Lymphatic targeting of zidovudine using surface-engineered liposomes.

The present investigation was aimed at lymphatic targeting of zidovudine (ZDV)-loaded surface-engineered liposomes (SE liposomes). Surface of liposomes was engineered by incorporation of charges (positive or negative) and site-specific ligand (mannose) in order to enhance localization to lymphatics, specifically to lymph node and spleen. Positively and negatively charged nanosized SE liposomes (120 +/- 10 nm) were prepared using stearylamine (SA) and dicetyl phosphate (DCP), respectively, while ligand-coated SE liposomes were prepared using mannose-terminated SA (mannose conjugate). The SE liposomes were characterized for shape and surface morphology, size, entrapment efficiency, and in vitro drug release. All the SE liposomes formulations showed biphasic ZDV release, whereas mannose-coated liposomes (MAN-Lip) significantly reduced (p < 0.05) drug release compared with conventional liposome (Lip). The organ distribution pattern of the SE liposomes exhibited significant reduction in free ZDV concentration in serum, whereas significantly increased quantity was detected in the spleen and lymph nodes (p < 0.05). Fluorescent microscopy suggested enhanced uptake and localization of the SE liposomes in the lymph nodes and spleen, which were in the order: mannose coated > negatively charged > positively charged > Lip. Thus, the SE liposomes appeared to be promising novel vesicular system for enhanced targeting of ZDV to lymphatics, in AIDS chemotherapy.