Biothermal Analysis of Interactions between Delocalized Lipophilic Cation (DLC) and Composite Lipid Bilayer

Delocalized lipophilic cations exhibit a heightened biological effect as a result of interaction and passing through the phospholipid bilayer or the cell membrane. The interaction between delocalized lipophilic cations (DLC) and lipid bilayer results in changes in the physicochemical properties of the bilayer. In this work, the mechanism of interaction of a cyanine based DLC and a composite bilayer composed of charged lipids has been investigated. The nature of binding and internalization has been ascertained through thermo-analytic techniques such as nano DSC and nano ITC. The values of dissociation constant (Kd), Gibbs Free Energy (ΔG), partition coefficient (Pm), and no. of binding sites (n) from these techniques have been compared to determine if the binding affinity is enthalpy or entropy driven. It has been concluded that the lipophilicity of the cyanine molecule governs the number of the binding sites (n) required on the bilayer, which in-turn affects the enthalpy of the binding.