  Describing the diffusion of particles through crowded, confined environments
with which they can interact is of considerable biological and technological
interest. Under conditions where the confinement dimensions become comparable
to the particle dimensions, steric interactions between particles, as well as
particle-wall interactions, will play a crucial role in determining transport
properties. To elucidate the effects of these interactions on particle
transport, we consider the diffusion and binding of finite-size particles
within a channel whose diameter is comparable to the size of the particles.
Using a simple lattice model of this process, we calculate the steady-state
current and density profiles of both bound and free particles in the channel.
We show that the system can exhibit qualitatively different behavior depending
on the ratio of the channel width to the particle size. We also perform
simulations of this system, and find excellent agreement with our analytic
results.
