(53j) Adsorption of Myoglobin on Silica Nanoparticles

The adsorption of proteins from aqueous medium onto the solid surface is governed by a complex interplay of surface interactions, such as electrostatics, van der Waals, hydrophobic, hydrogen bonding, and solvation. However, the contribution of each of these interaction potentials in the protein adsorption process is currently poorly understood due to non-uniform surface distribution of chemical functional groups and anisotropic shape of the protein molecules. Here, we investigate the effect of pH and dispersion salinity on the binding of a model protein, myoglobin, onto silica nanoparticles. We measure adsorption isotherms of the protein on nanoparticles and analyze based on Guggenheim-Anderson-de Boer model. The isotherms and their analysis show that the myoglobin molecules form patchy multilayer on the surface of silica nanoparticles. We show that the amount of protein adsorbed on silica nanoparticle is strongly dependent on the pH and dispersion salinity. We further correlate this change in protein adsorption with the local electrostatic interactions between myoglobin molecules and silica nanoparticles. This study uncovers the role of surface charge distribution of protein on its packing onto charged interfaces and thus lays a foundation to understand the mechanism of protein corona formation on NPs.