Channel-facilitated diffusion boosted by particle binding at the channel entrance
Physical Review Letters
American Physical Society
We investigate single-file diffusion of Brownian particles in arrays of closely confining microchannels permeated by a variety of attractive optical potentials and connecting two baths with equal particle concentration. We simultaneously test free diffusion in the channel, diffusion in optical traps coupled in the center of the channel, and diffusion in traps extending into the baths. We found that both classes of attractive optical potentials enhance the translocation rate through the channel with respect to free diffusion. Surprisingly, for the latter class of potentials we measure a 40-fold enhancement in the translocation rate with respect to free diffusion and find a sublinear power law dependence of the translocation rate on the average number of particles in the channel. Our results reveal the function of particle binding at the channel entrances for diffusive transport and open the way to a better understanding of membrane transport and design of synthetic membranes with enhanced diffusion rate.
S. P. acknowledges support from the Leverhulme and Newton Trust through an Early Career Fellowship. S. L. D. acknowledges funding from the German Academic Exchange Service (DAAD) and the German National Academic Foundation. U. F. K. was supported by an ERC starting grant.
This is the final version of the article. Available from the publisher via the DOI in this record.
Vol. 113, 048102
Place of publication