Dynamics of intracellular diffusion under various intracellular spatial dimensions

Diffusion is crucial for biomolecule transportation in cells and is the physical basis for various life processes． Due to complexity of intracellular microenvironment, biomolecule diffusion inside cells exhibits novel dynamic characteristics such as anomalous diffusion, spatial heterogeneity, and anisotropy． The relationship between intracellular diffusion dynamics and spatial dimensions of intracellular microenvironment is not well understood． Live-cell single-molecule fluorescence tracking techniques were used in this study to investigate the diffusion of quantum dots inside cells, to quantitatively analyze dynamic features of intracellular quasi-two-dimensional diffusion and quasi-one-dimensional diffusion in filopodia． Compared to intracellular quasi-two-dimensional diffusion, diffusion within filopodia was found to exhibit higher rate, and the phenomenon of diffusion acceleration was inversely proportional to the diameter of the filopodia, suggesting that the filopodia is a more efficient pathway for intracellular substance transport． The relationship between intracellular diffusion dynamics and spatial dimensions of intracellular environment is elucidated, mechanisms of cellular regulation of biomolecule transport through subcellular structures are clarified．