Adsorption of intact DPPG liposome on rough polyelectrolyte multilayers

In this work, it is demonstrated that dipalmitoyl phosphatidyl glycerol (DPPG) liposomes can be adsorbed without rupture on a rough polyelectrolyte layer-by-layer (LbL) film. The adsorption kinetic curves revealed that this process is governed by a diffusion phenomenon with a characteristic time of approximately 20 minutes. These were obtained by placing the solid support with polyelectrolyte multilayers (PEM) in water and injecting a concentrated DPPG liposome solution. The total adsorbed amount per unit of area obtained by quartz crystal microbalance (QCM) revealed that the integrity of the liposomes was maintained during adsorption. The analysis of the surface topographies acquired by atomic force microscopy (AFM) of PEM and PEM with DPPG liposome adsorbed, revealed that the intact DPPG liposome are randomly adsorbed on the PEM surface, filling the PEM valleys and increasing the roughness. The height distribution functions were calculated and demonstrated that the height of the adsorbed liposomes ranges nearly 30-40 nm which agrees with the values of liposome diameter size in solution achieved by dynamic light scattering (DLS).