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1.
Viruses ; 13(7)2021 07 19.
Artigo em Inglês | MEDLINE | ID: mdl-34372606

RESUMO

As demonstrated with the novel coronavirus pandemic, rapid and accurate diagnosis is key to determine the clinical characteristic of a disease and to improve vaccine development. Once the infected person is identified, hematological findings may be used to predict disease outcome and offer the correct treatment. Rapid and accurate diagnosis and clinical parameters are pivotal to track infections during clinical trials and set protection status. This is also applicable for re-emerging diseases like dengue fever, which causes outbreaks in Asia and Latin America every 4 to 5 years. Some areas in the US are also endemic for the transmission of dengue virus (DENV), the causal agent of dengue fever. However, significant number of DENV infections in rural areas are diagnosed solely by clinical and hematological findings because of the lack of availability of ELISA or PCR-based tests or the infrastructure to implement them in the near future. Rapid diagnostic tests (RDT) are a less sensitive, yet they represent a timely way of detecting DENV infections. The purpose of this study was to determine whether there is an association between hematological findings and the probability for an NS1-based DENV RDT to detect the DENV NS1 antigen. We also aimed to describe the hematological parameters that are associated with the diagnosis through each test.


Assuntos
COVID-19/diagnóstico , COVID-19/epidemiologia , Dengue/diagnóstico , Adolescente , Adulto , Ásia/epidemiologia , Criança , Pré-Escolar , Colômbia/epidemiologia , Dengue/virologia , Vírus da Dengue/isolamento & purificação , Testes Diagnósticos de Rotina/métodos , Ensaio de Imunoadsorção Enzimática , Feminino , Humanos , Lactente , Masculino , Pandemias , Reação em Cadeia da Polimerase , Kit de Reagentes para Diagnóstico , SARS-CoV-2/isolamento & purificação , Adulto Jovem
2.
Sci Rep ; 9(1): 16263, 2019 Nov 07.
Artigo em Inglês | MEDLINE | ID: mdl-31700038

RESUMO

We demonstrate the implications of very low voltage operation (<1 kV) of a scanning electron microscope for imaging low-dimensional nanostructures where standard voltages (2-5 kV) involve a beam penetration depth comparable to the cross-section of the nanostructures. In this common situation, image sharpness, contrast quality and resolution are severely limited by emission of secondary electrons far from the primary beam incidence point. Oppositely, very low voltage operation allows reducing the beam-specimen interaction to an extremely narrow and shallow region around the incidence point, enabling high-resolution and ultra-shallow topographic contrast imaging by high-angle backscattered electrons detection on the one hand, and depth-tunable material contrast imaging by low-angle backscattered electrons detection on the other. We describe the performance of these imaging approaches on silicon nanowires obtained by the vapor-liquid-solid mechanism. Our experimental results, supported by Monte Carlo simulations of backscattered electrons emission from the nanowires, reveal the self-assembly of gold-silica core-shell nanostructures at the nanowire tips without any ad-hoc thermal oxidation step. This result demonstrates the capacity of very low voltage operation to provide optimum sharpness, contrast and resolution in low-dimensional nanostructures and to gather information about nanoscaled core-shell conformations otherwise impossible to obtain by standard scanning electron microscopy alone.

3.
Nanomaterials (Basel) ; 9(9)2019 Aug 28.
Artigo em Inglês | MEDLINE | ID: mdl-31466379

RESUMO

Based on an already tested laboratory procedure, a new magnetron sputtering methodology to simultaneously coat two-sides of large area implants (up to ~15 cm2) with Ti nanocolumns in industrial reactors has been developed. By analyzing the required growth conditions in a laboratory setup, a new geometry and methodology have been proposed and tested in a semi-industrial scale reactor. A bone plate (DePuy Synthes) and a pseudo-rectangular bone plate extracted from a patient were coated following the new methodology, obtaining that their osteoblast proliferation efficiency and antibacterial functionality were equivalent to the coatings grown in the laboratory reactor on small areas. In particular, two kinds of experiments were performed: Analysis of bacterial adhesion and biofilm formation, and osteoblasts-bacteria competitive in vitro growth scenarios. In all these cases, the coatings show an opposite behavior toward osteoblast and bacterial proliferation, demonstrating that the proposed methodology represents a valid approach for industrial production and practical application of nanostructured titanium coatings.

4.
PLoS One ; 14(1): e0208455, 2019.
Artigo em Inglês | MEDLINE | ID: mdl-30601814

RESUMO

Dengue virus (DENV) is an arbovirus responsible for a significant number of deaths in Latin America. This virus is transmitted through the bite of Aedes aegypti, the main mosquito vector, and Ae. albopictus. During blood uptake, the mosquito injects its saliva into the host to facilitate the feeding process. Mosquito saliva contains potent immunogens capable of inducing antibody production directly related to mosquito bite exposure intensity and disease risk. In this study, we first determined the DENV infection status by two different DENV non-structural protein 1 (NS1) based rapid tests and qRT-PCR, then measured the levels of IgG1 and IgG4 antibodies against salivary proteins of Ae. aegypti female mosquitoes in volunteers living in a dengue endemic area. Our results show that people with a positive DENV diagnosis present higher levels of IgG4 antibodies than people with a negative diagnostic test, and that these antibody levels were higher in people with secondary DENV infections. With this study, we show that detection of IgG4 antibodies against mosquito saliva may be a reliable method to evaluate the risk of dengue infection.


Assuntos
Aedes/imunologia , Dengue/epidemiologia , Imunoglobulina G/imunologia , Proteínas e Peptídeos Salivares/imunologia , Adolescente , Adulto , Animais , Formação de Anticorpos/imunologia , Antígenos Virais/imunologia , Criança , Pré-Escolar , Colômbia/epidemiologia , Feminino , Humanos , Lactente , Pessoa de Meia-Idade , Fatores de Risco , Glândulas Salivares/metabolismo , Proteínas não Estruturais Virais/metabolismo , Adulto Jovem
5.
Nano Lett ; 14(4): 2079-85, 2014.
Artigo em Inglês | MEDLINE | ID: mdl-24645987

RESUMO

In this work we discuss the excitation of parallel collective resonances in arrays of gold nanoparticles. Parallel collective resonances result from the coupling of the nanoparticles localized surface plasmons with diffraction orders traveling in the direction parallel to the polarization vector. While they provide field enhancement and delocalization as the standard collective resonances, our results suggest that parallel resonances could exhibit greater tolerance to index asymmetry in the environment surrounding the arrays. The near- and far-field properties of these resonances are analyzed, both experimentally and numerically.

6.
Small ; 7(23): 3317-23, 2011 Dec 02.
Artigo em Inglês | MEDLINE | ID: mdl-21972067

RESUMO

A Co nanolayer is used as a local probe to evaluate the vertical inhomogeneous distribution of the electromagnetic (EM) field within a resonant metallic nanodisk. Taking advantage of the direct relation between the magneto-optical activity and the electromagnetic field intensity in the Co layer, it is shown that the nonuniform EM distribution within the nanodisk under plasmon resonant conditions has maximum values close to the upper and lower flat faces, and a minimum value in the middle.


Assuntos
Campos Eletromagnéticos , Metais/química , Nanoestruturas/química , Coloides , Módulo de Elasticidade , Óptica e Fotônica , Ressonância de Plasmônio de Superfície
7.
Nano Lett ; 10(11): 4450-55, 2010 Nov 10.
Artigo em Inglês | MEDLINE | ID: mdl-20957982

RESUMO

We present resonant dielectric structures exhibiting arbitrarily large optical field enhancement, only limited by fabrication imperfections. Three different arrangements are investigated, based upon dielectric waveguides, dielectric particle arrays, and a combination of these two structures. Experimental confirmation of enhancement in a waveguide resonator is achieved by measuring the luminescence of quantum dots dispersed in the hot optical region of the structure. The performance of these systems can be readily controlled by simply changing geometrical parameters, which allows obtaining remarkable values of the intensity enhancement approaching 105 relative to the incident intensity over large volumes under feasible experimental conditions. This opens new avenues for all-optical switching and biosensing.


Assuntos
Medições Luminescentes/instrumentação , Pontos Quânticos , Refratometria/instrumentação , Desenho Assistido por Computador , Desenho de Equipamento , Análise de Falha de Equipamento , Luz , Espalhamento de Radiação
8.
Opt Express ; 18(15): 15635-42, 2010 Jul 19.
Artigo em Inglês | MEDLINE | ID: mdl-20720945

RESUMO

We report that the effect of an external magnetic field on the propagation of surface plasmons can be effectively modified through the coupling between localized (LSP) and propagating (SPP) surface plasmons. When these plasmon modes do not interact, the main effect of the magnetic field is a modification of the wavevector of the SPP mode, leaving the LSP virtually unaffected. Once both modes start to interact, there is a strong variation of the magnetic field induced modification of the SPP dispersion curve and, simultaneously, the LSP mode becomes sensitive to the magnetic field.

9.
ACS Nano ; 3(5): 1231-7, 2009 May 26.
Artigo em Inglês | MEDLINE | ID: mdl-19385661

RESUMO

In this study, we report on ultrasensitive protein detection with lithographically prepared plasmonic nanostructures. We have engineered optical nanosensors by the combined approach of negative resist, electron beam lithography, and reactive ion etching to form highly reproducible arrays of gold dimers in which the near-field coupling in their subwavelength gap enables for scaling the sensing volume down to the single-protein scale. In good agreement with recent theoretical predictions, the dimer geometry offers enhanced sensitivity compared to isolated particles for the detection of both small organic molecules and proteins. Beyond, by exploiting size exclusion, we are capable of monitoring the number of proteins able to bind across the gap region through the precise engineering of the structures coupled to the selective binding of a surface-assembled monolayer and covalent attachment of the protein.


Assuntos
Técnicas Biossensoriais/instrumentação , Ouro/química , Técnicas de Sonda Molecular/instrumentação , Nanoestruturas/química , Nanotecnologia/instrumentação , Análise Serial de Proteínas/instrumentação , Ressonância de Plasmônio de Superfície/instrumentação , Cristalização/métodos , Dimerização , Desenho de Equipamento , Análise de Falha de Equipamento , Substâncias Macromoleculares/química , Conformação Molecular , Nanoestruturas/ultraestrutura , Tamanho da Partícula , Propriedades de Superfície
10.
Opt Express ; 15(17): 10533-9, 2007 Aug 20.
Artigo em Inglês | MEDLINE | ID: mdl-19547406

RESUMO

Efficient transmission of light through a metal layer has become a key issue for a variety of applications including light-emitting diodes and solar cells. We report here on a novel strategy where localized and extended surface plasmons are combined to maximize the fluorescence transmission through a metallic film. We show that the dispersion of an artificial material formed by an array of metal nanoparticles coupled to a flat metal layer can be engineered to make the metal film, in a specific direction, 100% transmissive.

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