Iodine-doped carbon dots for fluorescence/computed tomography imaging and photodynamic therapy of tumor cells

Theranostic nanoagents have attracted considerable research interest due to their fascinating capability to simultaneously offer therapeutic and diagnostic functions. Here, novel iodine-doped carbon dots (I-CDs) were fabricated from arginine and iohexol via a facile hydrothermal strategy. I-CDs exhibited excellent stability and biocompatibility. Owing to a high quantum yield of 18.67%, the prepared I-CDs were suitable for the fluorescence imaging of tumor cells. Subcellular localization analysis showed that I-CDs were mostly distributed in lysosomes and mitochondria. Notably, the I-CD-treated A549 and HeLa cells simultaneously exhibited outstanding intracellular nitric oxide (NO) and reactive oxygen species (ROS) release capacities under an LED lamp illumination. The NO generation ability of I-CDs originated from the arginine moieties on their outer surface. The outcomes of in vitro investigations indicated that I-CDs were an effective nanophotosensitizer for the photodynamic therapy (PDT) of A549 and HeLa cells. Computed tomography (CT) scan data revealed that the Hounsfield unit (HU) value of I-CDs surpassed that of iohexol. Thereafter, the obtained I-CDs were successfully applied for performing the fast CT contrast imaging of mouse kidneys and bladders (within 1 minute); notably, I-CDs displayed negligible histopathological and hemolytic toxicity. I-CDs showed potential in the fields of fluorescence/CT bimodal imaging and PDT.