15 research outputs found
Quantitative LSPR Imaging for Biosensing with Single Nanostructure Resolution
AbstractLocalized surface plasmon resonance (LSPR) imaging has the potential to map complex spatio-temporal variations in analyte concentration, such as those produced by protein secretions from live cells. A fundamental roadblock to the realization of such applications is the challenge of calibrating a nanoscale sensor for quantitative analysis. Here, we introduce a new, to our knowledge, LSPR imaging and analysis technique that enables the calibration of hundreds of individual gold nanostructures in parallel. The calibration allowed us to map the fractional occupancy of surface-bound receptors at individual nanostructures with nanomolar sensitivity and a temporal resolution of 225Â ms. As a demonstration of the techniqueâs applicability to molecular and cell biology, the calibrated array was used for the quantitative LSPR imaging of anti-c-myc antibodies harvested from a cultured 9E10 hybridoma cell line without the need for further purification or processing
Quantification of Efficient Plasmonic Hot-Electron Injection in Gold NanoparticleâTiO<sub>2</sub> Films
Excitation
of localized surface plasmons in metal nanostructures
generates hot electrons that can be transferred to an adjacent semiconductor,
greatly enhancing the potential light-harvesting capabilities of photovoltaic
and photocatalytic devices. Typically, the external quantum efficiency
of these hot-electron devices is too low for practical applications
(<1%), and the physics underlying this low yield remains unclear.
Here, we use transient absorption spectroscopy to quantify the efficiency
of the initial electron transfer in model systems composed of gold
nanoparticles (NPs) fully embedded in TiO<sub>2</sub> or Al<sub>2</sub>O<sub>3</sub> films. In independent experiments, we measure free
carrier absorption and electronâphonon decay in the model systems
and determine that the electron-injection efficiency from the Au NPs
to the TiO<sub>2</sub> ranges from about 25% to 45%. While much higher
than some previous estimates, the measured injection efficiency is
within an upper-bound estimate based on a simple approximation for
the Au hot-electron energy distribution. These results have important
implications for understanding the achievable injection efficiencies
of hot-electron plasmonic devices and show that the injection efficiency
can be high for Au NPs fully embedded within a semiconductor with
dimensions less than the Au electron mean free path