Surface Plasmon Resonance Imaging Microscopy of Liposomes and Liposome-Encapsulated Gold Nanoparticles

Liposomes are small vesicles that can be used in various targeting applications as carrier vehicles. In this paper, we show that realtime surface plasmon resonance imaging microscopy (SPRI microscopy) can be used to detect diffraction patterns of these singular vesicles in water phase at room temperature and without any additives. The diffraction pattern intensities, related to the particle size, are shown to follow the lognormal distribution in a cumulative distribution function (CDF) that is very well in accordance with the normal size distribution of liposomes prepared with the extrusion method. In addition, this distribution is further analyzed to determine the number of gold nanoparticle (GNP) encapsulated liposomes in a set of liposomal adsorption events. Thus, we obtain the encapsulation efficiency and present a method to study the intrinsic properties of liposomes and other soft nanomaterials.