How the number of fitting points for the slope of the mean-square displacement influences the experimentally determined particle size distribution from single-particle tracking.

The size distribution of nanoparticles can be determined by single-particle tracking. This yields the mean-squared displacement (MSD) as a function of the lag time, and for normal diffusion the slope of this curve is directly related to the diffusion coefficient or via the Stokes-Einstein relation to the particle size. Here we demonstrate how the experimentally determined size distributions are affected by the number of fitting points used to determine the slope of the MSD curve.