Use of a polycation spacer for noncovalent immobilization of albumin on thermally modified virus particles

The noncovalent immobilization of the protein bovine serum albumin on the surface of spherical nanoparticles 330 ± 60 nm in diameter is described. These nanoparticles are prepared by the thermal treatment of tobacco mosaic virus and are preliminarily covered with a layer of the cationic polymer poly(N-ethyl-4-vinylpyridinium bromide). The electrostatic adsorption of the polycation on the surface of negatively charged spherical nanoparticles (on average 1.2 × 10⁴ macromolecules per particle) is accompanied by recharging of the surface; as a result, the negatively charged protein bovine serum albumin can be adsorbed on it in an amount of 1.7 × 10⁴ molecules per particle. The modification of spherical nanoparticles with the polycation and protein does not cause the aggregation of particles. The spherical-nanoparticle-polycation-protein ternary complex demonstrates increased stability in salt solutions relative to the spherical-nanoparticle-polycation binary complex. Because of the simplicity of the method used to modify the surface of spherical nanoparticles, it shows promise for preparation of functionally active complexes.