Your browser doesn't support javascript.
loading
Mostrar: 20 | 50 | 100
Resultados 1 - 20 de 34
Filtrar
1.
Biomaterials ; 246: 119997, 2020 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-32247937

RESUMO

Transcription factor complex NF-κB (p65/p50) is localized to the cytoplasm by its inhibitor IκBα. Upon activation, the Rel proteins p65/p50 are released from IκBα and transported through nuclear pore to affect many gene expressions. While inhibitions of up or down stream signal pathways are often ineffective due to crosstalks and compensations, direct blocking of the Rel proteins p65/p50 has long been proposed as a potential target for cancer therapy. In this work, a nanoparticle/antibody complex targeting NF-κB is employed to catch the Rel protein p65 in perinuclear region and thus blocking the translocation near the nuclear pore gate. TAT peptide conjugated on mesoporous silica nanoparticles (MSN) help non-endocytosis cell-membrane transducing and converge toward perinuclear region, where the p65 specific antibody performed the targeting and catching against active NF-κB p65 effectively. The size of the p65 bound nanoparticle becomes too big to enter nucleus. Simultaneous treatment of mice with the hybrid MSN and doxorubicin conferred a significant therapeutic effect against 4T1 tumor-bearing mice. The new approach of anti-body therapy targeting on transcription factor with "nucleus focusing" and "size exclusion blocking" effects of the antibody-conjugated nanoparticle is general and may be applicable to modulating other transcription factors.

2.
ACS Appl Mater Interfaces ; 11(17): 15322-15331, 2019 May 01.
Artigo em Inglês | MEDLINE | ID: mdl-30986029

RESUMO

Reactive oxygen species (ROS)-induced oxidative stress leads to neuron damage and is involved in the pathogenesis of chronic inflammation in neurodegenerative diseases (NDs), such as Alzheimer's, Parkinson's, and amyotrophic lateral sclerosis. Researchers, therefore, are looking for antiinflammatory drugs and gene therapy approaches to slow down or even prevent neurological disorders. Combining therapeutics has shown a synergistic effect in the treatment of human diseases. Many nanocarriers could be designed for the simultaneous codelivery of drugs with genes to fight diseases. However, only a few researches have been performed in NDs. In this study, we developed a mesoporous silica nanoparticle (MSN)-based approach for neurodegenerative therapy. This MSN-based platform involved multiple designs in the targeted codelivery of (1) curcumin, a natural antioxidant product, to protect ROS-induced cell damage and (2) plasmid RhoG-DsRed, which is associated with the formation of lamellipodia and filopodia for promoting neurite outgrowth. At the same time, TAT peptide was introduced to the plasmid RhoG-DsRed via electrostatic interaction to elevate the efficiency of nonendocytic pathways and the nuclear plasmid delivery of RhoG-DsRed in cells for enhanced gene expression. Besides, such a plasmid RhoG-DsRed/TAT complex could work as a noncovalent gatekeeper. The release of curcumin inside the channel of the MSN could be triggered when the complex was dissociated from the MSN surface. Taken together, this MSN-based platform combining genetic and pharmacological manipulations of an actin cytoskeleton as well as oxidative stress provides an attractive way for ND therapy.


Assuntos
Curcumina/farmacologia , Portadores de Fármacos/química , Nanopartículas/química , Crescimento Neuronal/efeitos dos fármacos , Plasmídeos/metabolismo , Dióxido de Silício/química , Citoesqueleto de Actina/efeitos dos fármacos , Animais , Linhagem Celular Tumoral , Curcumina/química , GTP Fosfo-Hidrolases/genética , Camundongos , Estresse Oxidativo , Tamanho da Partícula , Fragmentos de Peptídeos/química , Plasmídeos/química , Porosidade , Espécies Reativas de Oxigênio/metabolismo , Produtos do Gene tat do Vírus da Imunodeficiência Humana/química
3.
ACS Appl Mater Interfaces ; 10(46): 39898-39903, 2018 Nov 21.
Artigo em Inglês | MEDLINE | ID: mdl-30372020

RESUMO

The desire to improve human lives has led to striking development in biosensing technologies. While the ongoing research efforts are mostly dedicated to enhancing speed and sensitivity of the sensor, a third consideration that has become increasingly important is compactness, which is strongly desired in emergency situations and personal health management. Surface plasmon resonance imaging (SPRi) is one of the few techniques that can potentially fulfill all the three goals, considering its multiplexed assay capability. However, miniaturizing SPRi biosensors remains elusive as it entails complicated optical gears. Here, we significantly slim the architecture of SPRi devices by visualizing the varied local density of states around analytes. The unusual detection scheme is realized by building a gain-assisted SPRi with InGaN quantum wells (QWs), where the QW-plasmon coupling efficiency hinges on localized refractive index variation. This new modality abolishes the prism, the polarizer, and the beam-tracking components in the most used Kretschmann configuration without compromising the performances.

4.
Phys Chem Chem Phys ; 20(43): 27245-27255, 2018 Nov 07.
Artigo em Inglês | MEDLINE | ID: mdl-30182107

RESUMO

Super-resolution imaging based on single-molecule localization microscopy combined with the surface plasmon polariton (SPP)-enhanced fluorescence of spontaneously blinking fluorophores was demonstrated to visualize the nanoscale-level positioning information of cell-adhesion-associated proteins. Glass substrates with a deposited silver layer were utilized to induce a SPP-enhanced field on the silver surface and significantly strengthen the fluorescence signals of the fluorophores by more than 300%. The illumination power density for localization imaging at a spatial resolution of 25 ± 11 nm was 31.6 W cm-2. This low illumination power density will facilitate the reduction of phototoxicity of the biospecimens for single-molecule localization imaging. The proposed strategy provides a uniform distribution of the SPP-enhanced field on the silver surface, enabling visualization of the spatial distribution of labeled proteins without interference caused by the enhanced field distribution.

5.
Nanoscale Res Lett ; 13(1): 123, 2018 Apr 24.
Artigo em Inglês | MEDLINE | ID: mdl-29693204

RESUMO

Reactive oxygen species (ROS) have crucial roles in cell signaling and homeostasis. Overproduction of ROS can induce oxidative damage to various biomolecules and cellular structures. Therefore, developing an approach capable of monitoring and quantifying ROS in living cells is significant for physiology and clinical diagnoses. Some cell-permeable fluorogenic probes developed are useful for the detection of ROS while in conjunction with horseradish peroxidase (HRP). Their intracellular scenario is however hindered by the membrane-impermeable property of enzymes. Herein, a new approach for intracellular sensing of ROS by using horseradish peroxidase-encapsulated hollow silica nanospheres (designated HRP@HSNs), with satisfactory catalytic activity, cell membrane permeability, and biocompatibility, was prepared via a microemulsion method.These HRP@HSNs, combined with selective probes or targeting ligands, could be foreseen as ROS-detecting tools in specific organelles or cell types. As such, dihydrorhodamine 123-coupled HRP@HSNs were used for the qualitative and semi-quantitative analysis of physiological H2O2 levels in activated RAW 264.7 macrophages. We envision that this HSNs encapsulating active enzymes can be conjugated with selective probes and targeting ligands to detect ROS in specific organelles or cell types of interest.

6.
J Biomed Opt ; 22(2): 26008, 2017 02 01.
Artigo em Inglês | MEDLINE | ID: mdl-28241274

RESUMO

Wavelength tunable temporal focusing multiphoton excitation microscopy (TFMPEM) is conducted to visualize optical sectioning images of multiple fluorophore­labeled specimens through the optimal two-photon excitation (TPE) of each type of fluorophore. The tunable range of excitation wavelength was determined by the groove density of the grating, the diffraction angle, the focal length of lenses, and the shifting distance of the first lens in the beam expander. Based on a consideration of the trade-off between the tunable-wavelength range and axial resolution of temporal focusing multiphoton excitation imaging, the presented system demonstrated a tunable-wavelength range from 770 to 920 nm using a diffraction grating with groove density of 830 ?? lines / mm . TPE fluorescence imaging examination of a fluorescent thin film indicated that the width of the axial confined excitation was 3.0 ± 0.7 ?? ? m and the shifting distance of the temporal focal plane was less than 0.95 ?? ? m within the presented wavelength tunable range. Fast different wavelength excitation and three-dimensionally rendered imaging of Hela cell mitochondria and cytoskeletons and mouse muscle fibers were demonstrated. Significantly, the proposed system can improve the quality of two-color TFMPEM images through different excitation wavelengths to obtain higher-quality fluorescent signals in multiple-fluorophore measurements.


Assuntos
Microscopia de Fluorescência por Excitação Multifotônica , Imagem Óptica/métodos , Animais , Citoesqueleto/química , Células HeLa , Humanos , Camundongos , Mitocôndrias/química , Fibras Musculares Esqueléticas/química
7.
Nanotechnology ; 27(47): 475101, 2016 Nov 25.
Artigo em Inglês | MEDLINE | ID: mdl-27775920

RESUMO

Flexible polymer nanopillar substrates were used to systematically demonstrate cell alignment and migration guided by the directional formation of focal adhesions. The polymer nanopillar substrates were constructed to various height specifications to provide an extensive variation of flexibility; a rectangular arrangement created spatial confinement between adjacent nanopillars, providing less spacing in the horizontal and vertical directions. Three polymer nanopillar substrates with the diameter of 400 nm and the heights of 400, 800, and 1200 nm were fabricated. Super-resolution localization imaging and protein pair-distance analysis of vinculin proteins revealed that Chinese hamster ovary (CHO) cells formed mature focal adhesions on 1200 nm high nanopillar substrates by bending adjacent nanopillars to link dot-like adhesions. The spacing confinement of the adjacent nanopillars enhanced the orthogonal directionality of the formation tendency of the mature focal adhesions. The directional formation of the mature focal adhesions also facilitated the organization of actin filaments in the horizontal and vertical directions. Moreover, 78% of the CHO cells were aligned in these two directions, in conformity with the flexibility and nanotopographical cues of the nanopillars. Biased cell migration was observed on the 1200 nm high nanopillar substrates.


Assuntos
Movimento Celular , Animais , Células CHO , Adesão Celular , Cricetinae , Cricetulus , Adesões Focais , Polímeros
8.
ACS Appl Mater Interfaces ; 8(28): 17944-54, 2016 Jul 20.
Artigo em Inglês | MEDLINE | ID: mdl-27353012

RESUMO

Reactive oxygen species (ROS) are important factors in many clinical diseases. However, direct delivery of antioxidant enzymes into cells is difficult due to poor cell uptake. A proper design of delivery of enzymes by nanoparticles is very desirable for therapeutic purposes. To overcome the cell barrier problem, a designed mesoporous silica nanoparticle (MSN) system with attached TAT-fusion denatured enzyme for enhancing cell membrane penetration has been developed. Simultaneous delivery of two up-downstream antioxidant enzymes, superoxide dismutase (SOD) and glutathione peroxidase(GPx), reveals synergistic efficiency of ROS scavenging, compared to single antioxidant enzyme delivery. TAT peptide conjugation provided a facile nonendocytosis cell uptake and escape from endosome while moving and aggregating along the cytoskeleton that would allow them to be close to each other at the same time, resulting in the cellular antioxidation cascade reaction. The two-enzyme delivery shows a significant synergistic effect for protecting cells against ROS-induced cell damage and cell cycle arrest. The nanocarrier strategy for enzyme delivery demonstrates that intracellular anti-ROS cascade reactions could be regulated by multifunctional MSNs carrying image fluorophore and relevant antioxidation enzymes.


Assuntos
Antioxidantes/administração & dosagem , Glutationa Peroxidase/administração & dosagem , Nanopartículas/química , Proteínas Recombinantes de Fusão/administração & dosagem , Superóxido Dismutase/administração & dosagem , Antioxidantes/química , Glutationa Peroxidase/química , Células HeLa , Humanos , Nanopartículas/administração & dosagem , Fragmentos de Peptídeos/administração & dosagem , Fragmentos de Peptídeos/química , Desnaturação Proteica , Proteínas Recombinantes de Fusão/química , Dióxido de Silício/administração & dosagem , Dióxido de Silício/química , Superóxido Dismutase/química , Produtos do Gene tat do Vírus da Imunodeficiência Humana/administração & dosagem , Produtos do Gene tat do Vírus da Imunodeficiência Humana/química
9.
PLoS Biol ; 14(1): e1002349, 2016 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-26751069

RESUMO

Replication forks are vulnerable to wayward nuclease activities. We report here our discovery of a new member in guarding genome stability at replication forks. We previously isolated a Drosophila mutation, wuho (wh, no progeny), characterized by a severe fertility defect and affecting expression of a protein (WH) in a family of conserved proteins with multiple WD40 repeats. Knockdown of WH by siRNA in Drosophila, mouse, and human cultured cells results in DNA damage with strand breaks and apoptosis through ATM/Chk2/p53 signaling pathway. Mice with mWh knockout are early embryonic lethal and display DNA damage. We identify that the flap endonuclease 1 (FEN1) is one of the interacting proteins. Fluorescence microscopy showed the localization of WH at the site of nascent DNA synthesis along with other replication proteins, including FEN1 and PCNA. We show that WH is able to modulate FEN1's endonucleolytic activities depending on the substrate DNA structure. The stimulatory or inhibitory effects of WH on FEN1's flap versus gap endonuclease activities are consistent with the proposed WH's functions in protecting the integrity of replication fork. These results suggest that wh is a new member of the guardians of genome stability because it regulates FEN1's potential DNA cleavage threat near the site of replication.


Assuntos
Endonucleases Flap/metabolismo , Proteínas de Ligação ao GTP/metabolismo , Instabilidade Genômica , Animais , Apoptose , Proteínas de Transporte , Replicação do DNA , Proteínas de Drosophila , Drosophila melanogaster , Células HCT116 , Humanos , Camundongos , Camundongos Knockout , Antígeno Nuclear de Célula em Proliferação/metabolismo , Proteína Supressora de Tumor p53/metabolismo
10.
Opt Express ; 23(24): 30943-55, 2015 Nov 30.
Artigo em Inglês | MEDLINE | ID: mdl-26698726

RESUMO

The dual-color dynamic particle tracking approach that uses temporal focusing multiphoton fluorescence excitation and two-channel astigmatic imaging is utilized to track molecular trajectories in three dimensions to explore molecular interactions. Images of two fluorophores were obtained to extract their positions by optical sectioning excitation using a fast temporal focusing multiphoton excitation microscope (TFMPEM) and by the simultaneous collection of data in two channels. The presented pair of cylindrical lenses, which was used to adjust the astigmatism effect with the minimum shifting of the imaging plane, was more feasible and flexible than single cylindrical lens for aligning two separate detection channels in astigmatic imaging. The lateral and axial positioning resolutions were observed to be approximately 9-13 nm and 23-30 nm respectively, for the two fluorescence channels. The dynamic movement and binding behavior of clusters of GM-CSF receptors and JAK2 kinases in HeLa cells in the presence of GM-CSF ligands were observed. Therefore, the proposed dual-color tracking strategy is useful for the dynamic study of molecular interactions in living specimens with a fast frame rate, less photobleaching, better penetration depth, and minimum optical trapping force.


Assuntos
Aumento da Imagem/instrumentação , Janus Quinase 2/metabolismo , Lentes , Microscopia de Fluorescência por Excitação Multifotônica/instrumentação , Imagem Molecular/instrumentação , Receptores de Fator Estimulador das Colônias de Granulócitos e Macrófagos/metabolismo , Ativação Enzimática , Desenho de Equipamento , Análise de Falha de Equipamento , Células HeLa , Humanos , Iluminação/instrumentação , Reprodutibilidade dos Testes , Sensibilidade e Especificidade , Transdução de Sinais/fisiologia
11.
Org Biomol Chem ; 13(45): 11096-104, 2015 Dec 07.
Artigo em Inglês | MEDLINE | ID: mdl-26399751

RESUMO

RNA is a drug target involved in diverse cellular functions and viral processes. Molecules that inhibit the HIV TAR RNA-Tat protein interaction may attenuate Tat/TAR-dependent protein expression and potentially serve as anti-HIV therapeutics. By incorporating positively charged residues with mixed side chain lengths, we designed peptides that bind TAR RNA with enhanced intracellular activity. Tat-derived peptides that were individually substituted with positively charged residues with varying side chain lengths were evaluated for TAR RNA binding. Positively charged residues with different side chain lengths were incorporated at each Arg and Lys position in the Tat-derived peptide to enhance TAR RNA binding. The resulting peptides showed enhanced TAR RNA binding affinity, cellular uptake, nuclear localization, proteolytic resistance, and inhibition of intracellular Tat/TAR-dependent protein expression compared to the parent Tat-derived peptide with no cytotoxicity. Apparently, the enhanced inhibition of protein expression by these peptides was not determined by RNA binding affinity, but by proteolytic resistance. Despite the high TAR binding affinity, a higher binding specificity would be necessary for practical purposes. Importantly, altering the positively charged residue side chain length should be a viable strategy to generate potentially useful RNA-targeting bioactive molecules.


Assuntos
Fármacos Anti-HIV/farmacologia , Regulação Viral da Expressão Gênica/efeitos dos fármacos , Produtos do Gene tat/farmacologia , Repetição Terminal Longa de HIV , HIV/genética , Peptídeos/farmacologia , RNA Viral/genética , Sequência de Aminoácidos , Fármacos Anti-HIV/química , Fármacos Anti-HIV/farmacocinética , Linhagem Celular , Produtos do Gene tat/química , Produtos do Gene tat/farmacocinética , HIV/efeitos dos fármacos , HIV/metabolismo , Infecções por HIV/tratamento farmacológico , Repetição Terminal Longa de HIV/efeitos dos fármacos , Humanos , Peptídeos/química , Peptídeos/farmacocinética , RNA Viral/metabolismo
12.
Chem Commun (Camb) ; 51(37): 7954-7, 2015 May 07.
Artigo em Inglês | MEDLINE | ID: mdl-25865407

RESUMO

Surface thiolation affects the size of gold nanoparticles and the presence of visible luminescence under UV stimulation. We explored these phenomena by analysing alkanethiolate coatings with different carbon chain lengths, from 3-mercaptopropionic acid to 16-mercaptohexadecanoic acid, synthesized by intense X-ray irradiation. Photoluminescence is present for the smallest nanoparticles, but its intensity becomes more intense as the carbon chain length increases, achieving a quantum efficiency of 28% with a 16-mercaptohexadecanoic acid coating.

13.
Nanoscale ; 7(9): 4217-25, 2015 Mar 07.
Artigo em Inglês | MEDLINE | ID: mdl-25672786

RESUMO

Continuous and simultaneous 3D single-particle movement and local pH detection in HeLa cells were demonstrated for the first time by combining fluorescent mesoporous silica nanoparticles (FMSNs) and a single-particle tracking (SPT) technique with a precision of ∼10 nm. FMSNs, synthesized by the co-condensation of both pH-sensitive and reference dyes with a silica/surfactant source, allow long-term reliable ratiometric pH measurements with a precision better than 0.3 pH unit because of their excellent brightness and stability. pH variation in the surrounding area of FMSNs during endocytosis was monitored in real-time. Acidification and low mobility of FMSNs were observed at the early endocytic stage, whereas basification and high mobility of FMSNs were observed at the late stage. Our results indicate that it is possible to monitor local pH changes in the environments surrounding nanoparticles during the cellular uptake process of FMSNs, which provides much needed information for designing an efficient drug delivery nanosystem.


Assuntos
Microscopia de Fluorescência , Nanopartículas/metabolismo , Dióxido de Silício/química , Endocitose , Transferência Ressonante de Energia de Fluorescência , Corantes Fluorescentes/química , Células HeLa , Humanos , Concentração de Íons de Hidrogênio , Nanopartículas/química , Nanopartículas/ultraestrutura , Tensoativos/química
14.
Opt Express ; 22(22): 27290-9, 2014 Nov 03.
Artigo em Inglês | MEDLINE | ID: mdl-25401879

RESUMO

A three-dimensional (3D) single fluorescent particle tracking strategy based on temporal focusing multiphoton excitation microscopy (TFMPEM) combined with astigmatism imaging is proposed for delivering nanoscale-level axial information that reveals 3D trajectories of single fluorospheres in the axially-resolved multiphoton excitation volume without z-axis scanning. Whereas other scanning spatial focusing multiphoton excitation schemes induce optical trapping interference, temporal focusing multiphoton excitation produces widefield illumination with minimum optical trapping force on the fluorospheres. Currently, the lateral and axial positioning resolutions of the dynamic particle tracking approach are about 14 nm and 21 nm in standard deviation, respectively. Furthermore, the motion behavior and diffusion coefficients of fluorospheres in glycerol solutions with different concentrations are dynamically measured at a frame rate up to 100 Hz. This TFMPEM with astigmatism imaging holds great promise for exploring dynamic molecular behavior deep inside biotissues via its superior penetration, reduced trapping effect, fast frame rate, and nanoscale-level positioning.

15.
Biomed Opt Express ; 5(8): 2526-36, 2014 Aug 01.
Artigo em Inglês | MEDLINE | ID: mdl-25136483

RESUMO

In this study, the light diffraction of temporal focusing multiphoton excitation microscopy (TFMPEM) and the excitation patterning of nonlinear structured-illumination microscopy (NSIM) can be simultaneously and accurately implemented via a single high-resolution digital micromirror device. The lateral and axial spatial resolutions of the TFMPEM are remarkably improved through the second-order NSIM and projected structured light, respectively. The experimental results demonstrate that the lateral and axial resolutions are enhanced from 397 nm to 168 nm (2.4-fold) and from 2.33 µm to 1.22 µm (1.9-fold), respectively, in full width at the half maximum. Furthermore, a three-dimensionally rendered image of a cytoskeleton cell featuring ~25 nm microtubules is improved, with other microtubules at a distance near the lateral resolution of 168 nm also able to be distinguished.

16.
Glycobiology ; 24(11): 1022-35, 2014 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-24996823

RESUMO

Galectin-3 has been reported to regulate the functions of a number of immune cell types. We previously reported that galectin-3 is translocated to immunological synapses in T cells upon T-cell receptor engagement, where it associates with ALG-2-interacting protein X (Alix). Alix is known to coordinate with the endosomal sorting complex required for transport (ESCRT) to promote human immunodeficiency virus (HIV)-1 virion release. We hypothesized that galectin-3 plays a role in HIV-1 viral budding. Cotransfection of cells of the Jurkat T line with galectin-3 and HIV-1 plasmids resulted in increased HIV-1 budding, and suppression of galectin-3 expression by RNAi in Hut78 and primary CD4+ T cells led to reduced HIV-1 budding. We used immunofluorescence microscopy to observe the partial colocalization of galectin-3, Alix and Gag in HIV-1-infected cells. Results from co-immunoprecipitation experiments indicate that galectin-3 expression promotes Alix-Gag p6 association, whereas the results of Alix knockdown suggest that galectin-3 promotes HIV-1 budding through Alix. HIV-1 particles released from galectin-3-expressing cells acquire the galectin-3 protein in an Alix-dependent manner, with proteins primarily residing inside the virions. We also found that the galectin-3 N-terminal domain interacts with the proline-rich region of Alix. Collectively, these results suggest that endogenous galectin-3 facilitates HIV-1 budding by promoting the Alix-Gag p6 association.


Assuntos
Proteínas de Ligação ao Cálcio/fisiologia , Proteínas de Ciclo Celular/fisiologia , Complexos Endossomais de Distribuição Requeridos para Transporte/fisiologia , Galectina 3/fisiologia , HIV-1/fisiologia , Replicação Viral/fisiologia , Produtos do Gene gag do Vírus da Imunodeficiência Humana/fisiologia , Ligação Proteica
17.
Opt Express ; 22(24): 29388-97, 2014 Dec 01.
Artigo em Inglês | MEDLINE | ID: mdl-25606873

RESUMO

Cyanine dye J-aggregate films are a class of absorbing and luminescent materials which have been extensively applied in the polariton-based research. Here we systematically study the DEDOC cyanine dyes J-aggregate films made by layer-by-layer assembly and spin-coating processes to establish a clear correlation between the film structure and the absorption and luminescence properties. From detailed analyses of morphology, optical spectra, and light-emitting diode characteristics, we demonstrate that layer-by-layer assembled film has higher degrees of homogeneity and molecular packing quality than spin-coated film, leading to a higher absorption coefficient, more uniform luminescence, and a greater electroluminescence quantum efficiency with maximized thickness.


Assuntos
Absorção de Radiação , Carbocianinas/química , Corantes/química , Eletricidade , Luminescência , Eletrônica , Vidro/química , Microscopia de Força Atômica , Análise Espectral
18.
Nanoscale ; 5(3): 1018-25, 2013 Feb 07.
Artigo em Inglês | MEDLINE | ID: mdl-23249951

RESUMO

Herein, we describe a simple fabrication procedure for creating artificial hierarchical micro/nanopillars on silicon substrates that allows an effective, precise control of the interfacial adhesion and surface hydrophobicity. These well-defined hierarchical micro/nanostructures have four possible wetting states: Cassie-Cassie (C-C), Cassie-Wenzel (C-W), Wenzel-Cassie (W-C) and Wenzel-Wenzel (W-W). By controlling the critical height of the micro/nanopillars, it is possible to fabricate hierarchical micro/nanostructures in these four states. Thus, the hierarchical superhydrophobic surfaces proposed and fabricated in this study are promising for mimicking either lotus leaves with low adhesion or rose petals with high adhesion.


Assuntos
Cristalização/métodos , Modelos Químicos , Modelos Moleculares , Nanoestruturas/química , Nanoestruturas/ultraestrutura , Adesividade , Simulação por Computador , Substâncias Macromoleculares/química , Conformação Molecular , Tamanho da Partícula , Propriedades de Superfície
19.
Bioconjug Chem ; 23(11): 2173-82, 2012 Nov 21.
Artigo em Inglês | MEDLINE | ID: mdl-23030814

RESUMO

In the present study, we demonstrate the synthesis and applications of multifunctional gold nanorod-based probes for specific targeting and noninvasive imaging based on localized heating generated by gold nanorods after NIR irradiation. The structural design of the probe consists of MUA (11-mercaptoundecanoic acid)-capped gold nanorods covalently linked with low-molecular-weight chitosan oligosaccharide (M(w) ~5000) via carbodiimide (EDC) coupling agent. This surface modification is performed for complete replacement of toxic CTAB (hexadecyltrimethyl-ammonium chloride) and acid-responsive delivery of gold nanorods in acidic environment as known to be present at tumor surrounding areas. The resulting chitosan oligosaccharide-modified gold nanorods (CO-GNRs) were further conjugated with tumor targeting monoclonal antibody against EGFR (epidermal growth factor receptor) to provide localized targeting functionality owing to the overexpression of EGFR in human oral adenosquamous carcinoma cell line CAL 27. Initial in vitro and in vivo toxicity assessments indicated that CO-GNRs did not induce any significant toxicity and are thus suitable for biological applications. Furthermore, selective targeting and accumulation of CO-GNRs were observed in vitro via two-photon luminescence imaging studies in CAL 27, which was also observed through in vivo targeting studies performed via NIR (near-infrared) laser irradiation in CAL 27 xenografts of BALB/c nude mice. Hence, the CO-GNRs that we have developed are biocompatible and nontoxic and can be a potential candidate for in vivo targeted delivery, noninvasive imaging based on localized hyperthermia, and photothermal-related therapies.


Assuntos
Sistemas de Liberação de Medicamentos , Sondas Moleculares/farmacologia , Animais , Anticorpos Monoclonais/imunologia , Reações Antígeno-Anticorpo , Células CHO , Linhagem Celular Tumoral , Sobrevivência Celular/efeitos dos fármacos , Quitosana/química , Cricetinae , Relação Dose-Resposta a Droga , Receptores ErbB/genética , Receptores ErbB/imunologia , Ouro/química , Humanos , Raios Infravermelhos , Medições Luminescentes , Masculino , Camundongos , Camundongos Endogâmicos BALB C , Camundongos Nus , Sondas Moleculares/síntese química , Sondas Moleculares/química , Nanotubos/química , Oligossacarídeos/química , Fótons , Relação Estrutura-Atividade , Propriedades de Superfície , Distribuição Tecidual
20.
Cell Cycle ; 11(19): 3611-26, 2012 Oct 01.
Artigo em Inglês | MEDLINE | ID: mdl-22935703

RESUMO

It is well known that ligand binding to the high-affinity GM-CSF receptor (GMR) activates JAK2. However, how and where this event occurs in a cellular environment remains unclear. Here, we demonstrate that clathrin- but not lipid raft-mediated endocytosis is crucial for GMR signaling. Knockdown expression of clathrin heavy chain or intersectin 2 (ITSN2) attenuated GMR-mediated activation of JAK2, whereas inhibiting clathrin-coated pits or plagues to bud off the membrane by the dominant-negative mutant of dynamin enhanced such event. Moreover, unlike the wild-type receptor, an ITSN2-non-binding mutant of GMR defective in targeting to clathrin-coated pits or plagues [collectively referred to as clathrin-coated structures (CCSs) here] failed to activate JAK2 at such locations. Additional experiments demonstrate that ligand treatment not only enhanced JAK2/GMR association at CCSs, but also induced a conformational change of JAK2 which is required for JAK2 to be activated by CCS-localized CK2. Interestingly, ligand-independent activation of the oncogenic mutant of JAK2 (JAK2V617F) also requires the targeting of this mutant to CCSs. But JAK2V617F seems to be constitutively in an open conformation for CK2 activation. Together, this study reveals a novel functional role of CCSs in GMR signaling and the oncogenesis of JAK2V617F.


Assuntos
Clatrina/metabolismo , Invaginações Revestidas da Membrana Celular/metabolismo , Janus Quinase 2/metabolismo , Receptores de Fator Estimulador das Colônias de Granulócitos e Macrófagos/metabolismo , Proteínas Adaptadoras de Transporte Vesicular/metabolismo , Motivos de Aminoácidos , Sequência de Aminoácidos , Animais , Endocitose , Ativação Enzimática , Células HeLa , Humanos , Ligantes , Camundongos , Modelos Biológicos , Dados de Sequência Molecular , Proteínas Mutantes/metabolismo , Mutação/genética , Ligação Proteica , Conformação Proteica , Transporte Proteico , Receptores de Fator Estimulador das Colônias de Granulócitos e Macrófagos/química , Transdução de Sinais
SELEÇÃO DE REFERÊNCIAS
DETALHE DA PESQUISA
...