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 C=C double bonds of C-60. The GC-g-C-60 with 5 x 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 (similar to 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. (C) 2012 Elsevier B.V. All rights reserved.