The effects of dendrimer size and central metal ions on photosensitizing properties of dendrimer porphyrins

A series of dendrimer porphyrins (GnDPM; n=generation of dendrimer, n=1-3; M=coordination metal, M=freebase, Zn, Pt) were prepared and their photosensitizing properties were compared. All GnDPM exhibited sharp absorption in organic solvents. However, the Soret absorptions of GnDPM(CO2H) in 10mM phosphate buffer solution (pH=7.4) are broader than those of GnDPM in organic solvents, indicating inhomogeneous microenvironments of the focal porphyrin derivatives. All G3DPM(CO2H) successfully formed globular polyion complex micelles that were uniform in size. Under dark conditions, all GnDPM(CO2H) showed negligible cytotoxicity. However, all samples exhibited concentration-dependent photocytotoxicity under light irradiation. In vitro photocytotoxicity as well as singlet oxygen generation revealed that G3DPZn(CO2H) is the best dendritic PS of the three different dendrimer porphyrin species.