New amphiphilic silicon(IV) phthalocyanines as efficient Photosensitizers for photodynamic therapy: Synthesis, photophysical properties, and in vitro photodynamic activities

A novel series of silicon(IV) phthalocyanines substituted axially with one or two 1,3-bis(dimethylamino)-2-propoxy group(s) have been prepared by ligand substitution and alkoxy exchange reactions. Two dicationic and tetracationic phthalocyanines have also been prepared by methylation of two of these compounds. The nomomic phthalocyanines are essentially nonaggregated in common organic solvents and show a weak fluorescence emission, while the methylated derivatives phage cells with IC50 values down to 0.02 mum. The photodynamic activities are related to the cellular uptake and the efficiency to generate singlet oxygen. A higher positive charge at the phthalocyanine hinders the uptake, reflected by the lower intracellular fluorescence intensity. Fluorescence microscopic studies have also revealed that the unsymmetrical phthalocyanine SiPc[C3H5(NMe2)(2)O](OMe) (4) has a high and selective affinity to the mitochondria of HepG2 cells.