pH-Dependent complexation of poly(acrylic acid) derivatives with phospholipid vesicle membranes

Poly(acrylic acid), poly(methacrylic acid), and poly(α-ethylacrylic acid) can be used to modify, in a pH-dependent manner, the properties of phospholipid vesicle membranes. Polymer-lipid complexation caw a decrease in the apparent cooperativity of the lipid melting transition. The "critical pH" for complexation may be controlled through variation of the chemical structure and the tacticity of the poly(carboxylic acid), It is suggested that an important driving force for complexation is provided by the formation of hydrogen bonds between un-ionized carboxyl groups of the polymer and the phosphodiester functions of the lipid surface