Amphiphilic oligomer-based micelles as cisplatin nanocarriers for cancer therapy.

Polymeric micelles (∼10 nm) have been prepared from the amphiphilic oligomer comprising oligomeric polystyrene as the hydrophobic inner core and half of EDTA (-N(CH₂COOH)₂) as the hydrophilic outermost shell. After chelating cisplatin with -N(CH₂COOH)₂ in water, polymeric micelles containing Pt on the spherical surface have been easily obtained. Since the chelate group is introduced into the amphiphilic oligomer as the terminal group by a RAFT agent, the chelation of cisplatin with PS(COOH)₂ is almost stoichiometric. The drug carrier based on PS(COOH)₂ showed a high loading efficiency (>70%) towards cisplatin. The release of the therapeutic Pt from the cisplatin-loaded composites (PS(COOH)₂-Pt) triggered under weak acidic conditions resulted in good Pt-release and accumulation in tumor cells. Both in vitro and in vivo, the chelated cisplatin inhibited Sk-Br3 cancer more effectively than the intact cisplatin does. Furthermore, neither PS(COOH)₂ nor PS(COOH)₂-Pt showed obvious systematic toxicity.