Surface modification of liposomes

Abstract

Recent studies have demonstrated that drug delivery using liposomes provides several advantages, including increased stability, decreased systemic toxicity and increased maximum tolerated dosages. The aim of this study was to prepare polymer modified liposomes to enhance stability of liposome and prolonged drug release. In this study, two kinds of the monomeric liposomes containing 6-cholesteryl-1-hexyl methacrylate (Chol-C6 .M) and a mixture of Chol-C6 .M and poly(ethylene glycol) 400-dimethacrylate (PEG.DM) with lecithin phospholipids were prepared using a modified ethanol injection method. The monomeric liposomes were subsequently polymerized by using aqueous redox ammonium persulfate/sodium metabisulfite as initiators to improve the stability of liposomes. The prepared liposomes were characterized by FT-IR, 1H NMR, differential scanning calorimetry (DSC) and transition electron microscopy (TEM). The drug encapsulation efficiency was determined spectrophotometrically. In-vitro release studies were performed by using the dialysis method in phosphate buffered solution at 37 °C. DSC data showed the stability of the gel phase in PEG.DM/Chol-C<inf>6</inf>.M polymer modified liposomes. The TEM micrographs exhibited nano sized spherical shapes for all liposomes in which diameters were decreased from monomeric (240 nm) to polymerized liposomes (150 nm). The stability of liposomes was evaluated by turbidity measurement which indicated that both polymerized liposomes were more stable than the conventional and monomeric liposomes. It was concluded that the polymerized liposomes were more stable and capable to be used as a drug carrier for prolonged and sustained drug release. © ECV â€â Editio Cantor Verlag.