Polymer-associated liposomes as a novel delivery system for cyclodextrin-bound drugs

It is known that cyclodextrins (CDs) extract lipid components from bilayer of liposomes. This could undermine the potential benefits of liposomes as drug carriers. In this study, we demonstrated that PC-Chol liposomes with various CDs or rhapontin (Rh)–hydroxypropyl βCD (HP βCD) complexes could be stabilized by association with the amphiphilic polyelectrolyte, poly(methacrylic acid- co-stearyl methacrylate). Based on the results of differential scanning calorimetry, photocorrelation spectroscopy and transmission electron microscopy, the polymer-associated liposomes had the same vesicular form as liposome with clear boundaries and retained structural integrity for at least 1 month. In addition, the polymer-associated structure was unaffected by the type of CD, the composition and concentration of lipid components, and the concentration of the Rh-HP βCD complex. This contrasted with PC-Chol liposomes, whose structure was dependent on these factors. Using structurally different polymer-associated liposomes and PC-Chol liposomes containing the Rh-HP βCD complex, we also showed that the stability of vesicles could influence the skin permeability of CD-drug complexes. Association of amphiphilic polyelectrolytes to liposome helps stabilize the vesicle in the presence of cyclodextrin–drug conjugates.