Abstract
The interaction of photoinitiators (benzil: BZ, camphoroquinone: CQ and 9-fluorenone: 9F plus 2-(dimethylamino) ethyl methacrylate: DM) with dimyristoyl phosphatidylcholine (DMPC) and dipalmitoyl phosphatidylcholine (DPPC) liposomes was investigated by the application of differential scanning calorimetry (DSC), to clarify their hemolytic activity1). The DSC data showed that the photoinitiators, when irradiated, caused large changes in the phase transition properties of the liposomes which were characterized by a shift of the phase transition temperature (T) to a lower temperature, a decrease in the enthalpy (ΔH), and a decrease in the height/half-height width (H/HHW) of cooperativity in an endothermic peak.
Paticularly, interactions of aromatic ketones (BZ/DM and 9F/DM) with the liposomes was markedly higher than that of aliphatic ketones (CQ/DM) during irradiation. The surface active complexes between photosensitizer (BZ, CQ and 9F) and the reducing agent (DM), which are formed during irradiation promoted a T shift and decrease in the ΔH and H/HHW value. Therefore, the surface active complexes probably cause the hemolysis during irradiation.
