NMP) and then incorporated into polyvinyl alcohol (PVA) polymer thin film. A stable Q-switched laser operation is achieved by using this PtS2-SA within a fiber laser ring cavity. The maximum average output power is obtained as 1.1 mW, corresponding to the repetition rate of 24.6 kHz, the pulse duration of 4.2 µs, and single pulse energy of 45.6 nJ. These results open up new applications of this novel PtS2 layered material.

5.
Elife ; 62017 11 10.
Artigo em Inglês | MEDLINE | ID: mdl-29125121

RESUMO

Pili are critical in host recognition, colonization and biofilm formation during bacterial infection. Here, we report the crystal structures of SafD-dsc and SafD-SafA-SafA (SafDAA-dsc) in Saf pili. Cell adherence assays show that SafD and SafA are both required for host recognition, suggesting a poly-adhesive mechanism for Saf pili. Moreover, the SafDAA-dsc structure, as well as SAXS characterization, reveals an unexpected inter-molecular oligomerization, prompting the investigation of Saf-driven self-association in biofilm formation. The bead/cell aggregation and biofilm formation assays are used to demonstrate the novel function of Saf pili. Structure-based mutants targeting the inter-molecular hydrogen bonds and complementary architecture/surfaces in SafDAA-dsc dimers significantly impaired the Saf self-association activity and biofilm formation. In summary, our results identify two novel functions of Saf pili: the poly-adhesive and self-associating activities. More importantly, Saf-Saf structures and functional characterizations help to define a pili-mediated inter-cellular oligomerizaiton mechanism for bacterial aggregation, colonization and ultimate biofilm formation.


Assuntos
Proteínas de Bactérias/química , Proteínas de Bactérias/metabolismo , Biofilmes/crescimento & desenvolvimento , Fímbrias Bacterianas/fisiologia , Salmonella typhimurium/fisiologia , Aderência Bacteriana , Cristalografia por Raios X , Modelos Moleculares , Ligação Proteica , Conformação Proteica , Multimerização Proteica
6.
Opt Lett ; 42(17): 3335-3338, 2017 Sep 01.
Artigo em Inglês | MEDLINE | ID: mdl-28957098

RESUMO

Polycrystalline 2D layered molybdenum disulfide (MoS2) films were synthesized via a thermal decomposition method. The MoS2/Si heterostructures were constructed in situ by synthesis MoS2 on plane Si substrates. Such MoS2/Si heterostructures exhibited high sensitivity to light illumination with wavelengths ranging from the deep ultraviolet to the near infrared. Photoresponse analysis reveals that a high responsivity of 23.1 A/W, a specific detectivity of 1.63×1012 Jones, and a fast response speed of 21.6/65.5 µs were achieved. Notably, the MoS2/Si heterojunction photodetector could operate with excellent stability and repeatability over a wide frequency range up to 150 kHz. The high performance could be attributed to the high-quality heterojunction between MoS2 and Si obtained by the in situ fabrication process. Such high performance with broadband response suggests that MoS2/Si heterostructures could have great potential in optoelectronic applications.

7.
Sci Rep ; 6: 20343, 2016 Jan 29.
Artigo em Inglês | MEDLINE | ID: mdl-26822972

RESUMO

The two-dimensional layered semiconducting tungsten disulfide (WS2) film exhibits great promising prospects in the photoelectrical applications because of its unique photoelectrical conversion property. Herein, in this paper, we report the simple and scalable fabrication of homogeneous, large-size and transferable WS2 films with tens-of-nanometers thickness through magnetron sputtering and post annealing process. The produced WS2 films with low resistance (4.2 kΩ) are used to fabricate broadband sensitive photodetectors in the ultraviolet to visible region. The photodetectors exhibit excellent photoresponse properties, with a high responsivity of 53.3 A/W and a high detectivity of 1.22 × 10(11) Jones at 365 nm. The strategy reported paves new way towards the large scale growth of transferable high quality, uniform WS2 films for various important applications including high performance photodetectors, solar cell, photoelectrochemical cell and so on.

8.
Nanoscale ; 7(42): 17771-7, 2015 Nov 14.
Artigo em Inglês | MEDLINE | ID: mdl-26456545

RESUMO

To control the optical properties of two-dimensional (2D) materials is a long-standing goal, being of both fundamental and technological significance. Tuning nonlinear optical absorption (NOA) properties of 2D transition metal dichalcogenides in a cost effective way has emerged as an important research topic because of its possibility to custom design NOA properties, implying enormous applications including optical computers, communications, bioimaging, and so on. In this study, WS2 with different size and thickness distributions was fabricated. The results demonstrate that both NOA onset threshold, F(ON), and optical limiting threshold, F(OL), of WS2 under the excitation of a nanosecond pulsed laser can be tuned over a wide range by controlling its size and thickness. The F(ON) and F(OL) show a rapid decline with the decrease of size and thickness. Due to the edge and quantum confinement effect, WS2 quantum dots (2.35 nm) exhibit the lowest F(ON) (0.01 J cm(-2)) and F(OL) (0.062 J cm(-2)) among all the samples, which are comparable to the lowest threshold achieved in graphene based materials, showing great potential as NOA materials with tunable properties.

9.
Opt Express ; 23(4): 4839-46, 2015 Feb 23.
Artigo em Inglês | MEDLINE | ID: mdl-25836518

RESUMO

A simple methyl-terminated (-CH(3)) surface passivation approach has been employed to enhance the performance of the bilayer graphene/Si nanohole array (BLG/SiNH array) Schottky junction based self-powered near infrared photodetector (SPNIRPD). The as-fabricated SPNIRPD exhibits high sensitivity to light at near infrared region at zero bias voltage. The I(light)/I(dark) ratio measured is 1.43 × 10(7), which is more than an order of magnitude improvement compared with the sample without passivation (~6.4 × 10(5)). Its corresponding responsivity and detectivity are 0.328 AW(-1) and 6.03 × 10(13) cmHz(1/2)W(-1), respectively. The demonstrated results have confirmed the high-performance SPNIRPD compared with the photo-detectors of similar type and its great potential application in future optoelectronic devices.

10.
ACS Nano ; 8(4): 4015-22, 2014 Apr 22.
Artigo em Inglês | MEDLINE | ID: mdl-24665986

RESUMO

Silicon nanostructure-based solar cells have lately intrigued intensive interest because of their promising potential in next-generation solar energy conversion devices. Herein, we report a silicon nanowire (SiNW) array/carbon quantum dot (CQD) core-shell heterojunction photovoltaic device by directly coating Ag-assisted chemical-etched SiNW arrays with CQDs. The heterojunction with a barrier height of 0.75 eV exhibited excellent rectifying behavior with a rectification ratio of 10(3) at ±0.8 V in the dark and power conversion efficiency (PCE) as high as 9.10% under AM 1.5G irradiation. It is believed that such a high PCE comes from the improved optical absorption as well as the optimized carrier transfer and collection capability. Furthermore, the heterojunction could function as a high-performance self-driven visible light photodetector operating in a wide switching wavelength with good stability, high sensitivity, and fast response speed. It is expected that the present SiNW array/CQD core-shell heterojunction device could find potential applications in future high-performance optoelectronic devices.

11.
Sci Rep ; 4: 3914, 2014 Jan 28.
Artigo em Inglês | MEDLINE | ID: mdl-24468857

RESUMO

Heterojunctions near infrared (NIR) photodetectors have attracted increasing research interests for their wide-ranging applications in many areas such as military surveillance, target detection, and light vision. A high-performance NIR light photodetector was fabricated by coating the methyl-group terminated Si nanowire array with plasmonic gold nanoparticles (AuNPs) decorated graphene film. Theoretical simulation based on finite element method (FEM) reveals that the AuNPs@graphene/CH3-SiNWs array device is capable of trapping the incident NIR light into the SiNWs array through SPP excitation and coupling in the AuNPs decorated graphene layer. What is more, the coupling and trapping of freely propagating plane waves from free space into the nanostructures, and surface passivation contribute to the high on-off ratio as well.

12.
ACS Appl Mater Interfaces ; 5(19): 9362-6, 2013 Oct 09.
Artigo em Inglês | MEDLINE | ID: mdl-24040753

RESUMO

We report on the simple fabrication of monolayer graphene (MLG)/germanium (Ge) heterojunction for infrared (IR) light sensing. It is found that the as-fabricated Schottky junction detector exhibits obvious photovoltaic characteristics, and is sensitive to IR light with high Ilight/Idark ratio of 2 × 10(4) at zero bias voltage. The responsivity and detectivity are as high as 51.8 mA W(-1) and 1.38 × 10(10) cm Hz(1/2) W(-1), respectively. Further photoresponse study reveals that the photovoltaic IR detector displays excellent spectral selectivity with peak sensitivity at 1400 nm, and a fast light response speed of microsecond rise/fall time with good reproducibility and long-term stability. The generality of the above results suggests that the present MLG/Ge IR photodetector would have great potential for future optoelectronic device applications.


Assuntos
Germânio/química , Grafite/química , Desenho de Equipamento , Raios Infravermelhos , Luz , Semicondutores , Silício/química
13.
Nanotechnology ; 24(35): 355203, 2013 Sep 06.
Artigo em Inglês | MEDLINE | ID: mdl-23924708

RESUMO

Here we demonstrate a room temperature processed nonvolatile memory device based on an Al/AlO(x)/CdTe:Sb nanowire (NW) heterojunction. Electrical analysis shows an echelon hysteresis composed of a high-resistance state (HRS) and a low-resistance state (LRS), which can allow it to write and erase data from the device. The conductance ratio is as high as 106, with a retention time of 3 × 104 s. Moreover, the SET voltages ranged from +6 to +8 V, whilst the RESET voltage ∼0 V. In addition, flexible memory nano-devices on PET substrate with comparable switching performance at bending condition were fabricated. XPS analysis of the Al/AlO(x)/CdTe:Sb NW heterojunction after controlled Ar⁺ bombardment reveals that this memory behavior is associated with the presence of ultra-thin AlO(x) film. This Al/AlO(x)/CdTe:Sb NW heterojunction will open up opportunities for new memory devices with different configurations.

14.
Food Chem Toxicol ; 60: 424-30, 2013 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-23939040

RESUMO

Piperine, an alkaloid from black and long peppers (Piper nigrum Linn & Piper longum Linn), has been reported to exhibit antitumor activities in vitro and in vivo. To further understand the antitumor mechanism of piperine, we investigated the growth inhibitory effects of piperine on human prostate cancer DU145, PC-3 and LNCaP cells. Piperine treatment resulted in a dose-dependent inhibition of the proliferation of these cell lines. Cell cycle arrest at G0/G1 was induced and cyclin D1 and cyclin A were downregulated upon piperine treatment. Notably, the level of p21(Cip1) and p27(Kip1) was increased dose-dependently by piperine treatment in both LNCaP and DU145 but not in PC-3 cells, in line with more robust cell cycle arrest in the former two cell lines than the latter one. Although piperine induced low levels of apoptosis, it promoted autophagy as evidenced by the increased level of LC3B-II and the formation of LC3B puncta in LNCaP and PC-3 cells. The piperine-induced autophagic flux was further confirmed by assaying LC3-II accumulation and LC3B puncta formation in the presence of chloroquine, a well-known autophagy inhibitor. Taken together, these results indicated that piperine exhibited anti-proliferative effect in human prostate cancer cells by inducing cell cycle arrest and autophagy.


Assuntos
Alcaloides/toxicidade , Autofagia/efeitos dos fármacos , Benzodioxóis/toxicidade , Pontos de Checagem do Ciclo Celular/efeitos dos fármacos , Proliferação de Células/efeitos dos fármacos , Piperidinas/toxicidade , Alcamidas Poli-Insaturadas/toxicidade , Neoplasias da Próstata/patologia , Linhagem Celular Tumoral , Sobrevivência Celular/efeitos dos fármacos , Ciclina A1/genética , Ciclina A1/metabolismo , Ciclina D1/genética , Ciclina D1/metabolismo , Inibidor de Quinase Dependente de Ciclina p21/genética , Inibidor de Quinase Dependente de Ciclina p21/metabolismo , Inibidor de Quinase Dependente de Ciclina p27/genética , Inibidor de Quinase Dependente de Ciclina p27/metabolismo , Relação Dose-Resposta a Droga , Regulação para Baixo , Fase G1/efeitos dos fármacos , Humanos , Masculino , Neoplasias da Próstata/metabolismo , Regulação para Cima
15.
Small ; 9(17): 2872-9, 2013 Sep 09.
Artigo em Inglês | MEDLINE | ID: mdl-23495044

RESUMO

A new Schottky junction ultraviolet photodetector (UVPD) is fabricated by coating a free-standing ZnO nanorod (ZnONR) array with a layer of transparent monolayer graphene (MLG) film. The single-crystalline [0001]-oriented ZnONR array has a length of about 8-11 µm, and a diameter of 100∼600 nm. Finite element method (FEM) simulation results show that this novel nanostructure array/MLG heterojunction can trap UV photons effectively within the ZnONRs. By studying the I-V characteristics in the temperature range of 80-300 K, the barrier heights of the MLG film/ZnONR array Schottky barrier are estimated at different temperatures. Interestingly, the heterojunction diode with typical rectifying characteristics exhibits a high sensitivity to UV light illumination and a quick response of millisecond rise time/fall times with excellent reproducibility, whereas it is weakly sensitive to visible light irradiation. It is also observed that this UV photodetector (PD) is capable of monitoring a fast switching light with a frequency as high as 2250 Hz. The generality of the above results suggest that this MLG film/ZnONR array Schottky junction UVPD will have potential application in future optoelectronic devices.


Assuntos
Grafite/química , Nanoestruturas/química , Nanotecnologia/métodos , Nanotubos/economia , Raios Ultravioleta , Óxido de Zinco/química
16.
Autophagy ; 9(1): 20-32, 2013 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-23075929

RESUMO

Autophagic responses to chemotherapeutic agents may vary greatly among different prostate cancer cells and have not been well characterized. In this study, we showed that valproic acid (VPA) induced conversion of LC3-I to LC3-II and formation of LC3 puncta, the typical markers of autophagy, in LNCaP and PC-3 cells. However, these markers were undetectable in DU145 cells upon autophagic stimulation, indicating a defect of autophagy in this cell line. Among several critical autophagy-related proteins, ATG5 and ATG12-ATG5 conjugates, which are essential for autophagy induction, were absent in DU145 cells. No canonical transcripts for full-length ATG5 but only two alternatively spliced ATG5 transcripts were identified in DU145 cells. These alternative transcripts lack one or two exons, leading to premature termination of ATG5 translation. Transfection of the wild-type ATG5 gene into DU145 cells rescued the production of ATG5 and ATG12-ATG5 conjugates, resulting in formation of LC3-II conjugates and LC3 puncta. Moreover, the levels of the SQSTM1 protein, which should be degradable as an autophagy adaptor, were much higher in DU145 than in LNCaP and PC-3 cells, but were significantly decreased after ATG5 restoration in DU145 cells. However, expression of wild-type ATG5 in DU145 or knockdown of ATG5 in LNCaP and PC-3 cells did not change the inhibitory effects of VPA on these cells. Collectively, these results indicated that VPA-induced autophagy in prostate cancer cells depended on ATG5 and more importantly, that the autophagy pathway was genetically impaired in DU145 cells, suggesting caution in interpreting autophagic responses in this cell line.


Assuntos
Processamento Alternativo , Autofagia/genética , Autofagia/fisiologia , Proteínas Associadas aos Microtúbulos/genética , Proteínas Associadas aos Microtúbulos/metabolismo , Neoplasias da Próstata/genética , Neoplasias da Próstata/metabolismo , Proteínas Adaptadoras de Transdução de Sinal/metabolismo , Processamento Alternativo/efeitos dos fármacos , Autofagia/efeitos dos fármacos , Proteína 12 Relacionada à Autofagia , Proteína 5 Relacionada à Autofagia , Sequência de Bases , Linhagem Celular Tumoral , Técnicas de Silenciamento de Genes , Humanos , Masculino , Proteínas Associadas aos Microtúbulos/antagonistas & inibidores , Neoplasias da Próstata/tratamento farmacológico , Neoplasias da Próstata/patologia , RNA Neoplásico/genética , RNA Neoplásico/metabolismo , Proteína Sequestossoma-1 , Proteínas Modificadoras Pequenas Relacionadas à Ubiquitina/metabolismo , Transfecção , Ácido Valproico/farmacologia
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