Your browser doesn't support javascript.
Mostrar: 20 | 50 | 100
Resultados 1 - 20 de 2.589
Filtrar
Mais filtros










Base de dados
Intervalo de ano de publicação
1.
Chemosphere ; 244: 125532, 2020 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-32050334

RESUMO

Hierarchical Co3O4@MnOx material has been synthesized by in-suit growth of MnOx on the Co3O4 and applied in catalytic oxidation of volatile organic compounds (VOCs). Results revealed that T90 of acetone on the Co3O4@MnOx was 195 °C, which was 36 °C and 32 °C lower than that on the Co3O4 and MnOx/Co3O4, respectively. The universality experiments demonstrated that T90 of ethyl acetate and toluene on the Co3O4@MnOx were 200 °C and 222 °C, respectively. The above results indicated that Co3O4@MnOx catalyst presented a robust catalytic performance. Characterization results showed that high catalytic activity of the Co3O4@MnOx catalyst could be attributed to the improvement of low temperature reducibility, the enhancement of Co3+ and adsorbed oxygen species resulted from the sufficient reaction between MnO4- and Co2+ during secondary hydrothermal process. Furthermore, stability and water-resistance experiments showed the Co3O4@MnOx catalyst with high cycle and long-term stability, satisfied endurability to 5.5-10 vol. % water vapor at 210 °C.


Assuntos
Modelos Químicos , Nanofios/química , Compostos Orgânicos Voláteis/química , Adsorção , Catálise , Oxirredução , Óxidos , Oxigênio , Tolueno
2.
Chem Commun (Camb) ; 56(10): 1513-1516, 2020 Feb 04.
Artigo em Inglês | MEDLINE | ID: mdl-31919482

RESUMO

A potentiometric resolved photoelectrochemical (PEC) system based on CdS nanowires and SnNb2O6 nanosheets was developed. To prove the applicability of this system in PEC multi-biomarker analysis, a label free PEC immunosensor for two cardiac biomarkers, myoglobin and cardiac troponin I, was constructed.


Assuntos
Biomarcadores/análise , Técnicas Eletroquímicas/métodos , Nanoestruturas/química , Nanofios/química , Compostos de Estanho/química , Técnicas Biossensoriais , Compostos de Cádmio/química , Humanos , Mioglobina/análise , Sulfetos/química , Troponina I/análise
3.
Chem Commun (Camb) ; 56(3): 470-473, 2020 Jan 02.
Artigo em Inglês | MEDLINE | ID: mdl-31828262

RESUMO

By assembling DNAzyme on DNA nanowires through DNA hybridization, we have developed a novel accelerated DNAzyme-based fluorescent nanoprobe for fast, sensitive and selective detection of miRNA. Moreover, the strategy was successfully applied for in situ imaging of miRNA-21 in different cell lines.


Assuntos
DNA Catalítico/química , Corantes Fluorescentes/química , MicroRNAs/análise , Microscopia Confocal , Nanofios/química , Linhagem Celular Tumoral , Humanos , Limite de Detecção , MicroRNAs/metabolismo , Hibridização de Ácido Nucleico , Espectrometria de Fluorescência
4.
Ecotoxicol Environ Saf ; 185: 109739, 2019 Dec 15.
Artigo em Inglês | MEDLINE | ID: mdl-31586847

RESUMO

Silver nanowires (AgNWs) are widely produced in many electronic and optical products, and could be inevitably discharged into the aquatic environments. Sulfidation is one of the most important transformation processes of AgNWs, and could significantly affect their fate and interactions with other pollutants in aquatic environment. In the present study, the sulfidation products of AgNWs with different atomic ratio of Ag and S were prepared under environmentally relevant conditions. The crystal structure, elemental composition, morphology and size of the sulfidation products were comprehensively characterized by powder X-ray diffraction, UV-vis spectroscopy, X-ray photoelectron spectroscopy and transmission electron microscope. The products were heterostructured nanowires and the Ag2S/Ag molar ratio increased with extension of the reaction time. The produced Ag2S-Ag nanowires displayed a good photocatalytic activity and facilitated the degradation of the copresent organic pollutant bisphenol A (BPA) under simulated sunlight irradiation. As sulfidation time increased, more Ag2S was generated and the Ag2S-Ag composites displayed high promotion effect on BPA degradation. This effect could be ascribed to the favorable synergistic effects between Ag2S and AgNWs, such as high electron-hole separation efficiency and low charge transfer resistance. The chemical scavenger experiments demonstrated that superoxide anion radicals and photogenerated holes in the sulfidation products of AgNWs could be the main reactive species for photocatalytic degradation.


Assuntos
Compostos Benzidrílicos/análise , Nanofios/química , Fenóis/análise , Prata/química , Sulfetos/química , Luz Solar , Poluentes Químicos da Água/análise , Compostos Benzidrílicos/efeitos da radiação , Catálise , Fenóis/efeitos da radiação , Poluentes Químicos da Água/efeitos da radiação
5.
Ecotoxicol Environ Saf ; 186: 109742, 2019 Dec 30.
Artigo em Inglês | MEDLINE | ID: mdl-31593826

RESUMO

Safety concerns have been raised with regard to silver nanowires (AgNWs) because of their extensive applications. Recently, ultralong AgNWs have shown physical properties superior to those of short AgNWs. However, little is known about their toxicity and potential risks. In this study, we demonstrated a series of ultralong AgNWs-induced biological effects in human lung cancer epithelial cells (A549). Ultralong AgNWs treatments induced ROS generation, mitochondria-mediated apoptosis, and self-protective autophagy at nonlethal concentrations. In contrast to some previous reports, apoptosis was found not to correlate with the reduction of intracellular ROS. Measuring the processing of ROS generation, apoptosis and autophagy, we demonstrated that ROS not only enhance mitochondrial damage, but also raise protective autophagic flux in ultralong AgNW-treated cells. Moreover, ultralong AgNWs were found to be internalized into the cytoplasm of the epithelial cells. This study not only investigates ultralong AgNWs-induced cytotoxicity but also pinpoints ROS as a key signal in mechanisms of their toxicity.


Assuntos
Autofagia/efeitos dos fármacos , Nanofios/toxicidade , Espécies Reativas de Oxigênio/metabolismo , Prata/toxicidade , Células A549 , Apoptose/efeitos dos fármacos , Células Epiteliais/efeitos dos fármacos , Células Epiteliais/patologia , Humanos , Mitocôndrias/efeitos dos fármacos , Mitocôndrias/patologia , Nanofios/química , Tamanho da Partícula , Prata/química
6.
Chemphyschem ; 20(23): 3177-3180, 2019 12 03.
Artigo em Inglês | MEDLINE | ID: mdl-31639248

RESUMO

Herein, we report ultrasound-propelled graphene-oxide coated gold nanowire motors, functionalized with fluorescein-labeled DNA aptamers (FAM-AIB1-apt), for qualitative detection of overexpressed AIB1 oncoproteins in MCF-7 breast cancer cells. The movement of nanomotors under the ultrasound field facilitated intracellular uptake and resulted in a faster aptamer binding with the target protein and thus faster fluorescence recovery. The propulsion behavior of the aptamer functionalized nanomotors greatly enhanced the fluorescence intensity compared to static conditions. The new aptamer@nanomotor-based strategy offers considerable potential for further development of sensing methodologies towards diagnosis of breast cancer.


Assuntos
Aptâmeros de Nucleotídeos/metabolismo , Fluoresceína/química , Aptâmeros de Nucleotídeos/química , Neoplasias da Mama/diagnóstico , Neoplasias da Mama/metabolismo , Neoplasias da Mama/patologia , Feminino , Ouro/química , Humanos , Células MCF-7 , Microscopia Eletrônica de Varredura , Nanotecnologia/instrumentação , Nanotecnologia/métodos , Nanofios/química , Sonicação
7.
Sensors (Basel) ; 19(20)2019 Oct 17.
Artigo em Inglês | MEDLINE | ID: mdl-31627298

RESUMO

Rather than the internal genome nucleic acids, the biomolecules on the surface of the influenza virus itself should be detected for a more exact and rapid point-of-care yes/no decision for influenza virus-induced infectious diseases. This work demonstrates the ultrasensitive electrical detection of the HA1 domain of hemagglutinin (HA), a representative viral surface protein of the influenza virus, using the top-down complementary metal oxide semiconductor (CMOS) processed silicon nanowire (SiNW) field-effect transistor (FET) configuration. Cytidine-5'-monophospho-N-acetylneuraminic acid (CMP-NANA) was employed as a probe that specifically binds both to the aldehyde self-aligned monolayer on the SiNWs and to HA1 simultaneously. CMP-NANA was serially combined with two kinds of linkers, namely 3-aminopropyltriethoxysilane and glutaraldehyde. The surface functionalization used was verified using the purification of glutathione S-transferase-tagged HA1, contact angle measurement, enzyme-linked immunosorbent assay test, and isoelectric focusing analysis. The proposed functionalized SiNW FET showed high sensitivities of the threshold voltage shift (ΔVT) ~51 mV/pH and the ΔVT = 112 mV (63 mV/decade) with an ultralow detectable range of 1 fM of target protein HA1.


Assuntos
Técnicas Biossensoriais , Hemaglutininas/isolamento & purificação , Infecções por Orthomyxoviridae/diagnóstico , Orthomyxoviridae/isolamento & purificação , Animais , Humanos , Nanofios/química , Orthomyxoviridae/patogenicidade , Sistemas Automatizados de Assistência Junto ao Leito , Silício
8.
Chemosphere ; 237: 124565, 2019 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-31549664

RESUMO

Long silver nanowires (AgNWs, >5 µm) have shown promising applications in next generation biomaterials. However, the toxicity of long AgNWs is not well characterized in terms of their size. In this study, five AgNWs types, including SAgNW30 (length: 5-10 µm; diameter: 30 nm), MAgNW30 (length: 20-30 µm; diameter: 30 nm), LAgNW30 (length: ∼100 µm; diameter: 30 nm), LAgNW50 (length: ∼100 µm; diameter: 50 nm), and LAgNW100 (length: ∼100 µm; diameter: 100 nm), were used to investigate the size-dependent phagocytosis and cytotoxicity in macrophage. It showed that SAgNW30, MAgNW30, LAgNW30 can be fully phagocytosed by macrophages, but LAgNW50 and LAgNW100 frustrated the phagocytosis. It demonstrated that LAgNW30 can be internalized into macrophage in a curly manner. The size-dependent cytotoxicity was observed in cell viability, apoptosis, mitochondrial damage, phenotypic transition, and inflammatory response in AgNWs-treated macrophage. The AgNWs-induced cytotoxicity was depended on their length and diameter, increased gradually in the order of SAgNW30 > MAgNW30 > LAgNW30 > LAgNW50 > LAgNW100. The findings presented here will assist in the evaluation of the size-dependent cytotoxicity mediated by long AgNWs.


Assuntos
Macrófagos/efeitos dos fármacos , Nanofios/química , Nanofios/toxicidade , Fagocitose/efeitos dos fármacos , Animais , Sobrevivência Celular/efeitos dos fármacos , Macrófagos/patologia , Potencial da Membrana Mitocondrial/efeitos dos fármacos , Camundongos , Células RAW 264.7 , Prata/química , Prata/toxicidade
9.
Soft Matter ; 15(37): 7490-7500, 2019 Sep 25.
Artigo em Inglês | MEDLINE | ID: mdl-31513228

RESUMO

Internalization of particles by cells plays a crucial role for adsorbing nutrients and fighting infection. Endocytosis is one of the most important mechanisms of particle uptake, which encompasses multiple pathways. Although endocytosis is a complex mechanism involving biochemical signaling and active force generation, the energetic cost associated with the large deformations of the cell membrane wrapping around a foreign particle is an important factor controlling this process, which can be studied using quantitative physical models. Of particular interest is the competition between membrane-cytoskeleton and membrane-target adhesion. This competitive adhesion mechanism can be reproduced to some extent by studying particle wrapping by a membrane adhered to a substrate. We propose a theoretical analysis of this process. Here, we explore the wrapping of a lipid membrane around a long cylindrical object in the presence of a substrate mimicking the cytoskeleton. Using discretization of the Helfrich elastic energy, which accounts for the membrane bending rigidity and surface tension, we obtain a wrapping phase diagram as a function of the membrane-cytoskeleton and the membrane-target adhesion energy, which includes unwrapped, partially wrapped and fully wrapped states. We provide an analytical expression for the boundary between the different regimes. While the transition to partial wrapping is independent of the membrane tension, the transition to full wrapping is very much influenced by the membrane tension. We also show that target wrapping may proceed in an asymmetric fashion in the full wrapping regime.


Assuntos
Bicamadas Lipídicas/química , Modelos Teóricos , Nanofios/química , Membrana Celular/química , Citoesqueleto/química , Elasticidade , Termodinâmica
10.
Mater Sci Eng C Mater Biol Appl ; 104: 109940, 2019 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-31500050

RESUMO

Well-dispersed Ag nanowires and PVP-modified BaGdF5: Yb3+, Er3+ spherical nanoparticles were prepared by simple solvothermal and hydrothermal method, and they were further combined to obtain photo-thermal-magnetic multifunctional Ag/BaGdF5: Yb3+, Er3+ nanocomposites. Under NIR laser irradiation, monodispersed rare-earth fluoride BaGdF5: Yb3+, Er3+ in nanocomposite exhibit good upconversion fluorescent. Meanwhile, under the action of an external magnetic field, the nanocomposite also exhibits good magnetic properties and excellent contrast efficiency by CT/MR imaging. The NCs possess good structure and photothermal stability at multiple cycles due to that Ag nanowires are modified by polyvinyl pyrrolidone and sodium citrate. The biocompatibility and low toxicity of NCs are also remarkable. Importantly, the unique linear morphology of Ag particles can achieve high efficiency conversion between light and heat. Furthermore, in vitro tests also confirm the high efficiency of photothermal therapy for cancer cells.


Assuntos
Fluoretos/química , Fluoretos/uso terapêutico , Nanocompostos/química , Nanopartículas/química , Nanofios/química , Neoplasias/tratamento farmacológico , Prata/química , Linhagem Celular Tumoral , Corantes Fluorescentes/química , Células HeLa , Células Hep G2 , Humanos , Luz , Luminescência , Metais Terras Raras/química , Itérbio/química
11.
Anal Chim Acta ; 1082: 176-185, 2019 Nov 15.
Artigo em Inglês | MEDLINE | ID: mdl-31472706

RESUMO

We report herein a novel multiple electrochemical aptasensor based on covalent-organic framework (COF) for sensitive and simultaneous detection of miRNA 155 and miRNA 122, by using shell-encoded gold nanoparticles (Au NPs) as signal labels (AgNCs@AuNPs and Cu2O@AuNPs, respectively, NCs = nanoclusters). A new COF nanowire was synthesized via condensation polymerization of 1,3,6,8-tetra(4-carboxylphenyl)pyrene and melamine (represented by TBAPy-MA-COF-COOH) for multiple aptasensor fabrication. The nanowire was then used as a platform for anchoring single-strand DNA (ssDNA), which was hybridized with the complementary aptamer (cApt) probes of miRNA 155 and miRNA 122. AgNCs@AuNPs and Cu2O@AuNPs modified with cApts show separated differential pulse voltammetry (DPV) peaks at 0.08 and -0.1 V, respectively. The signal labels immobilized with cApts were released from the hybridized DNA complex and bound to their corresponding targets when contacting miRNAs. This phenomenon results in the substantial decline of the DPV peak current density of the signal labels. The developed TBAPy-MA-COF-COOH-based aptasensor has superior performance for sensing miRNA 155 and miRNA 122 simultaneously, with ultrasensitive low detection limits of 6.7 and 1.5 fM (S/N = 3), respectively, a wide linear range of 0.01-1000 pM, and high selectivity and applicability for serum samples. The proposed TBAPy-MA-based aptasensor demonstrates potential for simultaneous detection of multiple cancer biomarkers by replacing other ssDNA and aptamer strands.


Assuntos
Nanopartículas Metálicas/química , MicroRNAs/sangue , Nanofios/química , Polímeros/química , Aptâmeros de Nucleotídeos/química , Aptâmeros de Nucleotídeos/genética , Técnicas Biossensoriais/métodos , DNA de Cadeia Simples/química , DNA de Cadeia Simples/genética , Ouro/química , Humanos , Limite de Detecção , Hibridização de Ácido Nucleico , Pirenos/química , Reprodutibilidade dos Testes , Triazinas/química
12.
Molecules ; 24(18)2019 Sep 06.
Artigo em Inglês | MEDLINE | ID: mdl-31489942

RESUMO

Strong piezoresistivity of InAsP nanowires is rationalized with atomistic simulations coupled to Density Functional Theory. With a focal interest in the case of the As(75%)-P(25%) alloy, the role of crystal phases and phosphorus atoms in strain-driven carrier conductance is discussed with a direct comparison to nanowires of a single crystal phase and a binary (InAs) alloy. Our analysis of electronic structures presents solid evidences that the strong electron conductance and its sensitivity to external tensile stress are due to the phosphorous atoms in a Wurtzite phase, and the effect of a Zincblende phase is not remarkable. With several solid connections to recent experimental studies, this work can serve as a sound framework for understanding of the unique piezoresistive characteristics of InAsP nanowires.


Assuntos
Arsenicais/química , Índio/química , Nanofios/química , Fósforo/química , Teoria da Densidade Funcional , Condutividade Elétrica , Tamanho da Partícula , Propriedades de Superfície
13.
ACS Appl Mater Interfaces ; 11(41): 38116-38125, 2019 Oct 16.
Artigo em Inglês | MEDLINE | ID: mdl-31545034

RESUMO

Humidity sensors have broad applications in health monitoring, environmental protection and human-machine interface, and robotics. Here, we developed a humidity sensor using alkali oxidation method to grow in situ TiO2 nanowires on two-dimensional Ti3C2 MXene. With an order of magnitude larger surface area compared to pure Ti3C2 or TiO2 materials, the urchin-like Ti3C2/TiO2 composite demonstrates a record high sensitivity in a low relative humidity (RH) environment (∼280 pF/% RH from 7% RH to 33% RH). Complex impedance spectroscopy and Schottky junction theory were employed to understand the underlying sensing mechanisms of the Ti3C2/TiO2 composite under various humidity conditions. We demonstrate the application of humidity sensors made with the Ti3C2/TiO2 composite for noncontact detection of the presence of various liquids as well as human fingers.


Assuntos
Umidade , Nanofios/química , Titânio/química , Animais , Ouriços-do-Mar
14.
Sensors (Basel) ; 19(15)2019 Aug 05.
Artigo em Inglês | MEDLINE | ID: mdl-31387246

RESUMO

The development of sensors with high sensitivity, good flexibility, low cost, and capability of detecting multiple inputs is of great significance for wearable electronics. Herein, we report a napkin-based wearable capacitive sensor fabricated by a novel, low-cost, and facile strategy. The capacitive sensor is composed of two pieces of electrode plates manufactured by spontaneous assembly of silver nanowires (NWs) on a polydimethylsiloxane (PDMS)-patterned napkin. The sensor possesses high sensitivity (>7.492 kPa-1), low cost, and capability for simultaneous detection of multiple signals. We demonstrate that the capacitive sensor can be applied to identify a variety of human physiological signals, including finger motions, eye blinking, and minute wrist pulse. More interestingly, the capacitive sensor comfortably attached to the temple can simultaneously monitor eye blinking and blood pulse. The demonstrated sensor shows great prospects in the applications of human-machine interface, prosthetics, home-based healthcare, and flexible touch panels.


Assuntos
Monitorização Fisiológica/métodos , Dispositivos Eletrônicos Vestíveis , Piscadela/fisiologia , Dimetilpolisiloxanos/química , Dedos/fisiologia , Frequência Cardíaca/fisiologia , Humanos , Monitorização Fisiológica/instrumentação , Nanofios/química , Prata/química , Dispositivos Eletrônicos Vestíveis/economia
15.
Biosens Bioelectron ; 142: 111545, 2019 Oct 01.
Artigo em Inglês | MEDLINE | ID: mdl-31376712

RESUMO

We propose a spectral contrast method to map the transmission images of surface plasmon resonance (SPR) in metallic nanostructures. Comparing the intensities between two neighboring wavelength bands near the SPR wavelength, the signal-to-noise ratio for biosensing applications obtained using the proposed method is found to be ten times higher than that obtained by conventional intensity analysis and 1.6 times better than that obtained by peak-wavelength fitting. The dynamic range and linearity of the refractive index are comparable to the peak-wavelength shift measurement. Based on the detection method, a spectral modulation system for the optical microscope is developed, combined with a gold-capped nanowire array, to measure the biointeractions in microfluidic devices. The experimental results show that the proposed method obtained multiple detections with a detection limit of 1.04 × 10-5 refractive index units. Two types of analysis methods for SPR images are used to study the protein-antibody interactions. The region-of-interest analysis supports multiplexing detections in a compact microfluidic sensor. The effective pixel analysis eliminates low-response pixels and enhances the signal-to-noise ratios for sensitive label-free detection.


Assuntos
Ouro/química , Nanoestruturas/química , Imagem Óptica/métodos , Ressonância de Plasmônio de Superfície/métodos , Desenho de Equipamento , Glucose/análise , Nanofios/química , Imagem Óptica/instrumentação , Refratometria , Ressonância de Plasmônio de Superfície/instrumentação
16.
Adv Mater ; 31(39): e1903095, 2019 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-31410882

RESUMO

Mimicking brain-like functionality with an electronic device is an essential step toward the design of future technologies including artificial visual and memory applications. Here, a proof-of-concept all-oxide-based (NiO/TiO2 ) highly transparent (54%) heterostructure is proposed and demonstrated, which mimics the primitive functions of the visual cortex. Specifically, orientation selectivity and spatiotemporal processing similar to that of the visual cortex are demonstrated using direct optical stimuli under the self-biased condition due to photovoltaic effect, illustrating an energy-efficient approach for neuromorphic computing. The photocurrent of the device can be modulated from zero to 80 µA by simply rotating the slit by 90°. The device shows fast rise and fall times of 3 and 6 ms, respectively. Based on Kelvin probe force measurements, the observed results are attributed to a lateral photovoltaic effect. This highly transparent, self-biased, photonic triggered device paves the way for the advancement of energy-efficient neuromorphic computation.


Assuntos
Biomimética/instrumentação , Equipamentos e Provisões Elétricas , Fenômenos Ópticos , Fótons , Córtex Visual/fisiologia , Nanofios/química , Níquel/química , Prata/química , Titânio/química
17.
J Mater Sci Mater Med ; 30(8): 96, 2019 Aug 14.
Artigo em Inglês | MEDLINE | ID: mdl-31414231

RESUMO

Critical size bone defects that do not heal spontaneously are among the major reasons for the disability in majority of people with locomotor disabilities. Tissue engineering has become a promising approach for repairing such large tissue injuries including critical size bone defects. Three-dimension (3D) porous scaffolds based on piezoelectric polymers like poly(vinylidene fluoride-trifluoroethylene) (P(VDF-TrFE)) have received a lot of attention in bone tissue engineering due to their favorable osteogenic properties. Owing to the favourable redox properties, titanium dioxide (TiO2) nanostructures have gained a great deal of attention in bone tissue engineering. In this paper, tissue engineering scaffolds based on P(VDF-TrFE) loaded with TiO2 nanowires (TNW) were developed and evaluated for bone tissue engineering. Wet-chemical method was used for the synthesis of TNW. Obtained TNW were thoroughly characterized for the physicochemical and morphological properties using techniques such as X-Ray diffraction (XRD) analysis and transmission electron microscopy (TEM). Electrospinning was used to produce TNW incorporated P(VDF-TrFE) scaffolds. Developed scaffolds were characterized by state of art techniques such as Scanning Electron Microscopy (SEM), XRD and Differential scanning calorimetry (DSC) analyses. TEM analysis revealed that the obtained TiO2 nanostructures possess nanofibrous morphology with an average diameter of 26 ± 4 nm. Results of characterization of nanocomposite scaffolds confirmed the effective loading of TNW in P(VDF-TrFE) matrix. Fabricated P(VDF-TrFE)/TNW scaffolds possessed good mechanical strength and cytocompatibility. Osteoblast like cells showed higher adhesion and proliferation on the nanocomposite scaffolds. This investigation revealed that the developed P(VDF-TrFE) scaffolds containing TNW can be used as potential scaffolds for bone tissue engineering applications.


Assuntos
Osso e Ossos/citologia , Nanofios/química , Polivinil/química , Engenharia Tecidual , Tecidos Suporte/química , Titânio/química , Compostos de Vinila/química , Animais , Materiais Biocompatíveis/síntese química , Materiais Biocompatíveis/química , Materiais Biocompatíveis/farmacologia , Proliferação de Células/efeitos dos fármacos , Células Cultivadas , Fibroblastos/citologia , Fibroblastos/efeitos dos fármacos , Fibroblastos/fisiologia , Hidrocarbonetos Fluorados/química , Teste de Materiais , Camundongos , Nanocompostos/química , Osteoblastos/citologia , Osteoblastos/efeitos dos fármacos , Osteoblastos/fisiologia , Ratos , Engenharia Tecidual/instrumentação , Engenharia Tecidual/métodos
18.
Biosens Bioelectron ; 143: 111593, 2019 Oct 15.
Artigo em Inglês | MEDLINE | ID: mdl-31442750

RESUMO

Accurate and sensitive detection of the Pax-5a gene is of great importance in the early diagnosis and prognosis of acute leukaemia. Herein, a label-free electrochemical sensing system was proposed for the detection of the acute leukaemia Pax-5a gene based on enzyme-assisted signal amplification to generate abundant G-quadruplex/hemin DNAzyme. The presence of Pax-5a can open the hairpin probe (HP), which acts as a template. Under the action of the restriction enzymes Nt.BbvCI and Klenow fragment polymerase, the target gene Pax-5a is cycled to open the HP; On the other hand, a large number of G-quadruplex sequences are produced. The resulting G-quadruplex sequence is capable of forming the G-quadruplex/hemin complex on the surface of the electrode in the presence of hemin. The ultrasensitive label-free electrochemical detection of Pax-5a can be realized via the G-quadruplex/hemin complex-catalysed reduction of H2O2, and the detection limit was estimated to be as low as 4.6 fM. In addition, the biosensor has good specificity and stability, and also has excellent detection capabilities in a complex substrate environment. Therefore, the sensor shows great potential in bioanalysis and clinical diagnosis.


Assuntos
Técnicas Biossensoriais , Técnicas Eletroquímicas , Leucemia/diagnóstico , Fator de Transcrição PAX5/isolamento & purificação , DNA Catalítico/química , Quadruplex G , Humanos , Peróxido de Hidrogênio/química , Leucemia/genética , Limite de Detecção , Nanofios/química , Técnicas de Amplificação de Ácido Nucleico/métodos , Fator de Transcrição PAX5/genética
19.
Environ Int ; 132: 105105, 2019 11.
Artigo em Inglês | MEDLINE | ID: mdl-31437644

RESUMO

Increasing concentrations of anthropogenic antibiotics and their metabolites in aqueous environments has caused growing concerns over the proliferation of antibiotic resistance and potential adverse impacts to agro-environmental quality and human health. Photocatalysis using novel engineered nanomaterials such as ZnO nanowires may be promising for removing antibiotics from waters. However, much remains to be learned about efficiency and mechanism for photocatalytic degradation of antibiotics by ZnO nanowires. This study systematically investigated photodegradation of cephalexin using ZnO nanowires under simulated sunlight. The degradation efficiency of cephalexin was substantially increased in the presence of ZnO nanowires especially at circumneutral and alkaline condition (solution pH of 7.2-9.2). The photodegradation followed the first-order kinetics with degradation rate constants (k) ranging between 1.19 × 10-1 and 2.52 × 10-1 min-1 at 20-80 mg L-1 ZnO nanowires. Radical trapping experiments demonstrated that hydroxyl radicals (OH) and superoxide radicals (O2-) predominantly contributed to the removal of cephalexin. With the addition of HCO3- (1-5 mM) or Suwannee River natural organic matter (SRNOM, 2-10 mg L-1), the k values were substantially decreased by a factor of 1.8-70 to 1.69 × 10-3-6.67 × 10-2 min-1, probably due to screening effect of HCO3- or SRNOM sorbed on ZnO nanowires and scavenging of free radicals by free HCO3- or SRNOM in solution. Combining product identification by mass spectrometry and molecular computation, cephalexin photodegradation pathways were identified, including hydroxylation, demethylation, decarboxylation, and dealkylation. Overall, the novel ZnO nanowires have the potential to be used for removing antibiotics from contaminated waters.


Assuntos
Antibacterianos/química , Cefalexina/química , Nanofios/química , Luz Solar , Poluentes Químicos da Água/química , Purificação da Água/métodos , Óxido de Zinco/química , Catálise , Cinética , Nanofios/efeitos da radiação , Fotólise , Rios , Óxido de Zinco/efeitos da radiação
20.
Nanoscale ; 11(33): 15596-15604, 2019 Sep 07.
Artigo em Inglês | MEDLINE | ID: mdl-31403638

RESUMO

The fundamental unit of the nervous system is a synapse, which is involved in transmitting information between neurons as well as learning, memory, and forgetting processes. Two-terminal memristors can fulfil most of these requirements; however, their poor dynamic changes in resistance to input electric stimuli remain an obstacle, which must be improved for accurate and quick information processing. Herein, we demonstrate the synaptic properties of ZnO-based memristors, which were significantly enhanced (∼340 times) by geometrical modulation due to the localized electric field enhancement. Specifically, by inserting Ag-nanowires and Ag-dots into the ZnO/Si interface, the resistive switching could be controlled from a digital to analog mode. A finite element simulation revealed that the presence of Ag could enhance the localized electric field, which in turn improved the migration of ionic species. Further, the device showed a variety of comprehensive synaptic functions, for instance, paired-pulse facilitation and transformation from short-term plasticity to long-term plasticity, including the Pavlovian associative learning process in a human brain. Our study presents a novel architecture to enhance the synaptic sensitivity, and its uses in practical applications, including the artificial learning algorithm.


Assuntos
Algoritmos , Eletricidade , Nanofios/química , Silício/química , Prata/química , Sinapses/fisiologia , Óxido de Zinco/química
SELEÇÃO DE REFERÊNCIAS
DETALHE DA PESQUISA