Nanoparticle-Templated Self-Assembly of Viral Capsids Probed by Time-Resolved Absorbance Spectroscopy and X-Ray Scattering

Abstract

Viral capsid proteins have the remarkable ability to self-assemble around a cargo core, whether their genome, a polyelectrolyte or an inorganic nanoparticle. Although the equilibrium properties of such composite objects have been broadly investigated, little is known about the kinetic pathways leading to their assembly. By exploiting the plasmon resonance effect of gold nanoparticles, we show that the adsorption of viral proteins can be monitored through the redshift of the resonance wavelength. Kinetic measurements reveal that the process occurs in less than a second. The spatial arrangement of nanoparticles is probed by time-resolved small-angle X-ray scattering, and we observe the formation of transient aggregates with a lifetime in the hour range. The biocompatibility of gold nanoparticles induced by adsorbed proteins is of great importance for their use in biomedicine and the reported results should help better understand the processes of formation.