Formation of Water-Soluble Complexes from Fullerene with Biocompatible Block Copolymers Bearing Pendant Glucose and Phosphorylcholine

Double-hydrophilic diblock copolymers, PMPC₁₀₀-block-PGEMA_n (M₁₀₀G_n), were synthesized via reversible addition–fragmentation chain transfer radical polymerization using glycosyloxyethyl methacrylate and 2-(methacryloyloxy)­ethyl phosphorylcholine. The degree of polymerization (DP) of the poly­(2-(methacryloyloxy) ethylphosphorylcholine) (PMPC) block was 100, whereas the DPs (n) of the poly­(glycosyloxyethyl methacrylate) PGEMA block were 18, 48, and 90. Water-soluble complexes of C₇₀/M₁₀₀G_n and fullerene (C₇₀) were prepared by grinding M₁₀₀G_n and C₇₀ powders in a mortar and adding phosphate-buffered saline (PBS) solution. PMPC can form a water-soluble complex with hydrophobic C₇₀ using the same method. Therefore, the C₇₀/M₁₀₀G_n complexes have a core–shell micelle-like particle structure possessing a C₇₀/PMPC core and PGEMA shells. The maximum amounts of solubilization of C₇₀ in PBS solutions using 2 g/L each of M₁₀₀G₁₈, M₁₀₀G₄₈, and M₁₀₀G₉₀ were 0.518, 0.358, and 0.257 g/L, respectively. The hydrodynamic radius (R_h) of C₇₀/M₁₀₀G_n in PBS solutions was 55–75 nm. Spherical aggregates with a similar size to the R_h were observed by transmission electron microscopy. When the C₇₀/M₁₀₀G_n PBS solutions were irradiated with visible light, singlet oxygen was generated from C₇₀ in the core. It is expected that the C₇₀/M₁₀₀G_n complexes can be applied to photosensitizers for photodynamic therapy treatments.