Biopolymers, biological membranes, and other cellular components

are electrically charged. Electrostatic interactions in biological sys-

tems are therefore of fundamental importance in understanding the

interactions between charged molecules and membrane surfaces.

Examples of electrically charged systems from biology include

self-assembling dispersions such as spherical (inverse) micelles

(Fig. 6.1), phospholipid vesicles (Fig. 6.6), and microemulsions

(Israelachvili, 1997; Safran, 1994). Such objects are formed by

aggregation of amphiphilic molecules in such a way that the

hydrophilic parts of the molecules are in contact with electrolyte

solutions. Microemulsions are formed in mixtures of amphiphiles,

water, and oil, where domains of water (in oil) or oil (in water) are

separated by surfactant monolayers.