Shear-induced rotation enhances protein adsorption

Theories predicted that shear promotes desorption, but due to the presence of factors such as aggregation effects, it is difficult to observe how shear influences the adsorption and desorption of individual protein molecules. In this study, we employed high-throughput single-molecule tracking and molecular dynamics simulations to investigate how shear flow affects the adsorption kinetics of plasma proteins (including human serum albumin, immunoglobulin G, and fibrinogen) at solid-liquid interfaces. Over the studied shear rate range of 0 - 10³ s^-1, shear stress did not trigger the protein desorption. Notably, we observed a significant increase, up to two orders of magnitude, in the adsorption rate constants k_a, in the dilute limit at solid-liquid interfaces. However, this shear-induced increase in k_a diminished with increasing the protein concentrations. At least in the scenarios studied, these trends were consistent across all three types of proteins and two types of surfaces investigated. Through a systematic analysis combining control experiments, coarse-grained, and all-atom molecular dynamics simulations, we identified that the shear-induced increase in k_a could be attributed to enhanced protein rotational diffusion, thereby increasing the likelihood of favorable surface proximity for adsorption.