Figure 2.

Verifying the trajectory analysis algorithm using SME system (n = 16). (A) A representative prescribed trajectory is composed of Brownian diffusion (BD), confined diffusion (CD), directed diffusion (DD), and immobilization (IM). Simulated conditions are Brownian diffusivity D_pre = 0.08 μm²/s, linear dimension of the confinement L_pre = 100 nm, probability of penetration P = 0.01, and speed of directed diffusion V_pre = 2 μm/s. The track duration is 35 s, and the trajectory is equally divided into seven 5-s-long regions in which the tracked particle exhibits four types of motional modes in the following sequence: CD→BD→CD→DD→CD→BD→IM. The red arrowhead marks the starting point of the trajectory. The green arrows mark the regions exhibiting confined diffusion and the black arrow marks the immobilization region. (B) Time traces of the three classification parameters (α, Δϕ, Λ) and instantaneous velocity (V_i) of the representative trajectory shown in (A). (C) The ensemble-averaged MSD curves from the classified regions were fitted with the proper models to recover the dynamic parameters (D_Brn, L, and V). The R-squared values were employed to evaluate the goodness-of-fit. Ribbons represent the standard deviations. (D) Normalized histograms of experimentally derived dynamic parameters logV (red), logD_Brn (blue), and logL (green) are provided. The means and standard deviations were from curve fitting with a Gaussian mixture model. The total number of trajectories analyzed is 16 in (C) and (D). To see this figure in color, go online.