Your browser doesn't support javascript.
loading
Mostrar: 20 | 50 | 100
Resultados 1 - 20 de 28
Filtrar
1.
Artículo en Inglés | MEDLINE | ID: mdl-38710643

RESUMEN

BACKGROUND: Atopic dermatitis (AD) is a chronic inflammatory skin disorder affecting up to 20% of children in developed countries. Although probiotics have shown promise as adjuvant treatments for AD, their mechanisms are not well understood. OBJECTIVE: Building upon our previous studies, we investigated whether Lactobacillus gasseri and its moonlighting glyceraldehyde 3-phosphate dehydrogenase (GAPDH), namely LGp40, could be beneficial in AD management. METHODS: In AD mouse models (SKH and C57BL/6J mice) with ovalbumin (OVA) and Dermatophagoides pteronyssinus (Der p) allergens, aligning with the "outside-in" and "inside-out" hypotheses, we administered L. gasseri orally and LGp40 intraperitoneally to investigate their protective effects. The evaluation involved measuring physiological, pathological, and immune function parameters. To delve deeper into the detailed mechanism of LGp40 protection in AD, additional assays were conducted using human skin keratinocytes (HaCaT) and monocytes (THP1) cell lines. RESULTS: L. gasseri and LGp40 enhanced skin barrier function and increased skin moisture retention. They also led to reduced infiltration of Langerhans cells in the dermis and mitigated skewed Th2 and Th17 immune responses. Moreover, LGp40 inhibited allergen-induced keratinocyte apoptosis through the blockade of the caspase-3 cascade and reduced the NLR family pyrin domain containing 3 (NLRP3) inflammasome in macrophages. These inhibitions were achieved through the activation of the peroxisome proliferator-activated receptor gamma (PPARγ) pathway. CONCLUSION: The results of this study provide a novel insight into the mechanism of action of probiotics in the prevention and treatment for allergic disorders through the moonlighting GAPDH protein.

2.
Small ; 16(45): e2003944, 2020 Nov.
Artículo en Inglés | MEDLINE | ID: mdl-33079462

RESUMEN

Nanoscrolls are a class of nanostructures where atomic layers of 2D materials are stacked consecutively in a coaxial manner to form a 1D spiral topography. Self-assembly of chemical vapor deposition grown 2D WS2 monolayer into quasi-1D van der Waals scroll structure instigates a plethora of unique physiochemical properties significantly different from its 2D counterparts. The physical properties of such nanoscrolls can be greatly manipulated upon hybridizing them with high-quantum-yield colloidal quantum dots, forming 0D/2D structures. The efficient dissociation of excitons at the heterojunctions of QD/2D hybridized nanoscrolls exhibits a 3000-fold increased photosensitivity compared to the pristine 2D-material-based nanoscroll. The synergistic effects of confined geometry and efficient QD scatterers produce a nanocavity with multiple feedback loops, resulting in coherent lasing action with an unprecedentedly low lasing threshold. Predominant localization of the excitons along the circumference of this helical scroll results in a 12-fold brighter emission for the parallel-polarized transition compared to the perpendicular one, as confirmed by finite-difference time-domain simulation. The versatility of hybridized nanoscrolls and their unique properties opens up a powerful route for not-yet-realized devices toward practical applications.

3.
Opt Express ; 28(9): 13542-13552, 2020 Apr 27.
Artículo en Inglés | MEDLINE | ID: mdl-32403826

RESUMEN

Optical memories are vitally important for the future development of high speed and low cost information technologies. Current optical memory devices still suffer from difficulties such as scaling-down of size, short-life expectancy, and non-volatility without the control of a gate electrode. To resolve these obstacles, a robust photoelectronic memory device is designed and demonstrated based on the integration of amorphous InGaZnO (a-IGZO), GNSs, and nitride multiple-quantum-wells light-emitting diode (MQWs LED). Utilizing the inherent nature of the band alignment between a-IGZO and graphene nanosheets (GNSs), electrons can transfer from a-IGZO to GNSs causing a persistent photoconductivity (PPC). With the long-lasting lifetime of PPC, the signal can be written optically and the encoded signal can be read both electrically and optically. The read and write processes reveal little current degradation for more than 10,000 sec, even repeated for more than hundred times. The device can convert invisible information to visible signal, and the encoded information can be simply erased under a reversed bias without a gate electrode. In addition, the memory device possesses a simple vertically stacked structure for 3D integration, and it is compatible with established technologies.

4.
ACS Appl Mater Interfaces ; 16(31): 40611-40627, 2024 Aug 07.
Artículo en Inglés | MEDLINE | ID: mdl-39046148

RESUMEN

Here we demonstrate that cancer metastasis could be modulated by the judicious tuning of physical parameters such as photothermal temperature in nanoparticle-mediated photothermal therapy (PTT). This is supported by theranostic nanosystem design and characterization, in vitro and in vivo analyses, and transcriptome-based gene profiling. In this work, the highly efficient near-infrared II (NIR-II) photoacoustic image (PA)-guided PTT are selectively activated using our developed matrix metalloproteinase (MMP)-triggered in situ assembly of gold nanodandelions (GNDs@gelatin). Unlike other "always-on" NIR PTT agents lacking specific bioactivation and suffering from the intrinsic nonspecific pseudosignals and treatment-related side effects such as metastasis, our GNDs@gelatin possesses important advantages while deployed in cancer PTT that include the following: (1) The theranostic effects could be "turned on" only after specific MMP-2/-9 activity and with acidity in the tumor microenvironment. (2) The quantitative PA diagnosis allows for precise PTT planning for better cancer treatment. (3) GNDs@gelatin could noninvasively quantify MMP activity and efficiently harness NIR-I (808 nm) and NIR-II (1064 nm) energies for tumor ablation. (4) The multibranched nanostructures reabsorb scattered laser photons, thus enhancing the surface plasmons for the pronounced photothermal conversion of aggregated GNDs@gelatin in situ. (5) It is noteworthy that in situ tumor eradication at higher PTT temperature (>55 °C) mediated by GNDs@gelatin could induce subsequent metastasis, which could be otherwise abolished at lower PTT temperatures (50 °C > T > 43 °C). (6) Furthermore, the gene profiling using transcriptome-based microarray including GO and KEGG analyses revealed that 315 differentially expressed genes were identified in higher PTT temperature treated tumors compared with lower PTT temperature ones. These were enriched into some well-known cancer-related pathways, such as cell migration pathway, signal transductions, cell proliferation, wound healing, PPAR signaling, and metabolic pathways. These observations suggest a new perspective of "moderate-is-better" in nanoparticle-mediated PTT for maximizing its therapeutic/prognosis benefits and translational potential with metastasis inhibition.


Asunto(s)
Oro , Rayos Infrarrojos , Técnicas Fotoacústicas , Terapia Fototérmica , Nanomedicina Teranóstica , Animales , Ratones , Oro/química , Humanos , Línea Celular Tumoral , Metástasis de la Neoplasia , Femenino , Ratones Endogámicos BALB C , Nanopartículas del Metal/química , Ratones Desnudos , Metaloproteinasa 2 de la Matriz/metabolismo , Gelatina/química , Neoplasias/patología , Neoplasias/terapia , Neoplasias/diagnóstico por imagen
5.
Int J Nanomedicine ; 18: 4253-4274, 2023.
Artículo en Inglés | MEDLINE | ID: mdl-37534057

RESUMEN

Background: Cancer multidrug resistance (MDR) is an important factor that severely affects the chemotherapeutic efficacy. Among various methods to bypass MDR, usage of cytokines, such as tumor necrosis factor alpha (TNFα) is attractive, which exerts antitumor effects of immunotherapeutic response and apoptotic/proinflammatory pathways. Nevertheless, the challenges remain how to implement targeted delivery of TNFα to reduce toxicity and manifest the involved signaling mechanism that subdues MDR. Methods: We synthesized a multifunctional nanosytem, in which TNFα covalently bound to doxorubicin (Dox)-loaded pH-responsive mesoporous silica nanoparticles (MSN) through bi-functional polyethylene glycol (TNFα-PEG-MSN-Hydrazone-Dox) as a robust design to overcome MDR. Results: The salient features of this nanoplatform are: 1) by judicious tailoring of TNFα concentration conjugated on MSN, we observed it could lead to a contrary effect of either proliferation or suppression of tumor growth; 2) the MSN-TNFα at higher concentration serves multiple functions, besides tumor targeting and inducer of apoptosis through extrinsic pathway, it inhibits the expression level of p-glycoprotein (P-gp), a cell membrane protein that functions as a drug efflux pump; 3) the enormous surface area of MSN provides for TNFα functionalization, and the nanochannels accommodate chemotherapeutics, Dox; 4) targeted intracellular release of Dox through the pH-dependent cleavage of hydrazone bonds induces apoptosis by the specific intrinsic pathway; and 5) TNFα-PEG-MSN-Hydrazone-Dox (MSN-Dox-TNFα) could infiltrate deep into the 3D spheroid tumor model through disintegration of tight junction proteins. When administered intratumorally in a Dox-resistant mouse tumor model, MSN-Dox-TNFα exhibited a synergistic therapeutic effect through the collective performances of TNFα and Dox. Conclusion: We hereby develop and demonstrate a multifunctional MSN-Dox-TNFα system with concentration-tailored TNFα that can abrogate the drug resistance mechanism, and significantly inhibit the tumor growth through both intrinsic and extrinsic apoptosis pathways, thus making it a highly potential nanomedicine translated in the treatment of MDR tumors.


Asunto(s)
Nanopartículas , Neoplasias , Ratones , Animales , Citocinas , Factor de Necrosis Tumoral alfa , Neoplasias/tratamiento farmacológico , Neoplasias/patología , Doxorrubicina , Apoptosis , Resistencia a Múltiples Medicamentos , Nanopartículas/química , Proliferación Celular , Hidrazonas/farmacología , Hidrazonas/uso terapéutico , Dióxido de Silicio/química , Resistencia a Antineoplásicos , Porosidad
6.
Nanomaterials (Basel) ; 13(11)2023 Jun 02.
Artículo en Inglés | MEDLINE | ID: mdl-37299694

RESUMEN

Although radiotherapy is one of the most important curative treatments for cancer, its clinical application is associated with undesired therapeutic effects on normal or healthy tissues. The use of targeted agents that can simultaneously achieve therapeutic and imaging functions could constitute a potential solution. Herein, we developed 2-deoxy-d-glucose (2DG)-labeled poly(ethylene glycol) (PEG) gold nanodots (2DG-PEG-AuD) as a tumor-targeted computed tomography (CT) contrast agent and radiosensitizer. The key advantages of the design are its biocompatibility and targeted AuD with excellent sensitivity in tumor detection via avid glucose metabolism. As a consequence, CT imaging with enhanced sensitivity and remarkable radiotherapeutic efficacy could be attained. Our synthesized AuD displayed linear enhancement of CT contrast as a function of its concentration. In addition, 2DG-PEG-AuD successfully demonstrated significant augmentation of CT contrast in both in vitro cell studies and in vivo tumor-bearing mouse models. In tumor-bearing mice, 2DG-PEG-AuD showed excellent radiosensitizing functions after intravenous injection. Results from this work indicate that 2DG-PEG-AuD could greatly potentiate theranostic capabilities by providing high-resolution anatomical and functional images in a single CT scan and therapeutic capability.

7.
ACS Appl Mater Interfaces ; 15(15): 19121-19128, 2023 Apr 19.
Artículo en Inglés | MEDLINE | ID: mdl-37027524

RESUMEN

The assorted utilization of infrared detectors induces the demand for more comprehensive and high-performance electronic devices that work at room temperature. The intricacy of the fabrication process with bulk material limits the exploration in this field. However, two-dimensional (2D) materials with a narrow band gap opening aid in infrared (IR) detection relatively, but the photodetection range is narrowed due to the inherent band gap. In this study, we report an unprecedented attempt at the coordinated use of both 2D heterostructure (InSe/WSe2) and the dielectric polymer (poly(vinylidene fluoride-trifluoroethylene), P(VDF-TrFE)) for both visible and IR photodetection in a single device. The remnant polarization due to the ferroelectric effect of the polymer dielectric enhances the photocarrier separation in the visible range, resulting in high photoresponsivity. On the other hand, the pyroelectric effect of the polymer dielectric causes a change in the device current due to the increased temperature induced by the localized heating effect of the IR irradiation, which results in the change of ferroelectric polarization and induces the redistribution of charge carriers. In turn, it changes the built-in electric field, the depletion width, and the band alignment across the p-n heterojunction interface. Consequently, the charge carrier separation and the photosensitivity are therefore enhanced. Through the coupling between pyroelectricity and built-in electric field across the heterojunction, the specific detectivity for the photon energy below the band gap of the constituent 2D materials can reach up to 1011 Jones, which is better than all reported pyroelectric IR detectors. The proposed approach combining the ferroelectric and pyroelectric effects of the dielectric as well as exceptional properties of the 2D heterostructures can spark the design of advanced and not-yet realized optoelectronic devices.

8.
Carcinogenesis ; 33(1): 209-19, 2012 Jan.
Artículo en Inglés | MEDLINE | ID: mdl-22021908

RESUMEN

Hepatitis B virus X antigen plays an important role in the development of human hepatocellular carcinoma (HCC). The key regulators controlling the temporal downstream gene expression for HCC progression remains unknown. In this study, we took advantage of systems biology approach and analyzed the microarray data of the HBx transgenic mouse as a screening process to identify the differentially expressed genes and applied the software Pathway Studio to identify potential pathways and regulators involved in HCC. Using subnetwork enrichment analysis, we identified five common regulator genes: EDN1, BMP7, BMP4, SPIB and SRC. Upregulation of the common regulators was validated in the other independent HBx transgenic mouse lines. Furthermore, we verified the correlation of their RNA expression levels by using the human HCC samples, and their protein levels by using the human liver disease tissue arrays. EDN1, bone morphogenetic protein (BMP) 4 and BMP7 were upregulated in cirrhosis, BMP4, BMP7 and SRC were further upregulated in hepatocellular or cholangiocellular carcinoma samples. The trend of increasing expression of the common regulators correlates well with the progression of human liver cancer. Overexpression of the common regulators increases the cell viability, promotes migration and invasiveness and enhances the colony formation ability in Hep3B cells. Our approach allows us to identify the critical genes in hepatocarcinogenesis in an HBx-induced mouse model. The validation of the gene expressions in the liver cancer of human patients and their cellular function assays suggests that the identified common regulators may serve as useful molecular targets for the early-stage diagnosis or therapy for HCC.


Asunto(s)
Neoplasias Hepáticas Experimentales/etiología , Transactivadores/fisiología , Animales , Proteína Morfogenética Ósea 4/genética , Proteína Morfogenética Ósea 7/genética , Proteínas de Unión al ADN/genética , Modelos Animales de Enfermedad , Humanos , Neoplasias Hepáticas Experimentales/patología , Masculino , Ratones , Ratones Endogámicos C57BL , Ratones Transgénicos , Estadificación de Neoplasias , Análisis de Secuencia por Matrices de Oligonucleótidos , Transactivadores/genética , Proteínas Reguladoras y Accesorias Virales , Familia-src Quinasas/genética
9.
Birth Defects Res C Embryo Today ; 93(2): 157-72, 2011 Jun.
Artículo en Inglés | MEDLINE | ID: mdl-21671355

RESUMEN

Liver is the largest organ in the human body, and it regulates many physiological processes. Many studies on liver development in different model organisms have demonstrated that the mechanism of hepatogenesis is conserved in vertebrates. The identification of the genes and regulatory pathways involved in liver formation provides a basis for the diagnosis of liver diseases and therapeutic interventions. Hepatocellular carcinoma is the third leading cause of mortality worldwide. In the last decade, genetic alterations, which include the gain and loss of DNA, as well as mutations and epigenomic changes, have been identified as important factors in liver cancer. Many genetic pathways are dysregulated during carcinogenesis. Here, we review the gene regulatory networks that underlie liver organogenesis and the dysregulation of these pathways in liver cancer. The genes and pathways involved in hepatogenesis and liver cancer are largely conserved between zebrafish and humans, making this an ideal model organism for the study of this disease. A better understanding of liver development may aid in the development of new diagnostic and therapeutic approaches to liver cancer.


Asunto(s)
Carcinoma Hepatocelular/genética , Regulación Neoplásica de la Expresión Génica/genética , Redes Reguladoras de Genes/genética , Neoplasias Hepáticas/genética , Hígado/embriología , Modelos Animales , Morfogénesis/genética , Pez Cebra , Animales , Ancirinas/genética , Carcinoma Hepatocelular/fisiopatología , Inhibidor p16 de la Quinasa Dependiente de Ciclina/genética , Regulación Neoplásica de la Expresión Génica/fisiología , Redes Reguladoras de Genes/fisiología , Neoplasias Hepáticas/fisiopatología , Morfogénesis/fisiología , Mutación/genética , Proteína de Retinoblastoma/genética , Transducción de Señal/genética , Transducción de Señal/fisiología , Transactivadores/genética , Proteína p53 Supresora de Tumor/genética , Proteínas Reguladoras y Accesorias Virales , Proteínas Wnt/metabolismo , beta Catenina/metabolismo
10.
ACS Nano ; 15(5): 8686-8693, 2021 May 25.
Artículo en Inglés | MEDLINE | ID: mdl-33970616

RESUMEN

Multistate logic is recognized as a promising approach to increase the device density of microelectronics, but current approaches are offset by limited performance and large circuit complexity. We here demonstrate a route toward increased integration density that is enabled by a mechanically tunable device concept. Bi-anti-ambipolar transistors (bi-AATs) exhibit two distinct peaks in their transconductance and can be realized by a single 2D-material heterojunction-based solid-state device. Dynamic deformation of the device reveals the co-occurrence of two conduction pathways to be the origin of this previously unobserved behavior. Initially, carrier conduction proceeds through the junction edge, but illumination and application of strain can increase the recombination rate in the junction sufficiently to support an alternative carrier conduction path through the junction area. Optical characterization reveals a tunable emission pattern and increased optoelectronic responsivity that corroborates our model. Strain control permits the optimization of the conduction efficiency through both pathways and can be employed in quaternary inverters for future multilogic applications.

11.
J Virol ; 83(13): 6464-76, 2009 Jul.
Artículo en Inglés | MEDLINE | ID: mdl-19369327

RESUMEN

Vaccinia virus A26 protein is an envelope protein of the intracellular mature virus (IMV) of vaccinia virus. A mutant A26 protein with a truncation of the 74 C-terminal amino acids was expressed in infected cells but failed to be incorporated into IMV (W. L. Chiu, C. L. Lin, M. H. Yang, D. L. Tzou, and W. Chang, J. Virol 81:2149-2157, 2007). Here, we demonstrate that A27 protein formed a protein complex with the full-length form but not with the truncated form of A26 protein in infected cells as well as in IMV. The formation of the A26-A27 protein complex occurred prior to virion assembly and did not require another A27-binding protein, A17 protein, in the infected cells. A26 protein contains six cysteine residues, and in vitro mutagenesis showed that Cys441 and Cys442 mediated intermolecular disulfide bonds with Cys71 and Cys72 of viral A27 protein, whereas Cys43 and Cys342 mediated intramolecular disulfide bonds. A26 and A27 proteins formed disulfide-linked complexes in transfected 293T cells, showing that the intermolecular disulfide bond formation did not depend on viral redox pathways. Finally, using cell fusion from within and fusion from without, we demonstrate that cell surface glycosaminoglycan is important for virus-cell fusion and that A26 protein, by forming complexes with A27 protein, partially suppresses fusion.


Asunto(s)
Proteínas Portadoras/metabolismo , Fusión Celular , Disulfuros/metabolismo , Glicosaminoglicanos/metabolismo , Virus Vaccinia/metabolismo , Proteínas Virales de Fusión/metabolismo , Línea Celular , Cisteína/metabolismo , Humanos , Proteínas de la Membrana , Mutagénesis Sitio-Dirigida , Unión Proteica
12.
RSC Adv ; 10(30): 17787-17794, 2020 May 05.
Artículo en Inglés | MEDLINE | ID: mdl-35515600

RESUMEN

We have studied the reforming reaction of ethanol co-adsorbed with atomic oxygen (O*, * denotes adspecies) and deuterated water (D2O*) on a Rh(111) surface, with varied surface probe techniques under UHV conditions and with density-functional-theory calculations. Adsorbed ethanol molecules were found to penetrate readily through pre-adsorbed water, even up to eight overlayers, to react at the Rh surface; they decomposed at a probability promoted by the water overlayers. The production probabilities of H2, CO, CH2CH2 and CH4 continued to increase with co-adsorbed D2O*, up to two D2O overlayers, despite separate increasing rates; above two D2O overlayers, those of H2, CO and CH2CH2 were approximately saturated while that of CH4 decreased. The increased (or saturated) production probabilities are rationalized with an increased (saturated) concentration of surface hydroxyl (OD*, formed by O* abstracting D from D2O*), whose intermolecular hydrogen bonding with adsorbed ethanol facilitates proton transfer from ethanol to OD* and thus enhances the reaction probability. The decreasing behavior of CH4 could also involve the competition for H* with the formation of H2 and HDO.

13.
Theranostics ; 10(15): 6758-6773, 2020.
Artículo en Inglés | MEDLINE | ID: mdl-32550902

RESUMEN

Photodynamic therapy (PDT), which involves the generation of reactive oxygen species (ROS) through interactions of a photosensitizer (PS) with light and oxygen, has been applied in oncology. Over the years, PDT techniques have been developed for the treatment of deep-seated cancers. However, (1) the tissue penetration limitation of excitation photon, (2) suppressed efficiency of PS due to multiple energy transfers, and (3) insufficient oxygen source in hypoxic tumor microenvironment still constitute major challenges facing the clinical application of PDT for achieving effective treatment. We present herein a PS-independent, ionizing radiation-induced PDT agent composed of yttrium oxide nanoscintillators core and silica shell (Y2O3:Eu@SiO2) with an annealing process. Our results revealed that annealed Y2O3:Eu@SiO2 could directly induce comprehensive photodynamic effects under X-ray irradiation without the presence of PS molecules. The crystallinity of Y2O3:Eu@SiO2 was demonstrated to enable the generation of electron-hole (e--h+) pairs in Y2O3 under ionizing irradiation, giving rise to the formation of ROS including superoxide, hydroxyl radical and singlet oxygen. In particular, combining Y2O3:Eu@SiO2 with fractionated radiation therapy increased radio-resistant tumor cell damage. Furthermore, photoacoustic imaging of tumors showed re-distribution of oxygen saturation (SO2) and reoxygenation of the hypoxia region. The results of this study support applicability of the integration of fractionated radiation therapy with Y2O3:Eu@SiO2, achieving synchronously in-depth and oxygen-insensitive X-ray PDT. Furthermore, we demonstrate Y2O3:Eu@SiO2 exhibited radioluminescence (RL) under X-ray irradiation and observed the virtually linear correlation between X-ray-induced radioluminescence (X-RL) and the Y2O3:Eu@SiO2 concentration in vivo. With the pronounced X-RL for in-vivo imaging and dosimetry, it possesses significant potential for utilization as a precision theranostics producing highly efficient X-ray PDT for deep-seated tumors.


Asunto(s)
Nanopartículas/química , Nanotecnología/instrumentación , Neoplasias Ováricas/terapia , Fotoquimioterapia/instrumentación , Dióxido de Silicio/química , Itrio/química , Animales , Línea Celular Tumoral , Femenino , Ratones , Ratones Desnudos , Nanopartículas/efectos de la radiación , Neoplasias Ováricas/patología , Fotoquimioterapia/métodos , Fármacos Fotosensibilizantes/administración & dosificación , Oxígeno Singlete , Nanomedicina Teranóstica , Rayos X , Ensayos Antitumor por Modelo de Xenoinjerto
14.
ACS Appl Mater Interfaces ; 12(43): 49122-49129, 2020 Oct 28.
Artículo en Inglés | MEDLINE | ID: mdl-33058666

RESUMEN

With the superiority of laser-level intensity, narrow spectral line width, and broad-angular emission, random lasers (RLs) have drawn considerable research interests for their potential to carry out a variety of applications. In this work, the applications associated with optical-encoded technologies, including security printing, military friend or foe identification (FFI), and anticounterfeiting of documents are highlighted, and the concept of a transient RL "smart ink" has been proposed. The proof-of-concept was demonstrated as invisible signatures, which encoded the messages through the spectral difference of spontaneous emission and RL under specified conditions. Next, the possibility of encoding the data with multibit signals was further confirmed by exploiting the threshold tunability of RLs. Moreover, the transient characteristic of this smart ink and its capability to be attached on freeform surfaces of different materials were also shown. With the advantages of a facile manufacturing process and multiple purposes, it is expected that this ink can soon be carried out in a variety of practical utilities.

15.
ACS Appl Mater Interfaces ; 12(23): 26213-26221, 2020 Jun 10.
Artículo en Inglés | MEDLINE | ID: mdl-32400164

RESUMEN

Tuning the optical and electrical properties by stacking different layers of two-dimensional (2D) materials enables us to create unusual physical phenomena. Here, we demonstrate an alternative approach to enhance charge separation and alter physical properties in van der Waals heterojunctions with type-II band alignment by using thin dielectric spacers. To illustrate our working principle, we implement a hexagonal boron nitride (h-BN) sieve layer in between an InSe/GeS heterojunction. The optical transitions at the junctions studied by photoluminescence and the ultrafast pump-probe technique show quenching of emission without h-BN layers exhibiting an indirect recombination process. This quenching effect due to strong interlayer coupling was confirmed with Raman spectroscopic studies. In contrast, h-BN layers in between InSe and GeS show strong enhancement in emission, giving another degree of freedom to tune the heterojunction property. The two-terminal photoresponse study supports the argument by showing a large photocurrent density for an InSe/h-BN/GeS device by avoiding interlayer charge recombination. The enhanced charge separation with h-BN mediation manifests a photoresponsivity and detectivity of 9 × 102 A W-1 and 3.4 × 1014 Jones, respectively. Moreover, a photogain of 1.7 × 103 shows a high detection of electrons for the incident photons. Interestingly, the photovoltaic short-circuit current is switched from positive to negative, whereas the open-circuit voltage changes from negative to positive. Our proposed enhancement of charge separation with 2D-insulator mediation, therefore, provides a useful route to manipulate the physical properties of heterostructures and for the future development of high-performance optoelectronic devices.

16.
Opt Express ; 17(6): 4342-7, 2009 Mar 16.
Artículo en Inglés | MEDLINE | ID: mdl-19293860

RESUMEN

A new composite consisting of ZnO nanorods decorated with Ag(2)O nanoparticles has been synthesized and characterized. It is found that the band gap emission of ZnO nanorods can be greatly enhanced by about 10 times, while the defect emission can be suppressed to the detection limit, simultaneously. The ratio between the band gap and defect emission reaches to an enhanced factor of about 600 times. The underlying mechanism is attributed to the combined effects of surface modification, band alignment, as well as charge transfer. Our approach provided here can be extended to many other semiconductors for creating nanocomposites with novel optical properties.

17.
Biomater Sci ; 7(11): 4720-4729, 2019 Nov 01.
Artículo en Inglés | MEDLINE | ID: mdl-31495835

RESUMEN

Herein, we report a new type of biodegradable, high surface-area gold nanodandelions (GNDs). This report possesses important features and some are the first of its kind: (1) the large scale green synthesis of GNDs with high monodispersity and a circa 100% yield with consistent chemistry, manufacturing and controls (CMC); (2) cellular/physiological degradability of GNDs leading to its disassembly into debris, which is indicative of the potential for possible body clearance; (3) precision control of the chemicophysical properties of the GNDs including shape, petal number and size, all can be judiciously fine-tuned by the synthetic parameters; (4) highly efficient radiotheranostics of GNDs encompassing better enhanced computed tomography (CT) contrast and pronounced X-ray induced reactive oxygen species (ROS) generation than conventional spherical gold nanoparticles (AuNP). It is noteworthy that the GNDs demonstrate a unique combinational effect of radiosensitization (production of superoxide anions and hydroxyl radicals) and type II photodynamic interaction (generation of singlet oxygen). Given the above, our reported GNDs are promising in clinical translation as radiotheranostics.


Asunto(s)
Antineoplásicos/farmacología , Oro/farmacología , Nanopartículas del Metal/química , Radiofármacos/farmacología , Nanomedicina Teranóstica , Animales , Antineoplásicos/química , Antineoplásicos/metabolismo , Proliferación Celular/efectos de los fármacos , Ensayos de Selección de Medicamentos Antitumorales , Femenino , Oro/química , Oro/metabolismo , Humanos , Ratones , Ratones Desnudos , Neoplasias Experimentales/tratamiento farmacológico , Neoplasias Experimentales/metabolismo , Tamaño de la Partícula , Radiofármacos/química , Radiofármacos/metabolismo , Especies Reactivas de Oxígeno/análisis , Especies Reactivas de Oxígeno/metabolismo , Propiedades de Superficie , Células Tumorales Cultivadas
18.
ACS Appl Mater Interfaces ; 11(27): 24269-24278, 2019 Jul 10.
Artículo en Inglés | MEDLINE | ID: mdl-31250634

RESUMEN

Two-dimensional ternary materials are attracting widespread interest because of the additional degree of freedom available to tailor the material property for a specific application. An In1-xSnxSe phototransistor possessing tunable ultrahigh mobility by Sn-doping engineering is demonstrated in this study. A striking feature of In1-xSnxSe flakes is the reduction in the oxide phase compared to undoped InSe, which is validated by spectroscopic analyses. Moreover, first-principles density functional calculations performed for the In1-xSnxSe crystal system reveal the same effective mass when doped with Sn atoms. Hence, because of an increased lifetime owing to the enhanced crystal quality, the carriers in In1-xSnxSe have higher mobility than in InSe. The internally boosted electrical properties of In1-xSnxSe exhibit ultrahigh mobility of 2560 ± 240 cm2 V-1 s-1 by suppressing the interfacial traps with substrate modification and channel encapsulation. As a phototransistor, the ultrathin In1-xSnxSe flakes are highly sensitive with a detectivity of 1014 Jones. It possesses a large photoresponsivity and photogain (Vg = 40 V) as high as 3 × 105 A W-1 and 0.5 × 106, respectively. The obtained results outperform all previously reported performances of InSe-based devices. Thus, the doping-engineered In1-xSnxSe-layered semiconductor finds a potential application in optoelectronics and meets the demand for faster electronic technology.

19.
J Nanosci Nanotechnol ; 8(12): 6344-8, 2008 Dec.
Artículo en Inglés | MEDLINE | ID: mdl-19205204

RESUMEN

A new and general approach based on vapor-phase transport technique using Au-coated plant cell walls has been developed to synthesize patterned ZnO nanostructures. Nanowires, nanodendrites and nanotowers were fabricated by adsorption of different metallic ions on plant cell walls. It is shown that plant cell wall can serve as a well-defined template to grow patterned nanostructures. Using transmission electron microscope and Raman spectroscopy, the structural characteristic of the nanostructures were investigated, exhibiting good crystallinity and hexagonal symmetry of the nanomaterials. Quite interestingly, the shape of the nanostructures can be controlled by the metallic ions adsorbed on plant cell walls. Without metallic ions, a homogeneous distribution of nanowires was obtained. On the other hand, with Ni+2 or Fe+3 ions, nanodendrites and nanotowers were observed, respectively. Our approach provides a low cost method that opens up new possibilities for the growth of patterned nanomaterials with desired shapes.


Asunto(s)
Pared Celular/química , Pared Celular/ultraestructura , Nanoestructuras/química , Nanoestructuras/ultraestructura , Óxido de Zinc/química , Adsorción , Euphorbiaceae/química , Euphorbiaceae/ultraestructura , Oro , Nanopartículas del Metal/química , Nanopartículas del Metal/ultraestructura , Microscopía Electrónica de Rastreo , Nanotecnología , Nanocables/química , Nanocables/ultraestructura , Espectrometría Raman
20.
Sci Rep ; 8(1): 2720, 2018 02 09.
Artículo en Inglés | MEDLINE | ID: mdl-29426912

RESUMEN

Random laser with intrinsically uncomplicated fabrication processes, high spectral radiance, angle-free emission, and conformal onto freeform surfaces is in principle ideal for a variety of applications, ranging from lighting to identification systems. In this work, a white random laser (White-RL) with high-purity and high-stability is designed, fabricated, and demonstrated via the cost-effective materials (e.g., organic laser dyes) and simple methods (e.g., all-solution process and self-assembled structures). Notably, the wavelength, linewidth, and intensity of White-RL are nearly isotropic, nevertheless hard to be achieved in any conventional laser systems. Dynamically fine-tuning colour over a broad visible range is also feasible by on-chip integration of three free-standing monochromatic laser films with selective pumping scheme and appropriate colour balance. With these schematics, White-RL shows great potential and high application values in high-brightness illumination, full-field imaging, full-colour displays, visible-colour communications, and medical biosensing.

SELECCIÓN DE REFERENCIAS
DETALLE DE LA BÚSQUEDA