摘要
Molecular motion provides a way for biomolecules to mix and interact in living systems.Quantifying their motion is critical to the understanding of how biomolecules perform its function.However,it has been a challenged task to spatially map the fast diffusion of unbound proteins in the heterogenous intracellular environment.Here we reported a new imaging technique named cumulative area based on single-molecule diffusivity mapping(CA-SMdM).The strategy is based on the comparison of singlemolecule images between a shorter and longer exposure time.With longer exposure time,molecules will travel further,thus giving more blurred single-molecule images,hence implying its local diffusion rates.We validated our technique through measuring the fast diffusion rates(10–40μm~2/s)of fluorescent dye in glycerol-water mixture,and found the values fit well with Stokes-Einstein equation.We further showed that the spatially mapping of diffusivity in live cells is plausible through CA-SMdM,and it faithfully reported the local diffusivity heterogeneity in cytosol and nucleus.CA-SMdM provides an efficient way to mapping the local molecular motion,and therefore will have profound applications in probing the biomolecular interactions for living systems.
基金
supported by the National Key R&D Program of China(2022YFA1305400)
the National Natural Science Foundation of China(22104113,22274122)。
