Formation of Poly-L-Lysine-Porphyrin Derivative Complex Exhibiting Diminished Dark Toxicity in Aqueous Solutions and High Photodynamic Activity.

Poly-L-lysine (PLL) displays a high solubilizing ability for hydrophobic guest molecules, and when in complexes with guest molecules, it exhibits a high intracellular uptake. However, its high cytotoxicity, originating from its cationic character, significantly limits its applications in biological and medicinal chemistry. In this study, the amount of free PLL in an aqueous solution of a PLL-porphyrin complex was immensely reduced, resulting in considerably lower dark toxicity than that of the free PLL. Furthermore, the PLL-porphyrin complex exhibited high photodynamic activity under photoirradiation at 610-740 nm.