Behavior of self-organized molecular assemblies composed of phosphatidylcholines and synthetic triple-chain amphiphiles in water

The enhancing effect of synthetic triple-chain amphiphiles on the stability of a vesicle made from phosphatidylcholine was investigated in terms of th e leakage of the inner marker. The addition of amphiphiles bearing three hy drophobic chains and two carboxylate groups to the vesicle membrane with a phosphatidylcholine base contributed effectively to strengthening the barri er effect of the membrane of the vesicle. The leakage of entrapped material s was suppressed with increasing ratio of the triple-chain amphiphile in th e membrane. To elucidate the factors which bring about the high barrier eff ect of the triple-chain amphiphile, the zeta potential of the vesicle, micr ofluidity of the bilayer membrane, pressure-area (pi-A) isotherms of the mo nolayer membrane, and differential scanning calorimetry of the amphiphiles were studied. Both the increasing surface charge of the vesicle and the enh ancement of the hydrophobic interaction near the hydrophile moiety of the b ilayer membrane were considered to contribute to the stability of the vesic le containing the triple-chain amphiphile. It was also found that the micro fluidity of the bilayer membrane made from triple-chain amphiphiles was les s sensitive to temperature change than that of the bilayer membrane made fr om phosphatidylcholine.