Channel-facilitated molecular transport: The role of strength and spatial distribution of interactions

- Molecular flux strongly depends on the strength of the molecule-pore interactions.
- There exists an optimal molecule-pore interaction potential for maximal flux.
- Volume of interactions depends inversely on the strength for maximal flux.
- Stronger interactions need more number of attractive sites for maximal flux.
- Channels with few special sites need more attractive sites for higher flux.

Molecular transport across channels and pores is critically important for multiple natural and industrial processes. Recent advances in single-molecule techniques have allowed researchers to probe translocation through nanopores with unprecedented spatial and temporal resolution. However, our understanding of the mechanisms of channel-facilitated molecular transport is still not complete. We present a theoretical approach that investigates the role of molecular interactions in the transport through channels. It is based on the discrete-state stochastic analysis that provides a fully analytical description of this complex process. It is found that a spatial distribution of the interactions strongly influences the translocation dynamics. We predict that there is the optimal distribution that leads to the maximal flux through the channel. It is also argued that the channel transport depends on the strength of the molecule-pore interactions, on the shape of interaction potentials and on the relative contributions of entrance and diffusion processes in the system. These observations are discussed using simple physical-chemical arguments.

93