31 research outputs found
In situ photothermal response of single gold nanoparticles through hyperspectral imaging anti-stokes thermometry
Several fields of applications require a reliable characterization of the photothermal response and heat dissipation of nanoscopic systems, which remains a challenging task for both modeling and experimental measurements. Here, we present an implementation of anti-Stokes thermometry that enables the in situ photothermal characterization of individual nanoparticles (NPs) from a single hyperspectral photoluminescence confocal image. The method is label-free, potentially applicable to any NP with detectable anti-Stokes emission, and does not require any prior information about the NP itself or the surrounding media. With it, we first studied the photothermal response of spherical gold NPs of different sizes on glass substrates, immersed in water, and found that heat dissipation is mainly dominated by the water for NPs larger than 50 nm. Then, the role of the substrate was studied by comparing the photothermal response of 80 nm gold NPs on glass with sapphire and graphene, two materials with high thermal conductivity. For a given irradiance level, the NPs reach temperatures 18% lower on sapphire and 24% higher on graphene than on bare glass. The fact that the presence of a highly conductive material such as graphene leads to a poorer thermal dissipation demonstrates that interfacial thermal resistances play a very significant role in nanoscopic systems and emphasize the need for in situ experimental thermometry techniques. The developed method will allow addressing several open questions about the role of temperature in plasmon-assisted applications, especially ones where NPs of arbitrary shapes are present in complex matrixes and environments
DNA-based Self-Assembly of Chiral Plasmonic Nanostructures with Tailored Optical Response
Surface plasmon resonances generated in metallic nanostructures can be
utilized to tailor electromagnetic fields. The precise spatial arrangement of
such structures can result in surprising optical properties that are not found
in any naturally occurring material. Here, the designed activity emerges from
collective effects of singular components equipped with limited individual
functionality. Top-down fabrication of plasmonic materials with a predesigned
optical response in the visible range by conventional lithographic methods has
remained challenging due to their limited resolution, the complexity of
scaling, and the difficulty to extend these techniques to three-dimensional
architectures. Molecular self-assembly provides an alternative route to create
such materials which is not bound by the above limitations. We demonstrate how
the DNA origami method can be used to produce plasmonic materials with a
tailored optical response at visible wavelengths. Harnessing the assembly power
of 3D DNA origami, we arranged metal nanoparticles with a spatial accuracy of 2
nm into nanoscale helices. The helical structures assemble in solution in a
massively parallel fashion and with near quantitative yields. As a designed
optical response, we generated giant circular dichroism and optical rotary
dispersion in the visible range that originates from the collective
plasmon-plasmon interactions within the nanohelices. We also show that the
optical response can be tuned through the visible spectrum by changing the
composition of the metal nanoparticles. The observed effects are independent of
the direction of the incident light and can be switched by design between left-
and right-handed orientation. Our work demonstrates the production of complex
bulk materials from precisely designed nanoscopic assemblies and highlights the
potential of DNA self-assembly for the fabrication of plasmonic nanostructures.Comment: 5 pages, 4 figure
Rhodium nanoparticles for ultraviolet plasmonics
The nonoxidizing catalytic noble metal rhodium is introduced for ultraviolet plasmonics. Planar tripods of 8 nm Rh nanoparticles, synthesized by a modified polyol reduction method, have a calculated local surface plasmon resonance near 330 nm. By attaching p-aminothiophenol, local field-enhanced Raman spectra and accelerated photodamage were observed under near-resonant ultraviolet illumination, while charge transfer simultaneously increased fluorescence for up to 13 min. The combined local field enhancement and charge transfer demonstrate essential steps toward plasmonically enhanced ultraviolet photocatalysis.This work has
been supported by NSF-ECCS-12-32239. This work was
partially supported by the Army’s In-house Laboratory
Innovative Research program. Financial support from USAITCA
(project no. W911NF-13-1-0245) and MICINN (Spanish
Ministry of Science and Innovation, project no. FIS2013-
45854-P) is also acknowledged
Surface-Enhanced Raman Scattering Plasmonic Enhancement Using DNA Origami-Based Complex Metallic Nanostructures
DNA
origami is a novel self-assembly technique allowing one to form various
two-dimensional shapes and position matter with nanometer accuracy.
We use DNA origami templates to engineer surface-enhanced Raman scattering
substrates. Specifically, gold nanoparticles were selectively placed
on the corners of rectangular origami and subsequently enlarged via
solution-based metal deposition. The resulting assemblies exhibit
“hot spots” of enhanced electromagnetic field between
the nanoparticles. We observed a significant Raman signal enhancement
from molecules covalently attached to the assemblies, as compared
to control nanoparticle samples that lack interparticle hot spots.
Furthermore, Raman molecules are used to map out the hot spots’
distribution, as they are burned when experiencing a threshold electric
field. Our method opens up the prospects of using DNA origami to rationally
engineer and assemble plasmonic structures for molecular spectroscopy
Surface-Enhanced Raman Scattering Plasmonic Enhancement Using DNA Origami-Based Complex Metallic Nanostructures
DNA
origami is a novel self-assembly technique allowing one to form various
two-dimensional shapes and position matter with nanometer accuracy.
We use DNA origami templates to engineer surface-enhanced Raman scattering
substrates. Specifically, gold nanoparticles were selectively placed
on the corners of rectangular origami and subsequently enlarged via
solution-based metal deposition. The resulting assemblies exhibit
“hot spots” of enhanced electromagnetic field between
the nanoparticles. We observed a significant Raman signal enhancement
from molecules covalently attached to the assemblies, as compared
to control nanoparticle samples that lack interparticle hot spots.
Furthermore, Raman molecules are used to map out the hot spots’
distribution, as they are burned when experiencing a threshold electric
field. Our method opens up the prospects of using DNA origami to rationally
engineer and assemble plasmonic structures for molecular spectroscopy
DNA-Templated Ultracompact Optical Antennas for Unidirectional Single-Molecule Emission
Optical antennas are nanostructures designed to manipulate light-matter interactions by interfacing propagating light with localized optical fields. In recent years, numerous devices have been realized to efficiently tailor the absorption and/or emission rates of fluorophores. By contrast, modifying the spatial characteristics of their radiation fields remains challenging. Successful phased array nanoantenna designs have required the organization of several elements over a footprint comparable to the operating wavelength. Here, we report unidirectional emission of a single fluorophore using an ultracompact optical antenna. The design consists of two side-by-side gold nanorods self-assembled via DNA origami, which also controls the positioning of the single-fluorophore. Our results show that when a single fluorescent molecule is positioned at the tip of one nanorod and emits at a frequency capable of driving the antenna in the antiphase mode, unidirectional emission with a forward to backward ratio of up to 9.9 dB can be achieved.Fil: Zhu, Fangjia. Universite de Fribourg;Fil: Sanz Paz, María. Universite de Fribourg;Fil: Fernández Domínguez, Antonio I.. Universidad Autónoma de Madrid; EspañaFil: Zhuo, Xiaolu. Centro de Investigación Cooperativa en Biomateriales; EspañaFil: Liz Marzán, Luis M. Centro de Investigación Cooperativa en Biomateriales; EspañaFil: Stefani, Fernando Daniel. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Parque Centenario. Centro de Investigaciones en Bionanociencias "Elizabeth Jares Erijman"; ArgentinaFil: Pilo Pais, Mauricio. Universite de Fribourg;Fil: Acuna, Guillermo P.. Universite de Fribourg
Three-dimensional total-internal reflection fluorescence nanoscopy with nanometric axial resolution by photometric localization of single molecules
Single-molecule localization microscopy enables far-field imaging with lateral resolution in the range of 10 to 20 nanometres, exploiting the fact that the centre position of a single-molecule’s image can be determined with much higher accuracy than the size of that image itself. However, attaining the same level of resolution in the axial (third) dimension remains challenging. Here, we present Supercritical Illumination Microscopy Photometric z-Localization with Enhanced Resolution (SIMPLER), a photometric method to decode the axial position of single molecules in a total internal reflection fluorescence microscope. SIMPLER requires no hardware modification whatsoever to a conventional total internal reflection fluorescence microscope and complements any 2D single-molecule localization microscopy method to deliver 3D images with nearly isotropic nanometric resolution. Performance examples include SIMPLER-direct stochastic optical reconstruction microscopy images of the nuclear pore complex with sub-20 nm axial localization precision and visualization of microtubule cross-sections through SIMPLER-DNA points accumulation for imaging in nanoscale topography with sub-10 nm axial localization precision.Fil: Szalai, Alan Marcelo. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Parque Centenario. Centro de Investigaciones en Bionanociencias "Elizabeth Jares Erijman"; ArgentinaFil: Siarry, Bruno. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Parque Centenario. Centro de Investigaciones en Bionanociencias "Elizabeth Jares Erijman"; ArgentinaFil: Lukin, Jeronimo. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Parque Centenario. Instituto de Investigación en Biomedicina de Buenos Aires - Instituto Partner de la Sociedad Max Planck; ArgentinaFil: Williamson, David J.. King’s College London; Reino UnidoFil: Unsain, Nicolas. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba. Instituto de Investigación Médica Mercedes y Martín Ferreyra. Universidad Nacional de Córdoba. Instituto de Investigación Médica Mercedes y Martín Ferreyra; ArgentinaFil: Caceres, Alfredo Oscar. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba. Instituto de Investigación Médica Mercedes y Martín Ferreyra. Universidad Nacional de Córdoba. Instituto de Investigación Médica Mercedes y Martín Ferreyra; Argentina. Instituto Universitario de Ciencias Biomédicas de Córdoba; ArgentinaFil: Pilo Pais, Mauricio. Universite de Fribourg (unifr);Fil: Acuna, Guillermo. Universite de Fribourg (unifr);Fil: Refojo, Damian. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Parque Centenario. Instituto de Investigación en Biomedicina de Buenos Aires - Instituto Partner de la Sociedad Max Planck; ArgentinaFil: Owen, Dylan M.. King’s College London; Reino Unido. University of Birmingham; Reino UnidoFil: Simoncelli, Sabrina. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Parque Centenario. Centro de Investigaciones en Bionanociencias "Elizabeth Jares Erijman"; Argentina. King’s College London; Reino Unido. University College London; Estados UnidosFil: Stefani, Fernando Daniel. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Parque Centenario. Centro de Investigaciones en Bionanociencias "Elizabeth Jares Erijman"; Argentina. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Departamento de Física; Argentin