Fig. 1: Design, sensing mechanism, and characterization of NDPs.
From: NIR-II-excited off-on-off fluorescent nanoprobes for sensitive molecular imaging in vivo
Schematic illustration of normal tissue signal of previous works, showcasing (a) “always-on” probes and (b) “off–on” probes (also known as activatable probes or turn-on probes), and (c) this work “off-on-off” probes in vivo. Created in BioRender. Jiajing, G. (2022) BioRender.com/m53h190. d Schematic illustration of low background signal of NIR-II-excited “off-on-off” NIR-II fluorescent probes (NDPs) in vivo. Created in BioRender. Jiajing, G. (2022) BioRender.com/m53h190. e The absorption spectra of ND (1 × 10−6 M) and 2H-ND (1 × 10−6 M) in tetrahydrofuran. (f) The fluorescence spectra of ND and 2H-ND in tetrahydrofuran under 1064 nm excitation. Representative (g) transmission electron microscopy (TEM) and (h) dynamic light scattering (DLS) images of NDPs. The (i) structure stability and (j) photostability (power density of 2 W cm−2) of NDPs. (n = 3 independent samples; mean ± SD).
