Fig. 3: Differences in signal-to-noise ratios and photothermal effects between NIR-II bioluminescence and fluorescence imaging.

a Schematic illustration of optical imaging. b NIR-II fluorescence image (top) and NIR-II bioluminescence image (bottom) under 5 mm chicken breast tissue. Scale bar, 2 mm. c Signal-to-noise ratios of capillaries filled with NIR-II-BPs with different thicknesses of chicken breast tissue for NIR-II fluorescence imaging and NIR-II bioluminescence imaging. Bars represent mean ± s.d. derived from n = 3 independent experiments. d Schematic illustration for thermal effect study on chicken breast tissues. e Photothermal imaging of chicken breast tissue with continuous irradiation under 808 nm (329 mW cm⁻²), 980 nm (726 mW cm⁻²) and 1064 nm (1070 mW cm⁻²) for 30 min. Scale bar, 5 mm. f Temperature variation curves of chicken breast tissue recorded with irradiation of different excitation wavelengths. g Skin temperatures of nude mouse irradiated under 808 nm (329 mW cm⁻²), 980 nm (726 mW cm⁻²) and 1064 nm (1070 mW cm⁻²) after 30 min. Scale bar, 1 cm. h Temperature variation curves of nude mouse skin recorded with irradiation of different excitation wavelengths. Source data underlying f, h are provided as a Source Data file.