Photodynamic therapy using glycol chitosan grafted fullerenes.

Glycol chitosan (GC)-grafted fullerene (GC-g-C(60)) conjugates were developed for use in photodynamic therapy of tumor cells. GC-g-C(60) was synthesized in anhydrous benzene/dimethylsulfoxide (DMSO) co-solvent via the chemical conjugation of free amine groups of GC to CC double bonds of C(60). The GC-g-C(60) with 5×10(-4) C(60) molecules per one repeating unit of GC was soluble in water. As C(60) molecules conjugated to GC increased to 0.16 molecules per one repeating unit of GC, GC-g-C(60) started to form supramolecular assemblies (∼30 nm) stabilized in phosphate buffer saline (PBS, 150 mM, pH 7.4). Upon 670 nm light illumination, photo-responsive properties of GC-g-C(60) allowed tremendous singlet oxygen generation in tumor cells for super phototoxicity. GC-g-C(60) also showed highly increased tumor accumulation ability for in vivo tumor of KB tumor-bearing nude mice. It is expected that our GC-g-C(60) conjugate may be a good candidate for in vivo photodynamic therapy in various malignant tumor cells.