Photosensitizer-encapsulated amphiphilic chitosan derivative micelles: Photoactivity and enhancement of phototoxicity against human pancreatic cancer cells

Photosensitizer-encapsulated amphiphilic chitosan derivative (Photosan-DA-Chit) micelles with controlled photoactivity have been prepared using a simple self-assembly method in phosphate-buffered saline (pH 6.2). The fluorescence quantum yield and fluorescence lifetime of the Photosan-DA-Chit micelles were lower than those of free Photosan, which indicated that the micelles were suppressing the photoactivity of Photosan. However, upon incubation with human pancreatic cancer cells (i.e., Panc-1 cells), the Photosan-DA-Chit micelles showed higher fluorescence activity than free Photosan and generated higher levels of reactive oxygen species under laser illumination. The Photosan-DA-Chit micelles therefore exhibited strong phototoxicity, which led to significant levels of apoptosis in the Panc-1 cells. In the absence of light, however, the Photosan-DA-Chit micelles showed no cytotoxicity. These results indicated that they could be used as a potential photodynamic therapy in pancreatic cancer. (C) 2014 Elsevier B.V. All rights reserved.