Thermodynamics of Protein Adsorption on Gold and Silica Nanoparticles

Abstract

Nanoparticle-based biomedical applications in disease diagnostics, site targeting, drug delivery, etc., have been pursued vigorously with the hope of finding better solutions than conventional diagnostics and therapeutics. During any such application the nano surface will get exposed to complex biological fluids which may lead to the adsorption of layers of proteins (or other biomolecules), popularly known as “Nanoparticle-protein corona (NPC)”. Proteins having high affinity and longer residence time on the surface form hard corona (first layer) while soft corona (subsequent layers) is formed by proteins that interact weakly with the first adsorbed layer on the surface. Although a few nanoformulations have been approved for human trial, enormous challenges persist for their safe and successful implementation, mainly due to poor understanding of the energetics associated with the stability of NPC formation. The mechanism of protein adsorption on nanoparticles is thus essential for their safe use in nanomedicine and novel nano formulations. In my thesis work, I have employed mainly second harmonic light scattering (SHLS) and dynamic light scattering (DLS) techniques in solution to probe the thermodynamics of adsorption of proteins on biocompatible gold and silica nanoparticles. The important thermodynamic parameters like binding constant, binding stoichiometry, Gibbs free energy (G), enthalpy (H), and entropy (S) of NPC formation were all extracted after fitting the scattering data with various adsorption models