Fig. 5

In vitro and in vivo demonstration of ROS burst triggered by DT-PNs. a Time-dependent relative level of mitochondrial superoxide for 4T1 cells after diverse treatments within 24 h based on flow cytometry analysis (FCAS). MitoSOX Red was employed as a fluorescent indicator of mitochondrial superoxide. The mean value was calculated by the t test (mean ± s.e.m. n = 3). **p < 0.01, compared with the free CPT group. b Determination of superoxide in mitochondria upon different treatments for 8 h detected by MitoSOX based on FCAS. c Statistical analysis of the mean fluorescence intensity in b. The mean value was calculated by the t test (mean ± s.e.m. n = 3). *p < 0.05, ***p < 0.001, compared with the indicated group. d CLSM imaging of mitochondrial superoxide by MitoSOX staining upon the same treatments in b (scale bar, 20 μm). e In vivo fluorescence imaging of 4T1 tumor-bearing Balb/c mice after intravenous injection with free CPT, NT-PNs, cRGD-PNs, TPP-PNs, and DT-PNs with/without 20 mM NAC or 10 mM Vc for 12 h, and followed by intraperitoneal injection with one ROS probe (Cellular Reactive Oxygen Species Detection Assay Kit, Deep Red Fluorescence), white arrows indicate the tumor sites. f Quantitative analysis for the fluorescence intensity of tumor sites in e. The mean value was calculated by the t test (mean ± s.e.m. n = 3). ***p < 0.001, compared with the indicated group