Fig. 3: Comparison of in vivo NIR-II fluorescence imaging upon a bright background and multi-channel imaging of mice.

a Simulated images in 1300–1400, 1400–1500, 1500–1700, 1700–1880 and 1880–2080 nm of the line source above a rectangular background (depth = 1.3 mm) through a routine biological tissue of 1 mm thickness, where the absorption coefficient of water was considered as the tissue absorption coefficient and the setting of tissue scattering coefficient could be found in the “Methods” section. b Fluorescence intensity profiles on the cross-section of the simulated samples above the rectangular backgrounds. c SBR analysis of the simulation results in (a). n = 3 positions were randomly selected for analysis, data are presented as mean ± SD. d SSIM analysis of the simulation results in (a). Whole-body fluorescence imaging of the same mouse in e 1300–1400 nm, f 1400–1500 nm, g 1500–1700 nm, h 1700–1880 nm and i 1880–2080 nm bands. Scale bars: 10 mm. j Cross-sectional fluorescence intensity profiles along the red dashed lines of the blood vessels in (e–i). k SBR analysis of the imaging results in (e–i). l The perception-based image quality evaluator (PIQE) analysis of the liver areas highlighted by the blue boxes in (e–i). m Fluorescence images of the centrifuge tubes containing 1450QD and 1700QD in 1400–1500 and 1880–2080 nm bands. n–p In vivo dual-channel fluorescence imaging of mice. n An abdominal image of mouse intraperitoneally injected with 1450QD. o A vascular image of mouse intravenously injected with 1700QD. p The merged image of (n, o). Scale bars: 10 mm.