Fig. 2
![Fig. 2](http://media.springernature.com/full/springer-static/image/art%3A10.1186%2Fs12951-022-01402-z/MediaObjects/12951_2022_1402_Fig2_HTML.png)
a Schematic illustration of the synthetic procedure of AuNS@BSA/I-MMP2 NPs and their applications, b TEM image of AuNS@BSA/I-MMP2 NPs, c in vivo NIR fluorescence images of mice bearing A549 tumors after injection of AuNS@BSA/I-MMP2 NPs (excitation = 710 nm, emission = 790 nm), d PA images of AuNS@BSA/I-MMP2 NPs treated mice at different time intervals (excitation = 780 nm). Reproduced with permission from [116]. Copyright ©2019, Elsevier