IR780-dye loaded gold nanoparticles as new near infrared activatable nanotheranostic agents for simultaneous photodynamic and photothermal therapy and intracellular tracking by surface enhanced resonant Raman scattering imaging.

Due to the good transparency of the human tissue in the biological spectral window, near-infrared (NIR)-dye loaded nanosystems enable more effective light-activated therapy and better contrast imaging with major impact on nanomedicine. Herein, we prepare Pluronic coated gold nanoparticles incorporating the hydrophobic NIR dye, IR780 iodide (GNP-Plu-IR780) to provide water-solubility and stability and demonstrate the proficiency of combining photodynamic and photothermal therapeutic activity with surface-enhanced resonance Raman scattering (SERRS) imaging facility. The potential of GNP-Plu-IR780 to operate as NIR-activatable agents was first assessed in aqueous solution by singlet oxygen generation measurements and monitoring the temperature increase of the nanoparticles. Subsequent in vitro uptake studies by dark field and differential interference contrast (DIC) microscopy reveal massive internalization of GNP-Plu-IR780 by murine colon carcinoma cells (C-26). Moreover, by exploiting the SERRS effect under 785 nm laser excitation we were able to perform intracellular tracking of GNP-Plu-IR780. Finally, NIR irradiation experiments conducted in vitro against C-26 cells show efficient phototherapeutic activity induced by GNP-Plu-IR780 with no dark cytotoxicity. Moreover, when compared to the administration of free drug or non-loaded GNP-Plu, the higher phototherapeutic activity of GNP-Plu-IR780 indicates the occurrence of cooperative synergistic effects by simultaneous photodynamic and photothermal activity.