Figure 8 The fluorescence imaging analysis for treating SKOV3 cells with coumarin 6-loaded beta-CD nanocage in acidic environment for 3 h and 6 h (a), reduction environment for 3 h and 6 h (b) and normal physiological environment for 3 h and 6 h (c) respectively.
3.5 Flow cytometry analysis of coumarin 6-loaded beta-CD nanocage
The beta-CD nanocage, containing dual-dynamic covalent bonds based on imine and disulfide, played a critical role in controlling drug release. Maintaining the superior performance of beta-CD with specific release properties remains a driving force for further exploration. Therefore, further evidence from flow cytometry analysis was employed. Similar to cell fluorescence imaging, tumor cells were treated with upregulated acidity, upregulated GSH, or left untreated before flow cytometry analysis. As shown in Figure 9, the relative fluorescence intensity increased from untreated tumor cells to GSH-treated tumor cells and further to acid-treated tumor cells at 3 h. Over time, the fluorescence intensity of each group continued to increase, with the variation becoming more significant. The maximum fluorescence enhancement in acid-treated tumor cells was more than 2-fold compared to untreated tumor cells. This comparative analysis of fluorescence intensity confirmed that the imine and disulfide bonds in the beta-CD nanocage played a key role in drug release. Furthermore, the acidic and reductive tumor microenvironment acted as a driver for a controlled drug release pathway.