A SIMULATION STUDY OF FLEXIBLE ZWITTERIONIC MONOLAYERS - EFFECTS OF SOLVENCY AND SPACER MOLECULES

We consider the numerical simulation of two opposing layers of zwitterion molecules. We address two contributions of the solvent: (1) changes in the dielectric screening of the electrostatic interaction between the zwitterions and (2) the long-range interaction of hydrated molecules. Further, we study a system of mixed monolayers, zwitterions/neutral spacer molecules. This work stems from experimental conditions which are argued to limit the validity of the entropic fluctuation contribution considered responsible for the repulsion between phospholipid bilayers. We find that these factors do not place the above mechanism in doubt. We explain one specific experimental finding, and we place our model into context with the appropriate experimental situation.