Improved Stability and Photodynamic Activity of Water-Soluble 5,15-Diazaporphyrins Incorporated in β-(1,3-1,6)-d-Glucan with On-Off Switch.

5,15-Diazaporphyrins, which have a large absorption at wavelengths over 600 nm, were dissolved in water by complex formation with β-(1,3-1,6)-d-glucans. Aqueous solutions of these complexes were relatively stable compared with their trimethyl-β-cyclodextrin-complexed analogues. β-Glucan-complexed diazaporphyrins showed quenched fluorescence and had low singlet-oxygen-generation abilities owing to random self-aggregation. However, external stimuli, such as the presence of liposomes or intracellular uptake, restored the fluorescence and singlet-oxygen-generation abilities of β-glucan-complexed diazaporphyrins. Consequently, β-glucan-complexed diazaporphyrins showed very high photodynamic activities toward HeLa cells.