Investigation of the bioactivity and fluorescence imaging of multicellular tumor spheroid targeted labelling with CdSe/ZnS quantum dots

Multicellular tumor spheroids are experimental models between animals and 2D cells. It can not only combine with animal experiments to obtain more detailed experimental data to reduce the number of experimental animals, but also can simulate better the tumor microenvironment of solid tumors. Although a variety of multicellular tumor spheroids had been developed, the multicellular tumor spheroids labelling with fluorescence quantum dots were rarely studied. Herein, folic acid-modified CdSe/ZnS quantum dots with size 5.98 ± 0.31 nm were prepared and characterized the properties of fluorescence, stability, and anti-photobleaching. A low-speed centrifugation was used to induce aggregation of the suspended colon cancer cells HCT116 labelled with quantum dots, and the aggregated cell was cultured to form 3D cell spheroids. The changes in fluorescence and biological activity of 3D cell spheroids and the position of quantum dots in cells were further studied. The results showed that cells labelled with quantum dots can form intact cell spheroids and maintain high fluorescence intensity and bioactivity.