Abstract
We report sensing of single nanoparticles using disordered metallic nanoisland substrates supporting surface plasmon polaritons (SPPs). Speckle patterns arising from leakage radiation of elastically scattered SPPs provide a unique fingerprint of the scattering microstructure at the sensor surface. Experimental measurements of the speckle decorrelation are presented and shown to enable detection of sorption of individual gold nanoparticles and polystyrene beads. Our approach is verified through bright-field and fluorescence imaging of particles adhering to the nanoisland substrate.
Highlights
Recent years have seen great progress in the development of micro- and nanoscale optical technologies for biodetection
We report sensing of single nanoparticles using disordered metallic nanoisland substrates supporting surface plasmon polaritons (SPPs)
Upon careful inspection of the bright field images for the frames preceding and following the steps, it is apparent that the B1, B3 and U1 events can be attributed to adsorption and desorption of nanoparticles at the positions indicated in figures 3(a) and (c)
Summary
Recent years have seen great progress in the development of micro- and nanoscale optical technologies for biodetection. Surface plasmon resonance (SPR) sensors, i.e. those based on coupled electronic-optical oscillations at planar metal interfaces, are currently one of the leading commercial technologies as they allow label-free multiplexed sensing, operation in aqueous environments and easy integration with microfluidic technology [5, 6]. Despite their proven record, traditional SPR sensors rely on detecting resonance perturbations, e.g. frequency shifts, caused by analyte induced bulk refractive index changes and are currently not capable of single molecule measurements. Single molecule sensitivity is desirable [7, 8] since it facilitates rapid detection and allows non-equilibrium studies to be performed
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