Direct observation of the orientation dynamics of single protein-coated nanoparticles at liquid/solid interfaces

Abstract

We have observed the rotational dynamics of single protein-coated gold nanorods (AuNRs) on C18-modified silica surfaces in real time by dual-channel polarization dark-field microscopy. Four different rotational states were identified, depending on the apparent strength of interactions between the AuNRs and the surface. The distributions of the states could be regulated by adjusting the salt concentration, and the state transitions were verified by monitoring the entire desorption process of a single AuNR. Our study provides insight into the interfacial orientation and dynamics of nanoparticles and could be useful for in vitro biophysics and the separation of proteins. True affinity or mixed feelings? By the rotational and translational tracking of single protein-coated gold nanorods on C18-modified silica surfaces in real time, four different dynamic states and their transitions were observed. The different states (see picture) reflected spatial and temporal variation of the strength of the hydrophobic interaction between individual probes and the surface. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.