A complex of cyclohexane-1,2-diaminoplatinum with an amphiphilic biodegradable polymer with pendant carboxyl groups

A biodegradable and amphiphilic copolymer, MPEG-b-P(LA-co-MCC), which contains pendant carboxyl groups, was chosen as a drug carrier for the active anticancer part (DACH-Pt) of oxaliplatin to form an MPEG-b-P(LA-co-MCC/Pt) complex. It was able to self-assemble into micelles with a mean diameter of 30-40 nm, and a surface potential near -10 mV. The typical platinum content was 10 wt.%. The micelles showed acid-responsive drug release kinetics, which is beneficial for drug release in the intracellular environment. The Pt(II) species were released mainly in the form of DACH-Pt-Cl(2) in 150 mM NaCl solution and DACH-Pt(2+)-(H(2)O)(2) in pure water according to the results obtained by high-performance liquid chromatography coupled with inductively coupled plasma mass spectrometry and X-ray photoelectron spectroscopy. In vitro evaluation showed that the micelles displayed the same or higher cytotoxicities against SKOV-3, HeLa, and EC-109 cancer cells compared with oxaliplatin. The enhanced cytotoxicity against SKOV-3 cells is attributed to effective internalization of the micelles by the cells via endocytosis and the sensitivity of SKOV-3 cells to platinum drugs. This novel biodegradable and amphiphilic copolymer-based platinum drug will have great potential application in clinical use.