Lysosome-targeting NIR ratiometric luminecent upcoversion nanoprobe toward arginine

Near-infrared (NIR) fluorescent sensors have been actively pursued due to organisms exhibiting little autofluorescence in near-infrared regions. Capable of emitting luminesence under 980 nm excitation, upconversion nanoparticles have shown promise as optical agents for in vivo bioimaging. Based on luminescence resonance energy transfer (LRET), a NIR luminescent Arg-nanoprobe was developed by the decoration of upconversion nanoparticles (UCNPs) (NaYF₄:Yb,Er) with organic molecules. The as-developed nanoprobe could quantitatively detect concentrations within the range of 528–1250 μM, and had high sensitiviy (the limit of detection, LOD, being 15.6 μM) and good photostability. Because the probe could target lysosomes, intracellar detection of Arg behavior was demonstrated via upconversion luminescence (UCL) imaging.