Effects of multiple occupancy and inter-particle interactions on selective transport through narrow channels: theory versus experiment

TL;DR

This paper develops a kinetic theory to analyze how multiple occupancy and inter-particle interactions influence selective transport in narrow channels, aligning theoretical predictions with experimental data and guiding artificial sieve design.

Contribution

It introduces a general kinetic model that accounts for multi-particle occupancy and interactions, providing insights into transport efficiency and selectivity mechanisms.

Findings

Inter-particle interactions significantly affect transport efficiency.

Model predictions align semi-quantitatively with experimental data.

Conditions for achieving selective transport are identified.

Abstract

Many biological and artificial transport channels function without direct input of metabolic energy during a transport event and without structural rearrangements involving transitions from a 'closed' to an 'open' state. Nevertheless, such channels are able to maintain efficient and selective transport. It has been proposed that attractive interactions between the transported molecules and the channel can increase the transport efficiency and that the selectivity of such channels can be based on the strength of the interaction of the specifically transported molecules with the channel. Herein, we study the transport through narrow channels in a framework of a general kinetic theory, which naturally incorporates multi-particle occupancy of the channel and non-single-file transport. We study how the transport efficiency and the probability of translocation through the channel are affected by inter-particle interactions in the confined space inside the channel, and establish conditions for selective transport. We compare the predictions of the model with the available experimental data - and find good semi-quantitative agreement. Finally, we discuss applications of the theory to the design of artificial nano-molecular sieves.