Indocyanine Green Derivative Covalently Conjugated with Gold Nanorods for Multimodal Phototherapy of Fibrosarcoma Cells

A hydrophilic indocyanine green derivative (ICG-Der-02) was covalently doped into mesoporous silica-coated gold nanorods (AuNRs/mSiO₂). The self-synthesized derivative offers one carboxyl functional group on a side chain, which enables ICG-Der-02 to be covalently linked to nanomaterials and reduces the probability of leakage/desorption of the dye. The detection of infrared luminescence around 1270 nm confirmed that ¹O₂ is efficiently generated by the nanocomposite (AuNRs/mSiO₂-ICG-Der-02). Furthermore, a second layer of silica was coated onto the nanocomposite, which then was conjugated with the α_v integrin-targeting cyclic peptide (RGD-4C). The cell tests showed that the resulting nanoconjugate (AuNRs/mSiO₂-ICG-Der-02/RGD-4C) was able to bind preferentially to HT-1080 human fibrosarcoma cells. Due to the synergistic effect of the produced nanoconjugates, a dual-modality photothermal and photochemical therapy was successfully achieved by 808 nm irradiation. Compared to using photothermal or photochemical therapy alone, the dualmodality photothermal/photochemical therapeutic strategy proved to be more damaging to HT-1080 cells and enhanced the effectiveness of photodestruction. Our work presents a novel approach to the multimodal treatment of fibrosarcoma and shows promise for future use in cancer theranostics.