Brush-shaped RAFT polymer micelles as nanocarriers for a ruthenium (II) complex photodynamic anticancer drug

Amphiphilic polymers containing brush-shaped poly(polyethylene glycol methyl ether acrylate) (PEGA) as a hydrophilic segment may form a stable hydrophilic shell for a polymeric micelle due to a strong interaction among the brush shaped molecules. In this paper, polymeric micelles with brush-shaped poly(PEGA) as hydrophilic shell were designed and formulated as nanocarriers for a new ruthenium (II) complex anticancer drug to address its poor water solubility. Well defined brush-shaped poly(PEGA)-containing amphiphilic block polymers were synthesised by reversible addition-fragmentation chain transfer (RAFT) polymerisation. The as-prepared amphiphilic polymers formed stable polymeric micelle nanocarriers for the hydrophobic ruthenium (II) complex, resulting in greatly increased solubility of the drug by inhibiting its aggregation in aqueous environment. Cytotoxicity studies demonstrated that the use of polymeric micelle nanocarriers increased the drug's toxicity to human liver cancer cells (SK-HEP-1) by 3 fold under dark and 12 fold under light conditions. However, both bare drug and encapsulated drug showed no toxicity to the normal cells, demonstrating the drug's potential targeting capacity to cancer cells.