The nanocaterpillar's random walk: diffusion with ligand–receptor contacts

Abstract

Particles with ligand-receptor contacts bind and unbind fluctuating ``legs" to surfaces, whose fluctuations cause the particle to diffuse. Quantifying the diffusion of such ``nanoscale caterpillars" is a challenge, since binding...

Mass Changes the Diffusion Coefficient of Particles with Ligand-Receptor Contacts in the Overdamped Limit

“…1, inset). Using standard coarse-graining techniques [20,34,35], we derive an analytic expression, verified by simulations, that shows the long-time diffusion coefficient D eff (m) decreases with mass (Fig. 1, blue line).…”

“…Such particles are coated with sticky ligands that bind and unbind to receptors on an opposing surface, changing the particle's mobility [8,10,17,18]. The ligand binding and unbinding rates can be fast, in some cases comparable to 1/τ m [19,20]. One might speculate that when binding occurs on the same timescale as the relaxation of the ambient fluid's momentum, the coupling between binding dynamics and momentum relaxation could lead to inertial effects at longer timescales [2,[4][5][6][21][22][23][24][25][26][27].…”

“…Furthermore, we have recently pointed out that models of DNA-coated colloids find different long-time diffusion coefficients when they start with the underdamped Langevin equation for particle motion [30] (Fig. 1, dotted line) or from the overdamped equation [20] (Fig. 1, dashed line).…”

“…( 5) Simulation from the overdamped Langevin equation, Ref. [20] from the underdamped Langevin equation, Ref. [30] FIG.…”

“…Our model starts with the approach we introduced for overdamped dynamics in Ref. [20] as we have shown it reproduces the experimentally observed diffusion of certain DNA-coated colloids, yet we modify the model to include a dependence on mass. The particle's motion is investigated in 1D, on the lateral dimension parallel to the surface.…”