Aluminum phthalocyanine and gold nanorod conjugates: the combination of photodynamic therapy and photothermal therapy to kill cancer cells

The sulfonated aluminum phthalocyanines (AlPcSs), popularly used photosensitizers, were linked on the surfaces of gold nanorods (AuNRs) by the electrostatic binding to form AlPcS-AuNRs conjugates, in order to improve the photo-therapy efficiency of cancer cells by combining the photodynamic therapy (PDT) of AlPcSs and the photothermal therapy (PTT) of AuNRs. The AlPcS's fluorescence is two-fold enhanced when they adhered on the surfaces of AuNRs probably due to the surface Plasmon coupling, which would facilitate the AlPcS detection. The fluorescence images show that AuNRs can carry loaded AlPcSs to penetrate into human nasopharyngeal carcinoma cells with a fast speed, achieving the effective intracellular delivery of AlPcSs. The PTT effect of cellular AuNRs alone under the white light irradiation of 50 minutes decreased the cell viability to 77%, and the PDT effect of cellular AlPcS-AuNRs with filtered red light (670-710 nm) irradiation of 50 min lowered the cell viability to 79%. However, with the same white light irradiation of 50 min, the AlPcS-AuNRs destroyed most cells leaving the cell viability to 28%, reflecting a typical synergistic effect on cell killing. These results suggest that the combination of PTT and PDT with AlPcS-AuNRs is a promising strategy for improving the phototherapy of cancers.