Immobilization of ibuprofen-containing nanospheres in layer-by-layer films

Liposomes have been applied to many fields as nanocarriers, especially in drug delivery as active molecules may be entrapped either in their aqueous interior or onto the hydrophobic surface. In this paper we describe the fabrication of layer-by-layer (LbL) films made with liposomes incorporating the anti-inflammatory ibuprofen. The liposomes were made with dipalmitoyl phosphatidyl choline (DPPC), dipalmitoyl phosphatidyl glycerol (DPPG) and palmitoyl oleoyl phosphatidyl glycerol (POPG). LbL films were assembled via alternate adsorption of the polyamidoamine dendrimer (PAMAM), generation 4, and liposomes containing ibuprofen. According to dynamic light scattering measurements, the incorporation of ibuprofen caused DPPC and DPPG liposomes to become more stable, with a decrease in diameter from 140 to 74 nm and 132 to 63 nm, respectively. In contrast, liposomes from POPG became less stable, with an increase in size from 110 to 160 nm after ibuprofen incorporation. These results were confirmed by atomic force microscopy images of LbL films, which showed a large tendency to rupture for POPG liposomes. Film growth was monitored using nanogravimetry and UV-Vis spectroscopy, indicating that growth stops after 10 bilayers. The release of ibuprofen obtained with fluorescence measurements was slower for the liposomes, with decay times of 9.2 and 8.5 h for DPPG and POPG liposomes, respectively, than for the free drug with a decay time of 5.2 h. Ibuprofen could also be released from the LbL films made with DPPG and POPG liposomes, which is promising for further uses in patches.