Photostable Iodinated Silica/Porphyrin Hybrid Nanoparticles with Heavy-Atom Effect for Wide-Field Photodynamic/Photothermal Therapy Using Single Light Source

Physical therapies including photodynamic therapy (PDT) and photothermal therapy (PTT) can be effective against diseases that are resistant to chemotherapy and remain as incurable malignancies (for example, multiple myeloma). In this study, to enhance the treatment efficacy for multiple myeloma using the synergetic effect brought about by combining PDT and PTT, iodinated silica/porphyrin hybrid nanoparticles (ISP HNPs) with high photostability are developed. They can generate both 1O2 and heat with irradiation from a light-emitting diode (LED), acting as photosensitizers for PDT/PTT combination treatment. ISP HNPs exhibit the external heavy atom effect, which significantly improves both the quantum yield for 1O2 generation and the light-to-heat conversion efficiency. The in vivo fluorescence imaging demonstrates that ISP HNPs, modified with folic acid and polyethylene glycol (FA-PEG-ISP HNPs), locally accumulate in the tumor after 18 h of their intravenous injection into tumor-bearing mice. The LED irradiation on the tumor area of the mice injected with FA-PEG-ISP HNPs causes necrosis of the tumor tissues, resulting in the inhibition of tumor growth and an improvement in the survival rate.