Viral coat proteins as flexible nano-building-blocks for nanoparticle encapsulation.

Viral capsid-nanoparticle hybrid structures offer new opportunities for nanobiotechnology. We previously generated virus-based nanoparticles (VNPs) of simian virus 40 (SV40) containing quantum dots (QDs) for cellular imaging. However, as an interesting issue of nano-bio interfaces, the mechanism of nanoparticle (NP) encapsulation by viral coat proteins remains unclear. Here, four kinds of QDs with the same core/shell but different surface coatings are tested for encapsulation. All the QDs can be encapsulated efficiently and there is no correlation between the encapsulation efficiency and the surface charge of the QDs. All the SV40 VNPs encapsulating differently modified QDs show similar structures, fluorescence properties, and activity in entering living cells. These results demonstrate the flexibility of SV40 major capsid protein VP1 in NP encapsulation and provide new clues to the mechanism of NP packaging by viral shells.