Molecular approach to evaluate the integrity of the serum albumin adsorption layer on the surface of mixed iron oxide nanoparticles

A new approach to evaluate the stability and integrity of a protein layer coating the surface of magnetic iron oxide nanoparticles (IONPs) in an aqueous medium was described using human serum albumin (HSA) as an example. The approach envisages investigation of the catalytic (peroxidase-like) activity of IONPs characterized by the generation rate of a colored product of o-phenylenediamine oxidation and examination of the capability of IONPs of binding to the plasma protein immunoglobulin G (IgG) to form submicron- and micron-sized aggregates. A correlation between the generation rate of hydroxyl radicals and the integrity of the HSA coating on the IONP surface (confirmed by experiments using IgG) was established for the first time. The approach developed belongs to the methods with a gentle impact on systems (non-damaging and low-damaging methods) for in situ and ex situ applications. The approach provides new possibilities for studying the physicochemical properties of hybrid nanosystems or submicron systems at various steps of their synthesis, as well as near physiological conditions, for example, in the blood plasma.