检测细胞内的活性氧（ROS）浓度利用的是活性氧检测试剂盒，该试剂盒中的探针DCFH-DA，本身没有荧光但可自由穿过细胞膜，在细胞内可被酯酶水解生成DCFH，该产物不能透过细胞膜，可被细胞内的ROS氧化生成DCF，DCF有荧光，所以我们可以通过检测DCF的荧光强度来检测GA和GA@PDA浸提液对PC12细胞内ROS水平的影响。

The concentration of reactive oxygen species (ROS) in cells is detected using the ROS detection kit. The probe DCFH-DA in the kit does not have fluorescence itself, but can freely cross the cell membrane, and can be hydrolyzed by esterase to generate DCFH in cells. The product cannot cross the cell membrane, but can be oxidized by intracellular ROS to generate DCF, which has fluorescence.Therefore, we can detect the effects of GA and GA@PDA extracts on the ROS level in PC12 cells by detecting the fluorescence intensity of DCF.