Iodinated photosensitizing chitosan: self-assembly into tumor-homing nanoparticles with enhanced singlet oxygen generation.

A novel iodinated chitosan-backboned conjugate (GC-I-Ce6) was designed and prepared to fabricate self-assembled biopolymeric nanoparticles with heavy atom-effected enhanced singlet oxygen generation as well as biological merits. The heavy atom-rich nature of the hydrophobic particle interior was characterized with X-ray absorption and the modified photophysical properties of a chemically embedded photosensitizer, chlorin e6 (Ce6). From the comparative spectroscopic studies as well as cellular and animal experiments, it has been shown that the self-assembled GC-I-Ce6 nanoparticles have enhanced capability of singlet oxygen generation by the intraparticle heavy-atom effect, along with high tumor targetability in vitro and in vivo thanks to the glycol chitosan-surfaced exterior with biocompatible, positively charged and tumor-homing characteristics. Actual efficacy improvement in the photodynamic therapy of a human breast cancer cell line (MDA-MB-231) demonstrates potential of our photophysically and pharmaceutically motivated hybrid bioconjugate approach for nanomedicine applications.