Noncircular pores in model membranes: A calculation of the effect of pore geometry on the partition of a solute

The partition of a solute between a bulk phase and the rhomboidal pores of tracketched membranes is studied theoretically. The partition coefficient is concentration dependent and is reported (to first order in the bulk phase concentration) for varying solute sizes. A generalization to the case of pores of general polygonal cross section shows that narrow pore corners greatly enhance the partition coefficient due to the accumulation of solute in them. The use of an equivalent circular pore underestimates the equilibrium partition coefficient because it neglects the presence of corners.