Simultaneous Imaging and Photodynamic‐Enhanced Photothermal Inhibition of Cancer Cells Using a Multifunctional System Combining Indocyanine Green and Polydopamine‐Preloaded Upconversion Luminescent Nanoparticles

Abstract

AbstractThis work introduces a novel multifunctional system called UPIPF (upconversion‐polydopamine‐indocyanine‐polyethylene‐folic) for upconversion luminescent (UCL) imaging of cancer cells using near‐infrared (NIR) illumination. The system demonstrates efficient inhibition of human hepatoma (HepG2) cancer cells through a combination of NIR‐triggered photodynamic therapy (PDT) and enhanced photothermal therapy (PTT). Initially, upconversion nanoparticles (UCNP) are synthesized using a simple thermal decomposition method. To improve their biocompatibility and aqueous dispersibility, polydopamine (PDA) is introduced to the UCNP via a ligand exchange technique. Indocyanine green (ICG) molecules are electrostatically attached to the surface of the UCNP‐polydopamine (UCNP@PDAs) complex to enhance the PDT and PTT effects. Moreover, polyethylene glycol (PEG)‐modified folic acid (FA) is incorporated into the UCNP‐polydopamine‐indocyanine‐green (UCNP@PDA‐ICGs) nanoparticles to enhance their targeting capability against cancer cells. The excellent UCL properties of these UCNP enable the final UCNP@PDA‐ICG‐PEG‐FA nanoparticles (referred to as UPIPF) to serve as a potential candidate for efficient anticancer drug delivery, real‐time imaging, and early diagnosis of cancer cells. Furthermore, the UPIPF system exhibits PDT‐assisted PTT effects, providing a convenient approach for efficient cancer cell inhibition (more than 99% of cells are killed). The prepared UPIPF system shows promise for early diagnosis and simultaneous treatment of malignant cancers.