Studying the Effect of Receptors Clustering on Hyaluronic Acid Binding with CD44 and the Cell Entry of Hyaluronic Acid Targeting Nanodrugs at Single Molecule/Particle Level

Receptor-ligand interactions on cell membrane play key roles in many physiological and pathological processes, especially in the nanodrug targeted delivery system. Hyaluronic acid (HA) is the main ligand for binding CD44 to modulate the targeted delivery of nanodrugs; however, the corresponding receptor clustering mechanism remains unclear. The differential effects of HA on CD44 clustering are closely associated with the number of disaccharide units. Herein, the binding dynamic parameters between CD44 and HA containing various disaccharide units were analyzed at the single-molecule level. Then, the clustering effect induced by HA containing various disaccharide units was evaluated and the optimal clustering effect was verified. Furthermore, the clustering effect on cell entry dynamic parameters of HA targeting nanodrugs was assessed based on different cell lines at the single particle level. These results demonstrate that the clustering effect will enhance the entry cell efficiency of HA targeting nanodrugs, and the effect is more obvious on the cell line with low expression level of CD44. This study offers a new way to evaluate the cell membrane receptor clustering and the corresponding effect on cellular uptake, which will provide potential strategy for designing appropriate targeting nanodrugs with high delivery efficiency tailored to different cancers.