Synthesizing and evaluating the photodynamic efficacy of asymmetric heteroleptic A7B type novel lanthanide bis-phthalocyanine complexes

Abstract

In this study heteroleptic A7B type novel Lu(iii) and Eu(iii) lanthanide phthalocyanines (LnPc(Pox)[Pc′(AB3SH)]) with high extinction coefficients have been synthesized as candidate photosensitizers with reaction yields higher than 33%. The singlet oxygen quantum yields ofLuPc(Pox)[Pc′(AB3SH)]andEuPc(Pox)[Pc′(AB3SH)], respectively, were measured 17% and 1.4% by the direct method in THF. The singlet oxygen quantum yield ofLuPc(Pox)[Pc′(AB3SH)]in THF is the highest among lutetium(iii) bis-phthalocyanine complexes to date. The photodynamic efficacy of the heteroleptic lanthanide phthalocyanines was evaluated by measuring cell viabilities of A549 and BEAS-2B lung cells, selected to representingin vitromodels for testing cancer and normal cells against potential drugs. The cell viabilities demonstrated concentration dependent behavior and were varied by the type of phthalocyanines complexes. Irradiation of the cells for 30 minutes with LED array at 660 nm producing flux of 0.036 J cm−2s−1increased cell death forLuPcPox-OAc,LuPc(Pox)[Pc′(AB3SH)]andZnPc. The IC50concentrations ofLuPc(Pox)[Pc′(AB3SH)]andZnPcwere determined to be below 10 nM for both cell lines, agreeing very well with the singlet oxygen quantum yield measurements. These findings suggest thatLuPc(Pox)[Pc′(AB3SH)]and particularlyLuPcPox-OAcare promising drug candidates enabling lowered dose and shorter irradiation time for photodynamic therapy.