Label-free analysis of adsorbed protein heterogeneity on individual particles, based on single particle collision events

Investigation of the heterogeneity of protein adsorption on particle surfaces has attracted enormous research attention owing to its great importance in fundamental studies and quality control. Herein we, for the first time, report a new method for label-free analysis of the heterogeneity of protein adsorption on single nanoparticles, based on particle collision events at the orifice of a nanopipette. The dwell time was strongly dependent on the amount of protein adsorbed on polystyrene particles, which could be used to analyze the heterogeneity of protein adsorption at the single particle level. This method presents a label-free, sensitive, reproducible and easily-operated way to analyze adsorption behavior at the single particle level, which opens a new approach to the study of the heterogeneity of physicochemical parameters at the surface of nanoparticles.