Fig. 6: In vivo NIR-II FL and PA imaging of hypoxic tumor.

a Representative in vivo NIR-I FL (excitation: 530 nm, emission: 600 nm) and NIR-II FL (excitation: 730 nm, emission: 1000 nm) images obtained from 4T1 tumor-bearing mice at various time points following intratumoral injection of BC@Z-M. As control, BC@Z-M was also administered via subcutaneous injection into the left flanks of mice (without tumor inoculation). Yellow arrows denote the tumor, while white arrows indicate the healthy control flank. b Ratiometric turn-on FL of tumor and healthy sites of 4T1 tumor-bearing mice after injection of BC@Z-M for different time based on (a) (n = 3 mice). c Representative microscopic images of tissue sections showing the NIR-II FL activation of BC@Z-M and elevated hypoxia, as indicated by HIF-1α staining, in the tumor tissue when compared to healthy tissue. Scale bar: 100 µm. d Representative NIR-II FL images and (e) corresponding tumor NIR-II FL intensity of 4T1 tumor-bearing mice after i.v. injection of BC@Z or BC@Z-M for different time (n = 3 mice). f Representative NIR-II FL images and (g) corresponding NIR-II FL intensity of major organs and tumors from mice at 24 h post i.v. injection of BC@Z or BC@Z-M (n = 3 mice). h Representative PA images and (i) corresponding PA intensity of tumor site in 4T1 tumor-bearing mice after i.v. injection of BC@Z or BC@Z-M for various time (n = 3 mice). Scale bars: 1 mm. All data are presented as mean ± SD. For (a, c, d, f, h), experiment was repeated three times independently with similar results. Statistical significance was determined using two-tailed Student’s t-test. Source data are provided as a Source Data file.