liposomebinding

Liposomebinding refers to the association of molecules with liposomes, which are spherical vesicles composed of phospholipid bilayers. Liposomes serve as model membranes in biophysical studies and as carriers for drug delivery, diagnostics, and research in membrane biology. Binding can occur on the outer surface or, for certain designs, within or across the bilayer without necessarily causing fusion.

Binding mechanisms include electrostatic attraction between charged lipid headgroups and oppositely charged regions of the binding molecule, hydrophobic or amphipathic insertion of helices or lipophilic moieties into the bilayer, and specific lipid–protein interactions that recognize headgroup motifs or lipid species. Some proteins possess lipid-binding domains such as C2 or PH domains that mediate selective affinity for particular lipids. Calcium-dependent binding is also common for certain peripheral membrane proteins.

Determinants of liposomebinding include liposome composition (lipid types, charge, cholesterol content), size and curvature, lipid phase (gel versus liquid-ordered), and the presence of specific lipid headgroups. Experimental conditions such as ionic strength, pH, temperature, and the concentration and affinity of the binding molecule also influence binding.

Measurement and analysis methods encompass co-sedimentation or flotation assays, surface plasmon resonance, isothermal titration calorimetry, fluorescence-based assays with labeled liposomes, and cryo-electron microscopy. A key distinction is that binding does not inherently involve lipid mixing or fusion; fusion requires additional steps and factors.

Applications span basic membrane biology, characterization of peripheral membrane proteins, liposome-based drug delivery, and assay development for studying protein–lipid interactions.