RESUMO
This paper reports an all-moldable nanofabrication platform that can generate, from a single master, large-area nanoscale patterns with programmable densities, fill factors, and lattice symmetries. Solvent-assisted nanoscale embossing (SANE) could increase the spacing of patterns up to 100% as well as decrease them down to 50% in a single step by stretching or heating a polymer substrate. Also, SANE could reduce critical feature sizes as small as 45% compared to the master by controlled swelling of patterned molds with different solvents. These capabilities were applied to generate plasmonic nanoparticle arrays with continuously variable separations and hence different optical properties on the same substrate.
Assuntos
Cristalização/métodos , Elastômeros/química , Nanopartículas/química , Nanopartículas/ultraestrutura , Nanotecnologia/métodos , Solventes/química , Ressonância de Plasmônio de Superfície/métodos , Desenho de Equipamento , Análise de Falha de Equipamento , Substâncias Macromoleculares/química , Teste de Materiais , Conformação Molecular , Nanomedicina , Tamanho da Partícula , Refratometria , Propriedades de SuperfícieRESUMO
This paper reports a new type of diffractive microlens based on finite-areas of two-dimensional arrays of circular nanoholes (patches). The plasmonic microlenses can focus single wavelengths of light across the entire visible spectrum as well as broadband white light with little divergence. The focal length is determined primarily by the overall size of the patch and is tolerant to significant changes in patch substructure, including lattice geometry and local order of the circular nanoholes. The optical throughput, however, depends sensitively on the patch substructure and is determined by the wavelengths of surface plasmon resonances. This simple diffractive lens design enables millions of broadband plasmonic microlenses to be fabricated in parallel using soft nanolithographic techniques.
RESUMO
This paper describes three-dimensional (3D) nanohole arrays whose high optical transmission is mediated more by localized surface plasmon (LSP) excitations than by surface plasmon polaritons (SPPs). First, LSPs on 3D hole arrays lead to optical transmission an order of magnitude higher than 2D planar hole arrays. Second, LSP-mediated transmission is broadband and more tunable than SPP-enhanced transmission, which is restricted by Bragg coupling. Third, for the first time, two types of surface plasmons can be selectively excited and manipulated on the same plasmonic substrate. This new plasmonic substrate fabricated by high-throughput nanolithography techniques paves the way for cutting-edge optoelectronic and biomedical applications.
Assuntos
Nanoestruturas , Ressonância de Plasmônio de SuperfícieRESUMO
This paper describes how angle-dependent resonances from molded plasmonic crystals can be used to improve real-time biosensing. First, an inexpensive and massively parallel approach to create single-use, two-dimensional metal nanopyramidal gratings was developed. Second, although constant in bulk dielectric environments, the sensitivities (resonance wavelength shift and resonance width) of plasmonic crystals to adsorbed molecular layers of varying thickness were found to depend on incident excitation angle. Third, protein binding at dilute concentrations of protein was carried out at an angle that optimized the signal to noise of our plasmonic sensing platform. This angle-dependent sensitivity, which is intrinsic to grating-based sensors, is a critical parameter that can assist in maximizing signal to noise.
Assuntos
Arachis/química , Dissacarídeos/metabolismo , Lectinas/metabolismo , Proteínas de Plantas/metabolismo , Ressonância de Plasmônio de Superfície/instrumentação , Dissacarídeos/química , Lectinas/análise , Microtecnologia , Proteínas de Plantas/análise , Ligação Proteica , Sensibilidade e Especificidade , Ressonância de Plasmônio de Superfície/economiaRESUMO
This paper describes the fabrication and characterization of nested Au pyramidal nanoshells. These particles exhibited two plasmon resonances at visible and near-infrared wavelengths that could be manipulated depending on the size of the gap between inner and outer pyramidal shells. We found that larger gaps (30 nm) exhibited much larger Raman scattering responses compared to smaller gaps (5 nm) in the nested pyramidal shells. The SERS-activity of these anisotropic particles can be optimized by adjusting the distances between the inner and outer Au shells.
RESUMO
We demonstrate using nanohole arrays of mixed designs and a microwriting process based on dip-pen nanolithography to monitor multiple, different protein binding events simultaneously in real-time based on the intensity of Extraordinary Optical Transmission of nanohole arrays. The microwriting process and small footprint of the individual nanohole arrays enabled us to observe different binding events located only 16 microm apart, achieving high spatial resolution. We also present a novel concept that incorporates nanohole arrays of different designs to improve confidence and accuracy of binding studies. For proof of concept, two types of nanohole arrays, designed to exhibit opposite responses to protein bindings, were fabricated on one transducer. Initial studies indicate that the mixed designs could help to screen out artifacts such as protein intrinsic signals, providing improved accuracy of binding interpretation.
Assuntos
Microtecnologia/métodos , Nanoestruturas/química , Análise Serial de Proteínas/instrumentação , Proteínas/metabolismo , Desenho de Equipamento , Nanoestruturas/ultraestrutura , Análise Serial de Proteínas/métodos , Ligação Proteica , Proteínas/química , Fatores de TempoRESUMO
We performed multiplexed sensing on nanohole array devices to simultaneously obtain information on molecular absorption, scattering, and refractive-index change, which were distinguished by using different array structures with distinct optical behavior. Up to 25 arrays were fabricated within a 65 microm x 50 microm area to provide real-time information of the local surface environment. The performance of multiplexed sensing was examined by flowing NaCl, Coomassie blue, bovine serum albumin, and liposome solutions that exhibit different visible light absorption/scattering properties and different refractive indices. Experimental artifacts from light source fluctuation, sample injections, and light scattering induced by aggregates in solutions were detected by monitoring superwavelength holes or nanohole arrays with different periodicity and hole diameters.
Assuntos
Iluminação/instrumentação , Nanoestruturas/química , Nanotecnologia/instrumentação , Ressonância de Plasmônio de Superfície/instrumentação , Desenho de Equipamento , Análise de Falha de Equipamento , Nanoestruturas/ultraestrutura , Porosidade , Reprodutibilidade dos Testes , Sensibilidade e EspecificidadeRESUMO
We describe a nanoplasmonic probing platform that exploits small-dimension (Assuntos
Sondas Moleculares
, Nanoestruturas
, Polímeros/química
, Cinética