FITC was used as a fluorescent marker to label nanoparticles, and the cellular uptake of FITC-labeled CK-Ngs was qualitatively analyzed using a confocal laser scanning microscope (CLSM). A549 cells were seeded in a special laser confocal culture dish (NEST, Wuxi, China) at a density of 3 × 104, and incubated at 37 °C. Remove from the incubator at a specific time point, wash with PBS three times, incubate with 4% paraformaldehyde for 15 min, and then wash with PBS. The nuclei were stained with 2 μg/mL DAPI for 15 min and washed with PBS. Finally, the imaging of the cells was observed by confocal laser scanning microscopy (CLSM, Olympus Fluoview FV-1000, Tokyo, Japan).