Fig. 2

a Response mechanism of the PEGylated-IONPs to granzyme B. b Construction and in vivo NIR fluorescence images of mice bearing dual skin grafts. c Quantified fluorescent intensities of excised skin grafts. d Normalized urine fluorescence in naive mice, isograft mice, CD8-depleted allograft mice, and allograft mice pre- and post-transplant surgery. Reproduced with permission from ref. [67] Copyright 2019 nature biomedical engineering. e, f The chemical structures and activation forms of AMProN (e) and AMProT (f). g Representative NIRF images of live mice following intravenous injection of AMProN and AMProT 4 days after drug administration. Reproduced with permission from ref. [68] Copyright 2023 Wiley–VCH