Credit: © 2012 NPG

Nature Chem.http://doi.org/jbd (2012)

The combination of controlled polymer synthesis and proteins opens up the possibility of creating composite materials with well-defined structure and function, and inherent bioactivity. One route to such materials is the use of virus-like particle (VLP) proteins as scaffolds from which to grow or encapsulate polymeric material. Trevor Douglas and colleagues have now shown that by tailoring the location of initiator sites to the inside surface of VLP proteins based on the bacteriophage P22, polymerization restricted to the particles' interiors can be achieved. Thiol functions on the inside surface of the protein shells are selectively converted to initiator sites for atom-transfer radical polymerization, and on addition of suitable monomers, crosslinked poly(2-aminoethyl methacrylate) is encapsulated within (as pictured). The polymer has a high density of reactive amine groups that are available for the attachment of small functional molecules. For example, fluorescent dye molecules or gadolinium-based contrast agents for magnetic resonance imaging can be incorporated into the hybrid nanoparticles in much higher loadings than for previous VLP-based delivery systems.