RESUMO
Applications of asymmetrical flow field-flow fractionation (AF4) continue to expand rapidly in the fields of nanotechnology and biotechnology. In particular, AF4 has proven valuable for the separation and analysis of particles, biomolecular species (e.g., proteins, bacteria) and polymers (natural and synthetic), ranging in size from a few nanometers to several micrometers. The separation of non-spheroidal structures (e.g., rods, tubes, etc.) with primary dimensions in the nanometer regime, is a particularly challenging application deserving of greater study and consideration. The goal of the present study was to advance current understanding of the mechanism of separation of rod-like nano-objects in the AF4 channel. To achieve this, we have systematically investigated a series of commercially available cetyltrimethylammonium bromide stabilized gold nanorods (AuNRs), with aspect ratios from 1.7 to 10. Results show clearly that the retention time is principally dependent on the translational diffusion coefficient of the AuNRs. Equations used to calculate translational and rotational diffusion coefficients (cylinder and prolate ellipsoid models) yield similarly good fits to experimental data. Well characterized gold nanorods (length and diameter by transmission electron microscopy) can be used as calibrants for AF4 measurements allowing one to determine the aspect ratio of nanorod samples based on their retention times. Graphical abstract á .
Assuntos
Fracionamento por Campo e Fluxo/métodos , Ouro/química , Nanotubos/química , Cetrimônio , Compostos de Cetrimônio/química , Difusão , Hidrodinâmica , Nanotubos/ultraestrutura , Tamanho da PartículaRESUMO
Zinc oxide nanomaterials (ZnO NM) have been used in a large number of applications due to their interesting physicochemical properties. However, the increasing use of ZnO NM has led to concerns regarding their environmental impacts. In this study, the acute and chronic toxicity of ZnO nanorods (NR) bare (ZnONR) and amine-functionalized (ZnONR@AF) toward the freshwater microcrustacean Daphnia magna was evaluated. The ZnO NR were characterized by transmission electron microscopy (TEM), X-Ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), and the zeta potential and hydrodynamic diameter (HD). The acute EC50(48h) values for D. magna revealed that the ZnONR@AF were more toxic than the ZnONR. The generation of reactive oxygen species (ROS) was observed in both NM. Regarding the chronic toxicity, the ZnONR@AF were again found to be more toxic than the ZnONR toward D. magna. An effect on longevity was observed for ZnONR, while ZnONR@AF affected the reproduction, growth and longevity. In the multigenerational recovery test, we observed that maternal exposure can affect the offspring even when these organisms are not directly exposed to the ZnO NR.
Assuntos
Aminas/química , Daphnia/efeitos dos fármacos , Nanotubos/toxicidade , Testes de Toxicidade Aguda , Testes de Toxicidade Crônica , Óxido de Zinco/toxicidade , Animais , Hidrodinâmica , Concentração de Íons de Hidrogênio , Nanotubos/ultraestrutura , Espécies Reativas de Oxigênio/metabolismo , Espectroscopia de Infravermelho com Transformada de Fourier , Eletricidade Estática , Poluentes Químicos da Água/toxicidade , Difração de Raios XRESUMO
Dual-functional cupric oxide nanorods (CuONRs) as peroxidase mimics are proposed for the development of a flow-through, label-free chemiluminescent (CL) immunosensor. Forming the basis of this cost-efficient, label-free immunoassay, CuONRs, synthesized using a simple hydrothermal method, were deposited onto epoxy-activated standard glass slides, followed by immobilization of biotinylated capture antibodies through a streptavidin bridge. The CuONRs possess excellent catalytic activity, along with high stability as a solid support. Antigens could then be introduced to the sensing system, forming large immunocomplexes that prevent CL substrate access to the surface, thereby reducing the CL signal in a concentration dependent fashion. Using carcinoembryonic antigen (CEA) as a model analyte, the proposed label-free immunosensor was able to rapidly determine CEA with a wide linear range of 0.1-60ngmL-1 and a low detection limit of 0.05ngmL-1. This nanozyme-based immunosensor is simple, sensitive, cost-efficient, and has the potential to be a very promising platform for fast and efficient biosensing applications.
Assuntos
Anticorpos Imobilizados/química , Materiais Biomiméticos/química , Técnicas Biossensoriais/métodos , Antígeno Carcinoembrionário/sangue , Cobre/química , Nanotubos/química , Peroxidase/química , Biomimética/economia , Biomimética/métodos , Técnicas Biossensoriais/economia , Humanos , Imunoensaio/economia , Imunoensaio/métodos , Limite de Detecção , Medições Luminescentes/economia , Medições Luminescentes/métodos , Nanotubos/ultraestruturaRESUMO
The development of highly sensitive and low-cost methods for detecting DNA is of critical importance. Here, we describe a strategy for the highly sensitive and low-cost digital detection of target DNA. Individual DNA molecules were encoded with a single gold nanorod (Au NR), which was then separated and enriched using the magnetic immune-separation process, followed by dehybridization and dispersion into a buffer solution and immobilization on glass slides for polarized dark-field microscopic imaging. With the imaging we can get the first three data sets of the Stokes vector, and the experimental degree of the linear polarization of the light scattered by the Au NR was obtained. Using the Monte Carlo simulation program, the Muller matrix of the Au NRs was simulated and the simulated degree of the linear polarization was calculated to be 0.58. Based on the experimental and simulated degree of the linear polarization, the Au NRs were identified and quantified with an in-house Matlab program, and the concentration of the target DNA at the femtomolar level was therefore achieved.
Assuntos
DNA Viral/análise , Ouro , Vírus da Hepatite B/genética , Luz , Nanotubos , Espalhamento de Radiação , Sondas de DNA , Microscopia Eletrônica de Varredura , Método de Monte Carlo , Nanotubos/ultraestrutura , Software , Ressonância de Plasmônio de SuperfícieRESUMO
Lipid membrane nanotubes are abundant in living cells, even though tubules are energetically less stable than sheet-like structures. According to membrane elastic theory, the tubular endoplasmic reticulum (ER), with its high area-to-volume ratio, appears to be particularly unstable. We explore how tubular membrane structures can nevertheless be induced and why they persist. In Monte Carlo simulations of a fluid-elastic membrane model subject to thermal fluctuations and without constraints on symmetry, we find that a steady increase in the area-to-volume ratio readily induces tubular structures. In simulations mimicking the ER wrapped around the cell nucleus, tubules emerge naturally as the membrane area increases. Once formed, a high energy barrier separates tubules from the thermodynamically favored sheet-like membrane structures. Remarkably, this barrier persists even at large area-to-volume ratios, protecting tubules against shape transformations despite enormous driving forces toward sheet-like structures. Molecular dynamics simulations of a molecular membrane model confirm the metastability of tubular structures. Volume reduction by osmotic regulation and membrane area growth by lipid production and by fusion of small vesicles emerge as powerful factors in the induction and stabilization of tubular membrane structures.
Assuntos
Lipídeos de Membrana/química , Nanotubos/química , Simulação de Dinâmica Molecular , Método de Monte Carlo , Nanotecnologia/métodos , Nanotubos/ultraestrutura , TermodinâmicaRESUMO
The biopolymer DNA allows to create nanoscale, biocompatible structures, which can be designed in a target-specific and stimuli-responsive manner. DNA carrier systems with these characteristics hold a great potential for nanomedical applications, such as for the treatment of inflammatory diseases. Here we used a DNA-based drug carrier system for the pH-dependent delivery of the glucocorticoid dexamethasone into macrophages, a cell type with a key role in the regulation of inflammation. Dexamethasone (Dex) nanotubes were internalized within minutes by MH-S macrophages in vitro and by tissue resident macrophages in the mouse cremaster muscle in vivo and localized in their endosomes. Treatment with Dex nanotubes in vitro significantly reduced the LPS-induced TNF secretion by macrophages, as compared to equivalent amounts of free dexamethasone without affecting cell viability. Microinjection of Dex nanotubes into postischemic muscle tissue of anesthetized mice resulted in a marked reduction of ischemia-reperfusion-elicited leukocyte transmigration and diminished vascular expression of the endothelial adhesion molecules VCAM-1 and ICAM-1. Taken together, our results demonstrate that DNA nanotubes can be used as a platform for the targeted delivery of glucocorticoids and could thus foster the development of nanomedical therapeutics with reduced off-target effects.
Assuntos
DNA/química , Dexametasona/química , Nanotubos/química , Animais , Anti-Inflamatórios/química , Anti-Inflamatórios/uso terapêutico , Dexametasona/uso terapêutico , Imuno-Histoquímica , Inflamação/tratamento farmacológico , Macrófagos/efeitos dos fármacos , Macrófagos/metabolismo , Masculino , Camundongos , Camundongos Endogâmicos C57BL , Microscopia Eletrônica de Transmissão , Nanotecnologia/métodos , Nanotubos/ultraestrutura , Fator de Necrose Tumoral alfa/metabolismoRESUMO
Receptor coated resonant nanoparticles and quantum dots are proposed to provide a cellular-level resolution image of neural activities inside the brain. The functionalized nanoparticles and quantum dots in this approach will selectively bind to different neurotransmitters in the extra-synaptic regions of neurons. This allows us to detect neural activities in real time by monitoring the nanoparticles and quantum dots optically. Gold nanoparticles (GNPs) with two different geometries (sphere and rod) and quantum dots (QDs) with different sizes were studied along with three different neurotransmitters: dopamine, gamma-Aminobutyric acid (GABA), and glycine. The absorption/emission spectra of GNPs and QDs before and after binding of neurotransmitters and their corresponding receptors are reported. The results using QDs and nanorods with diameter 25nm and aspect rations larger than three were promising for the development of the proposed functional brain mapping approach.
Assuntos
Mapeamento Encefálico/métodos , Neurotransmissores/metabolismo , Animais , Sistemas Computacionais , Dopamina/metabolismo , Glicina/metabolismo , Ouro , Humanos , Nanopartículas Metálicas/ultraestrutura , Microscopia Eletrônica de Transmissão , Modelos Neurológicos , Nanotubos/ultraestrutura , Pontos Quânticos/ultraestrutura , Receptores de Neurotransmissores/metabolismo , Espectrofotometria , Ácido gama-Aminobutírico/metabolismoRESUMO
The flexible and low-cost polypyrrole nanotube membrane is demonstrated as a promising anode in microbial fuel cells, which significantly enhances the extracellular electron transfer between Shewanella oneidensis MR-1 and the electrode, owing to the large active surface area and high electrical conductivity.
Assuntos
Fontes de Energia Bioelétrica/microbiologia , Eletrodos/microbiologia , Transferência de Energia , Membranas Artificiais , Nanotubos/química , Polímeros/química , Pirróis/química , Módulo de Elasticidade , Condutividade Elétrica , Desenho de Equipamento , Análise de Falha de Equipamento , Nanotubos/ultraestruturaRESUMO
The ability to quantitatively and noninvasively detect nanoparticles nearby the skin surface has important implications on their development as an in vivo cancer diagnostic tool. The diffusion reflection (DR) method is a simple, noninvasive imaging technique which has been proven useful for the investigation of the optical parameters of the tissue. A new method is presented for the measurements of gold nanorod (GNR) concentration in tissue-like phantoms, based on DR measurement and intense light absorption of GNR. Monte Carlo simulations and tissue-like phantom measurements of the reflected light intensity are presented. The ability to extract optical properties of phantoms and their GNR concentrations from DR measurements is demonstrated, followed by a discussion about the best mathematical model for light propagation in tissues, based on the diffusion theory.
Assuntos
Meios de Contraste/química , Nanopartículas Metálicas/química , Nanopartículas Metálicas/ultraestrutura , Imagem Molecular/métodos , Nanotubos/química , Nanotubos/ultraestrutura , Neoplasias Cutâneas/diagnóstico , Animais , Linhagem Celular Tumoral , Ouro , Humanos , Camundongos , Camundongos Nus , Modelos Biológicos , Método de Monte Carlo , Fenômenos Ópticos , Imagens de Fantasmas , Tela Subcutânea/patologia , Transplante HeterólogoRESUMO
In this work the hysteretic properties of single wall ferromagnetic nanotubes were studied. Hysteresis loops were computed on the basis of a classical Heisenberg model involving nearest neighbor interactions and using a Monte Carlo method implemented with a single spin movement Metropolis dynamics. Nanotubes with square and hexagonal unit cells were studied varying their diameter, temperature and magneto-crystalline anisotropy. Effects of the diameter were found stronger in the square unit cell magnetic nanotubes (SMNTs) than in the hexagonal unit cell magnetic nanotubes (HMNTs). The ferromagnetic behavior was observed in SMNTs at higher temperature than in HMNTs. Moreover in both cases, SMNTs and HMNTs, the magneto-crystalline anisotropy in the longitudinal direction showed a linear correspondence with the coercive field.
Assuntos
Modelos Teóricos , Nanotubos/química , Nanotubos/ultraestrutura , Simulação por Computador , Campos Magnéticos , Imãs , Teste de Materiais , Método de Monte Carlo , Dinâmica não Linear , Tamanho da Partícula , Espalhamento de RadiaçãoRESUMO
Using a Markov chain approach we rederive the exact density functional for hard-rod mixtures on a one-dimensional lattice, which forms the basis of the lattice fundamental measure theory. The transition probability in the Markov chain depends on a set of occupation numbers, which reflects the property of a zero-dimensional cavity to hold at most one particle. For given mean occupation numbers (density profile), an exact expression for the equilibrium distribution of microstates is obtained, which means an expression for the unique external potential that generates the density profile in equilibrium. By considering the rod ends to fall onto lattice sites, the mixture is always additive.
Assuntos
Misturas Complexas/química , Cadeias de Markov , Modelos Químicos , Modelos Moleculares , Modelos Estatísticos , Nanotubos/química , Nanotubos/ultraestrutura , Coloides/química , Simulação por ComputadorRESUMO
This paper describes a novel on-chip microarray platform based on an electrochemiluminescence resonance energy transfer (ECL-RET) strategy for rapid assay of cancer cell surface biomarkers. This platform consists of 64 antigen-decorated CdS nanorod spots with the diameter of 1.0 cm uniformly distributed on 16 indium tin oxide (ITO) strips, which is coated with a multichannel decorated polydimethylsiloxane (PDMS) slice to realize multiplexed determination of antigens. To shorten the immune reaction time in the microchannels and simplify the device, magnetic stirring and four-channel universal serial bus (USB) ports for plug-and-play were used. When Ru(bpy)(3)(2+) labeled antibodies were selectively captured by the corresponding antigens on the CdS nanorod spot array, ECL-RET from the CdS nanorod (donor) by cathodic emission in the presence of K(2)S(2)O(8) to Ru(bpy)(3)(2+) (acceptor) occurred. With signal amplification of Ru(bpy)(3)(2+) and competitive immunoassay, carcinoembryonic antigen (CEA), α-fetoprotein (AFP), and prostate specific antigen (PSA) as models were detected on this microfluidic device via recording the increased ECL-RET signals on electrode surfaces. Furthermore, this multiplexed competitive immunoassay was successfully used for detecting cancer cell surface antigens via the specific antibody-cell interactions and cell counting via cell surface receptors and antigens on the CdS nanorod surface. This platform provides a rapid and simple but sensitive approach with microliter-level sample volume and holds great promise for multiplexed detection of antigens and antigen-specific cells.
Assuntos
Antígeno Carcinoembrionário/análise , Imunoensaio/instrumentação , Dispositivos Lab-On-A-Chip , Antígeno Prostático Específico/análise , alfa-Fetoproteínas/análise , Anticorpos/química , Anticorpos/imunologia , Compostos de Cádmio/química , Antígeno Carcinoembrionário/imunologia , Linhagem Celular Tumoral , Técnicas Eletroquímicas/economia , Técnicas Eletroquímicas/instrumentação , Eletrodos , Desenho de Equipamento , Humanos , Imunoensaio/economia , Medições Luminescentes/economia , Medições Luminescentes/instrumentação , Masculino , Nanotubos/química , Nanotubos/ultraestrutura , Neoplasias/diagnóstico , Antígeno Prostático Específico/imunologia , Sensibilidade e Especificidade , Sulfetos/química , alfa-Fetoproteínas/imunologiaRESUMO
We report a simple confined self-assembly process to synthesize nanoporous one-dimensional photoactive nanostructures. Through surfactant-assisted cooperative interactions (e.g., π-π stacking, ligand coordination, and so forth) of the macrocyclic building block, zinc meso-tetra (4-pyridyl) porphyrin (ZnTPyP), self-assembled ZnTPyP nanowires and nanorods with controlled diameters and aspect ratios are prepared. Electron microscopy characterization in combination with X-ray diffraction and gas sorption experiments indicate that these materials exhibit stable single-crystalline and high surface area nanoporous frameworks with well-defined external morphology. Optical characterizations using UV-vis spectroscopy and fluorescence imaging and spectroscopy show enhanced collective optical properties over the individual chromophores (ZnTPyP), favorable for exciton formation and transport.
Assuntos
Nanotecnologia/métodos , Nanotubos/química , Nanofios/química , Porfirinas/química , Zinco/química , Nanotecnologia/economia , Nanotubos/ultraestrutura , Nanofios/ultraestrutura , Porosidade , Análise Espectral , Tensoativos/químicaRESUMO
Mondispersed submicrometer GdPO(4):Eu(3+) hollow spheres were synthesized via an effective one-pot hydrothermal process. These hollow spheres have the average diameter of 200 nm, and the shell thickness is about 20 nm. The surface of the spheres consists of a number of nanorods with diameters of about 10 nm and lengths of about 50-80 nm. Both magnetic and luminescent properties of the obtained Eu(3+)-doped GdPO(4) hollow spheres were investigated. The hysteresis plot (M-H) analysis result indicates their paramagnetic property. The fluorescence spectra demonstrate that they emit orange-red color light originated from the (5)D(0) â (7)F(J) transitions of the Eu(3+) ions. Therefore, the obtained GdPO(4) hollow spheres hold promise for encapsulate drugs with controlled release. Moreover, the GdPO(4):Eu(3+) hollow spheres are attributes for bimodal magnetic resonance imaging (MRI)/optical bioimaging labeling.
Assuntos
Preparações de Ação Retardada/síntese química , Portadores de Fármacos/síntese química , Imageamento por Ressonância Magnética/métodos , Nanotecnologia/métodos , Preparações de Ação Retardada/análise , Portadores de Fármacos/análise , Európio/química , Gadolínio/química , Humanos , Luminescência , Magnetismo , Microscopia Eletrônica de Varredura , Microesferas , Imagem Molecular/métodos , Nanotubos/química , Nanotubos/ultraestrutura , Tamanho da Partícula , Porosidade , Espectrometria de FluorescênciaRESUMO
Self-organized TiO(2) nanotube (NT) arrays were produced by anodization in ethylene glycol (EG) electrolytes containing 1-n-butyl-3-methyl-imidazolium tetrafluoroborate (BMI.BF(4)) ionic liquid and water. The morphology of the as-formed NTs was considerably affected by changing the anodization time, voltage, and water and ionic liquid electrolyte concentrations. In general, a nanoporous layer was formed on the top surface of the TiO(2) NTs, except for anodization at 100 V with 1 vol % of BMI.BF(4), where the NT's mouth was revealed. The length and bottom diameter of the NTs as well as the pore diameter of the top layer showed a linear relationship with increased anodization voltage. These TiO(2) NTs were tested as photocatalysts for methyl orange photodegradation and hydrogen evolution from water/methanol solutions by UV light irradiation. The results show that the TiO(2) NTs obtained by anodization in EG/H(2)O/BMI.BF(4) electrolytes are active and efficient for both applications.
Assuntos
Nanotubos/química , Titânio , Compostos Azo/metabolismo , Hidrogênio/metabolismo , Líquidos Iônicos , Nanotubos/ultraestrutura , Processos FotoquímicosRESUMO
With a view to investigate the structural, electronic and magnetic properties of Ni (5%) doped SnO(2) diluted magnetic semiconductor nanorods prepared by a PEG-6000 assisted wet chemical route, a systematic investigation has been carried out. The micro structural properties were investigated by Rietveld refinement of XRD data, AFM, TEM, EDS, SAED, FTIR, Raman scattering and XPS measurements. These studies revealed that Sn0.95Ni0.05O2 nanorods have a polycrystalline single phase tetragonal rutile structure without any detectable impurity phases and the aspect ratios of the nanorods are in the range 2.85-10.2. The deconvoluted XPS core level Ni 2p spectral studies determined the oxidation state of Ni as +2. The nanosize effects and local defects are found to influence the local electronic structure of materials. From M-H, M-T, magnetic force microscopy (MFM) and ESR studies, all the samples are found to exhibit clear room temperature ferromagnetism without any metallic clusters. The magnetization behaviour is found to depend on the overlap of percolated bound magnetic polarons and their interactions with dopant induced defects. The magnetic exchange interactions are found to depend on the aggregation behaviour of nanorods, exchange media, the surface diffusion behaviour of randomly distributed Ni ions and the modification of electronic structure.
Assuntos
Magnetismo , Nanotubos/química , Níquel/química , Compostos de Estanho/química , Nanotubos/ultraestrutura , Espectroscopia Fotoeletrônica , Polietilenoglicóis/química , Temperatura , TermogravimetriaRESUMO
This study presents a large-scale synthesis of water-soluble sodium fluosilicate (Na(2)SiF(6)) nanowires, which serve as a versatile template for producing nanotubes.
Assuntos
Fluoretos/química , Nanotecnologia/métodos , Nanotubos/química , Nanofios/química , Ácido Silícico/química , Fluoretos/síntese química , Nanotecnologia/economia , Nanotubos/ultraestrutura , Nanofios/ultraestrutura , Ácido Silícico/síntese química , Água/químicaAssuntos
Toxinas Bacterianas/análise , Monitoramento Ambiental/métodos , Ouro/química , Microcistinas/análise , Nanotubos/química , Anticorpos/imunologia , Toxinas Bacterianas/imunologia , Monitoramento Ambiental/economia , Imunoensaio/economia , Imunoensaio/métodos , Microcistinas/imunologia , Nanotubos/ultraestrutura , Sensibilidade e EspecificidadeRESUMO
AIMS: The recent development of 1D barcode arrays has proved their capabilities to be applicable to highly multiplexed bioassays. This article introduces two magnetic decoding protocols for suspension arrays of shape-coded silica nanotubes to process multiplexed assays rapidly and easily, which will benefit the minimization and automation of the arrays. METHODS: In the first protocol, the magnetic nanocrystals are incorporated into the inner voids of barcoded silica nanotubes in order to give the nanotubes magnetic properties. The second protocol is performed by trapping the barcoded silica nanotubes onto streptavidin-modified magnetic beads. RESULTS: The rapid and easy decoding process was demonstrated by applying the above two protocols to multiplexed assays, resulting in high selectivity. Furthermore, the magnetic bead-trapped barcode nanotubes provided a great opportunity to exclude the use of dye molecules in multiplexed assays by using barcode nanotubes as signals. CONCLUSION: The rapid and easy manipulation of encoded carriers using magnetic properties could be used to develop promising suspension arrays for portable bioassays.
Assuntos
Técnicas Biossensoriais/métodos , Magnetismo , Nanotubos/química , Proteínas/análise , Dióxido de Silício/química , Animais , Automação , Técnicas Biossensoriais/economia , Antígeno Carcinoembrionário/análise , Humanos , Nanopartículas/química , Nanotubos/ultraestrutura , Sensibilidade e Especificidade , Fatores de TempoRESUMO
Polyaniline (PANI) "sunflowers" made of arrays of oriented nanorods were synthesized by chemical oxidative polymerization of aniline in the presence of cetyltrimethylammonium bromide (CTAB) and suitable concentration of HNO3 at about 0 degrees C (ice bath). The reaction conditions, such as the concentration of reagents and reaction temperature were systematically investigated and controlled on the preparation of PANI "sunflowers". The results also suggest that HNO3 probably plays a key role in forming PANI "sunflowers". A possible forming mechanism of the PANI nanostructures is offered.