Enzyme-Regulated Non-Thermal Fluctuations Enhance Ligand Diffusion and Receptor-Mediated Endocytosis

Active enzymes generate significant mechanical fluctuations while catalyzing chemical reactions, which can influence the dynamics of their surroundings. This phenomenon opens new avenues for controlling mass transport in complex and dynamically inhomogeneous environments through localized chemical reactions. Herein, we studied the uptake of transferrin molecules in retinal pigment epithelial cells via clathrin-mediated endocytosis. In the presence of enzyme catalysis in the extracellular environment, we observed a significant enhancement in the transport of fluorophore-tagged transferrin inside the cells. Total internal reflection fluorescence microscopy and fluorescence correlation spectroscopy measurements showed a substantial increase in transferrin diffusion in the presence of active fluctuations. This study sheds light on the possibility that enzyme-substrate reactions within the extracellular environment may induce long-range mechanical influences, facilitating targeted material delivery within the intracellular milieu more efficiently than passive diffusion. These insights could contribute to the development of better therapeutic strategies by overcoming limitations imposed by slow molecular diffusion under complex environments.