Switching between upconversion luminescence imaging and therapy in vitro enabled by NIR excitation modulation of nanocomposites

Herein, we designed and synthesized a theranostics-integrated nanocomposite capable of switching between upconversion luminescence imaging and photothermal therapy (PTT)/photodynamic therapy (PDT)/NO gas therapy by changing the wavelength of near-infrared light irradiation. L-Arginine (L-Arg) and indocyanine green (ICG) were encapsulated within mesoporous polydopamine layers coated on upconversion nanoparticles (UCNPs) to obtain the final nanocomposite UCNPs@mPDA/ICG@L-Arg (named UPIL). Under 980 nm irradiation, UPIL exhibits excellent performance in upconversion luminescence imaging. Meanwhile, upon 808 nm irradiation, UPIL not only produces thermal energy for PTT but also directly generates reactive oxygen species for effective PDT, achieving a synergistic effect of PTT/PDT. Furthermore, ICG in UPIL can serve as an oxidant, reacting with L-Arg to produce NO for gas therapy, which can also improve the PDT effect through the generated NO gas. Notably, the simple and effective switching between imaging (excited at 980 nm) and therapy (irradiated at 808 nm) can be achieved by altering the exciting wavelength of the nanocomposite. This orthogonal mode minimizes damage to normal tissue cells. Hence, this versatile nanocomposite platform, designed for near-infrared light-driven upconversion luminescence imaging and tri-modal synergistic therapy, holds the potential for imaging-mediated synergistic therapy, showcasing promising prospects for tumor treatment.