Controlled supramolecular self-assembly of "supercharged β-lactoglobulin A - PEG conjugates" into nanocapsules.

The synthesis and characterization of a new protein-polymer conjugate composed of lactoglobulinA (LGA) and poly(ethylene glycol) PEG is described. LGA was selectively modified to self-assemble by super-charging via amination or succinylation followed by conjugation with PEG. An equimolar mixture of the oppositely charged protein-polymer conjugates self-assemble into spherical capsules of 80-100nm in diameter. The self-assembly proceeds by taking simultaneous advantage of the amphiphilicity and polyelectrolyte nature of the protein-polymer conjugate. These protein-polymer capsules or proteinosomes are reminiscent of protein capsids, and are capable of encapsulating solutes in their interior. We envisage this approach to be applicable to other globular proteins.