A novel approach to synthesize polymers for potential photodynamic therapy: from benzenedinitrile to phthalocyanine

作者:Wang Laibing; Li Jun; Zhang Weidong; Chen Gaojian*; Zhang Wei; Zhu Xiulin
来源:Polymer Chemistry, 2014, 5(8): 2872-2879.
DOI:10.1039/c3py01129a

摘要

Benzenedinitrile, a precursor for the synthesis of phthalocyanine, was incorporated into a methacrylate monomer, 2-methyl-acrylic acid 6-(3,4-dicyano-phenoxy)-hexyl ester (MADCE). The benzenedinitrile monomer was homo-polymerized, chain-extended and copolymerized with oligo(ethylene glycol) methyl methacrylate (OEGMEMA) via the reversible addition-fragmentation chain transfer (RAFT) method. The resulting homopolymer, block and random copolymers obtained were used to synthesize polymers with Zn(II)phthalocyanine (ZnPc) side-chains by reacting with excess benzenedinitrile derivatives, 4-(octyloxy)phthalonitrile (OPN). GPC, FTIR, UV-Vis, NMR, fluorescence, and atomic absorption spectroscopy were used to characterize the Zn(II)phthalocyanine-functionalized polymers. The ZnPc-functionalized polymers generate singlet oxygen species with good quantum yields, which are believed to be the major cytotoxic reactive oxygen species (ROS) for photodynamic therapy. Among them, copolymers present enhanced singlet oxygen quantum yields (Phi(Delta) = 0.49 and 0.40 in DMF, Phi(Delta) = 0.68 and 0.73 in aqueous media) compared to the homopolymer (Phi(Delta) - 0.28). The ZnPc-functionalized copolymers self-assembled into nanoparticles in aqueous solutions, which was confirmed by DLS and TEM, and the nanoparticles show good stability in the presence of salt and proteins. This novel and efficient method of synthesizing water-soluble ZnPc-functionalized polymers with good singlet oxygen quantum yields provides a simple approach to fabricate polymeric materials for photodynamic therapy.