Two-photon NIR-responsive carbon dots incorporated into NMOFs for targeted photodynamic therapy

Abstract

In recent years, Photodynamic therapy (PDT) has shown great potential in clinics to treat cancer. Due to the limited depth range of UV or visible laser light penetration, the eradication of solid tumors using traditional photosensitizer is difficult. Here, we report the development of a new NIR active photosensitizer covalently conjugated to nanoscale metal-organic frameworks (NMOFs) for the eradication of deep-seated tumors. This photosensitizer can generate reactive oxygen species (ROS) in the presence of near-infrared light irradiation (980 nm) for PDT. Therefore, we use a strategy to develop two-photon absorbing carbon dots with a fluorescence quantum yield of 13%. The NMOFs are fabricated in the presence of folic acid, which enables them to target cancer cells that overexpress the folate receptor. NMOFs are used as a nanocarrier for CDs and are employed to achieve targeted PDT. This study is the first to observe that carbon dots embedded in NMOF composite could generate singlet oxygen (1O2) under the 980 nm laser light irradiation and also specifically target cancer cells. At a concentration of 100 μg/ml, the nanocomposite demonstrated a 73% rate of cell inhibition. The primary results reported here will show great potential in the future to develop multifunctional carbon dots for targeted two-photon PDT in the presence of higher wavelength light irradiation.