Figure 7.

Tissue-penetration study of NIR afterglow luminescence. (a) Afterglow luminescence (upper panel) and fluorescence (lower panel) imaging of semiconducting polymer NPs (SPN) doped with a ¹O₂ sensitizer, silicon 2,3-naphthalocyanine bis(trihexylsilyloxide) (NCBS) to obtain SPNs with a 5% weight percentage (w/w) of NCBS. The thickness of the chicken tissues is defined above the images. (b) Signal-to-background ratios (SBRs) for afterglow luminescence and fluorescence of SPNs containing 5% (w/w) NCBS as a function of tissue depth. *Statistically significant difference between afterglow and fluorescence intensities in SBRs through chicken tissues at 4 cm (n = 3, unpaired t-test (two-tailed), t = 95.47, df = 4, * p < 0.0001). This image has been adapted with permission from Miao et al. [83] © 2017, Springer Nature.