Design, synthesis and evaluation of liposomes modified with dendritic aspartic acid for bone-specific targeting

Bone diseases are notoriously difficult diseases to treat due to the comparatively low blood flows in bone tissue. Therefore, targeting delivery of drugs to bone may not only enhance the treatment efficacy, but also reduce the quantity of drug administered. In order to increase the distribution of paclitaxel (PTX) in bone, in this study, a series of novel dendritic aspartic acid derivatives were designed and synthesized as liposome ligands to deliver PTX to bone effectively. The liposomes were prepared by thin film hydration method and its particle size, zeta potential, encapsulation efficiency, release profile, stability, hemolysis were also characterized. All the aspartic acid-coated liposomes showed more than 60% binding rates to hydroxyapatite (HAP), especially the PTX-Asp₈-Lip exhibited dramatic binding rates (> 97%) after 24 h. Moreover, the bone-targeting study in vivo indicated that all liposomes could improve the accumulation of PTX in bone, among which, the PTX-Asp₈-Lip showed the best affinity due to the increase of aspartic acid residues exposed on the liposome surface. These results provided a novel and effective entry to the development of bone-targeting drugs.