Mixtures of Thermotropic Mesogens as Components of Model DPPC Membranes: Effects of Intermolecular Interactions on Phase Transitions

Abstract

Thermotropic mesogens of different chemical nature - 4-pentyl-4′-cyanobiphenyl (5CB), azoxy nematic ZhK-440, and cholesteryl oleyl carbonate (COC) were introduced as dopants to hydrated DPPC, with their effects on phase transitions recorded by DSC. When mesogen pairs (5CB + ZhK-440 and 5CB + COC) were added at constant total concentration, dependence of transition temperature to L_α phase on 5CB concentration was linear for COC and nonlinear for ZhK-440, with effects of cyanobiphenyl-azoxybenzene charge transfer complexes manifested in both types of mesophases. Such dual doping of hydrated DPPC allows modeling of drug-membrane interactions in the case of joint application of different drugs.

Keywords:

• Differential scanning calorimetry
• intermolecular interaction
• liquid crystal mixtures
• lyotropic mesophases
• phase transitions
• phospholipid model membranes