DSC studies of the phase transition behavior of synthetic bilayer membranes. Part III. Bilayer membranes of phosphate amphiphiles

The gel-to-liquid crystal phase transition of bilayer membranes of synthetic phosphate amphiphiles was systematically examined by differential scanning calorimetry (DSC). The phosphate amphiphiles are mostly of the double- chain type, though a small number of single-chain and triple- chain amphiphiles are included. The agreement of the phase transition temperature (T_c) as determined by DSC and other methods was only approximate. The T_c values were raised with increasing lengths of the alkyl tail, and by incorporating the aromatic unit in the spacer portion. As for the head group, T_c was lowered with progressive neutralization, but Ca²⁺ binding raised T_c.