Doxorubicin–PAMAM dendrimer complex attached to liposomes: Cytotoxic studies against human cancer cell lines

Liposomes composed of HePC:EPC:SA 10:10:0.1 (molar ratio) (1) and EPC:SA 10:0.1 (molar ratio) (2) were prepared and were used for incorporating the doxorubicin–PAMAM complex (3:1 molar ratio) (3). The doxorubicin–PAMAM complex was attached to liposomes and the incorporation efficiency was 91 and 95% for 1 and 2, respectively. The incorporation efficiency for doxorubicin into PAMAM was almost 97% while doxorubicin to PAMAM molar ratio was 3.56 ± 0.04. The release rate of doxorubicin as doxorubicin–PAMAM complex from liposomes 1 and 2 and from the complex 3, was studied using buffers and 50% RPMI cell culture medium at 37 and 25 °C. The low release rate of doxorubicin as well as the high incorporation efficiency of doxorubicin–PAMAM complex into liposomes are considered as beneficial factors concerning the activity of doxorubicin. The cytotoxic activity of the liposomal formulation 1 incorporating doxorubicin–PAMAM complex, based on doxorubicin activity, was compared to that of 2 incorporating doxorubicin–PAMAM complex and to that of 3. The results showed that complex 1 was the most active formulation against all cancer cell lines compared to that of 2 and 3. Liposomal formulations composed of lipids and of a drug–dendrimer complex could be characterized as modulatory liposomal controlled release system (MLCRS), and could provide benefits to the delivery of drugs and modulate their release.