Association Behavior of the Synthetic Protein-lipid Complex Analogues

Hypercoiling poly(styrene-alt-maleic anhydride) (PSMA) is known to undergo conformational transition in response to environmental stimuli. This behavior allows it to associate with the phospholipid, 2-dilauryl-sn-glycero-3-phosphocholine (DLPC) to produce nanostructures analogous to lipoproteins. The complex represents a new bio-mimetic delivery vehicle with applications in the cosmetic and pharmaceutical industries. This study investigates, for the first time, the association behavior of PSMA and DLPC through the combination of different analytical techniques. The results indicate that the association is primarily driven by hydrophobic interactions and depends on various factors including the polymer/lipid ratio, the polymer molecular weight and the pH of the aqueous environment. The conformational transition of PSMA leads to the formation of discrete micellar complexes involving anisotropic-to-isotropic lipid phase transformation. As the number of hydrophobic moieties in the polymer is increased, the pH-dependent conformational transition of the polymer plays less important part in achieving this phase transition of the lipid.