Extended Data Fig. 9: In vivo NIR-II persistent luminescence and NIR-II fluorescence imaging of tumours using Nd-PLNPs (NaYF4:1%Nd@NaYF4).
From: X-ray-activated persistent luminescence nanomaterials for NIR-II imaging
a–c, NIR-II PL images (a), NIR-II FL images (b) and optical photos (c) of ultrasmall CT-26 tumours in a living mouse. d, Corresponding intensity profiles of NIR-II PL images in a and NIR-II FL images in b overtime. e, Normalized intensity profiles of NIR-II PL image (t = 10 s) and NIR-II FL image (808 nm laser power: 4 mWcm−2). f, Tumour-to-normal tissue (T/N) ratios of the tumour 2 shown in a and b as a function of time (n = the number of pixels within the corresponding ROI in a and b). Scale bar: 1 cm. Imaging exposure time for PL and FL imaging is 10 s and 0.1 s, respectively. Nd-PLNPs were injected into ultra-small tumors (1.5–3.5 mm) of living mice. NIR-II PL imaging of tumour showed sharper FWHM (0.94-fold for tumour 1, 0.89-fold for tumour 2, and 0.66-fold for tumour 3) than that of NIR-II FL imaging due to reduced background noise without excitation light. Meanwhile, the tumour-to-normal tissue (T/N) ratio recorded from PL imaging reached 437.6 after injection for 10 s, which was ~ 65.3-fold higher than that of NIR-II FL (~ 6.7). Although the T/N ratios decreased with PL signal attenuation, they maintained above ~ 36 over 60 min, which was 7 times higher than the Rose criterion.
