A Biophysical Research on the Determination of Morphological and Structural Properties of Coumarin-Loaded Liposomes

The major goal of this research was to examine how coumarin affects lipid model membranes. For this reason, liposome membranes were formed using dimyristoyl phosphatidylcholine (DMPC) as zwitterionic lipid. The influence of coumarin on the morphology, packing order, fluidity, and hydration state of lipid membranes was specifically investigated by means of microscopic (field emission scanning electron microscopy (FE-SEM)) and spectroscopic (attenuated total reflection Fourier transform infrared (ATR-FTIR) spectroscopy) techniques. Taken into account the results obtained with FE-SEM images and analysis, liposomes without and with coumarin have uniform structures and spherical shapes in appearance. However, coumarin-loaded liposomes are observed with an increase in size when compared to a mean diameter of unloaded-liposomes. Considering ATR-FTIR analysis, the investigation of the vibrational bands which belong to the hydrophobic and hydrophilic parts of DMPC lipid reveals that coumarin alters the physical features of the DMPC liposomes by decreasing the order and increasing the fluidity of the system and making hydrogen bonding with the interfacial and headgroup regions of zwitterionic lipid DMPC. Finally, performing more biophysical studies on the interactions of biologically active compounds with model membranes plays an important role in determining the molecular action mechanisms of these compounds in drug discovery and formulations.