Showing papers by "Peter Zijlstra published in 2016"

Strong reduction of spectral heterogeneity in gold bipyramids for single-particle and single-molecule plasmon sensing.

Abstract: Single metal nanoparticles are attractive biomolecular sensors. Binding of analyte to a functional particle results in a plasmon shift that can be conveniently monitored in a far-field optical microscope. Heterogeneities in spectral properties of individual particles in an ensemble affect the reliability of a single-particle plasmon sensor, especially when plasmon shifts are monitored in real-time using a fixed irradiation wavelength. We compare the spectral heterogeneity of different plasmon sensor geometries (gold nanospheres, nanorods, and bipyramids) and correlate this to their size and aspect-ratio dispersion. We show that gold bipyramids exhibit a strongly reduced heterogeneity in aspect ratio and plasmon wavelength compared to commonly used gold nanorods. We show that this translates into a significantly improved homogeneity of the response to molecular binding without compromising single-molecule sensitivity.

Biosensor based on single-molecule fluorescence detection

Abstract: A method for sensing an analyte [502] includes bringing a matrix containing the analyte into contact with a sensor device having a sensing volume containing fluorescent emitters [500] that switch from a first state [504] to a second state [506] when activated by chemical activation by the analyte. The fluorescent emitters are excited with optical radiation [510] to generate fluorescence optical radiation [514]. The excitation induces photo-bleaching of the activated fluorescent emitters, which limits the duration of the generated fluorescence optical radiation. Each resulting pulse of the fluorescence optical radiation is associated with a single one of the fluorescent emitters. The pulses are detected [516] and processed [518] to determine the presence/concentration of the analyte from changes in the detected fluorescence optical radiation.