Modifications in the nanoparticle-protein interactions for tuning the protein adsorption and controlling the stability of complexes

Abstract

We report the pathways to suppress or enhance the protein adsorption on nanoparticles and thereby control the stability of the nanoparticle-protein complexes with the help of selective additives. This has been achieved by tuning the electrostatic interaction between the nanoparticles and proteins, in the presence of surfactant and multivalent counterions. The preferential binding of the proteins with the surfactant and multivalent ions induced charge reversibility of nanoparticles can lead to adsorption of an otherwise non-adsorbing protein and vice versa. The findings are demonstrated for anionic silica nanoparticles and two globular proteins [lysozyme (cationic) and bovine serum albumin (BSA) (anionic)] as model systems, in the presence of two ionic surfactants [anionic sodium dodecyl sulfate (SDS) and cationic dodecyltrimethylammonium bromide (DTAB)], and ZrCl4 as multivalent salt. Small-angle neutron scattering with the unique advantage of contrast variation has been used to probe the role of individual components in the multi-component system. It is shown that the non-adsorbing behavior of BSA with silica nanoparticles changes into adsorbing in the presence of oppositely charged DTAB surfactant, whereas the strong adsorbing behavior of lysozyme on nanoparticles modifies to be non-adsorbing in the presence of oppositely charged SDS surfactant. The presence of multivalent counterions (ZrCl4) leads the charge reversal of the nanoparticles, transforming the lysozyme from adsorbing to non-adsorbing, and no significant change in the behavior of BSA. The results presented can find potential applications in the field of nanobiotechnology.