An alternative model for photodynamic therapy of cancers: Hot-band absorption

The sulfonated aluminum phthalocyanine (AlPcS), a photosensitizer for photodynamic cancer therapy (PDT), has an absorption tail in the near-infrared region (700–900 nm) which is so-called hot band absorption (HBA). With the HBA of 800 nm, the up-conversion excitation of AlPcS was achieved followed by the anti-Stocks emission (688 nm band) and singlet oxygen production. The HBA PDT of AlPcS seriously damaged the KB and HeLa cancer cells, with a typical light dose dependent mode. Particularly, the in vitro experiments with the AlPcS shielding solutions further showed that the HBA PDT can overcome a self-shielding effect benefiting the PDT applications.