We present in situ studies on the adsorption of proteins to plasmonic nanoparticles. We have implemented luminescence and scattering correlation spectroscopy with single particle sensitivity as an optical tool to quantify changes in the nanoparticle Brownian motion resulting from protein adsorption onto the nanoparticle surface. We are able to measure changes in the hydrodynamic radius of only a few nanometers corresponding to protein monolayer coverages. Nanoparticle aggregation can be distinguished by analyzing the collected photon trajectories for the intensity and number of individual bursts caused by single objects passing through the confocal excitation volume. We also measure adsorption isotherms to elucidate the thermodynamics of protein binding. For an accurate implementation of correlation spectroscopy methods it is furthermore necessary to understand how the collected optical signal scales with nanoparticle size and shape. We are able to obtain this information by correlated electron microscopy and single particle spectroscopy of immobilized plasmonic nanoparticles.

Interactions between plasmonic nanoparticles and proteins investigated by correlation spectroscopy with single particle sensitivity

245th National Meeting (2013)

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