Dual Near-Infrared-Emissive Luminescent Nanoprobes for Ratiometric Luminescent Monitoring of ClO– in Living Organisms

The difficulty of near-infrared (NIR) ratiometric detection imaging lies in the lack of high-efficiency NIR probes and the overlapping interference between two emission peaks. To achieve more accurate detection in living organisms, dual NIR-emissive luminescent nanoprobes were designed under the same excitation at 808 nm. The Er³⁺ ion-doped nanoparticles were employed as a reference with their fluorescence emission at 1525 nm. Meanwhile, a cyanine dye molecule (Cy925) was combined on the surface of nanoparticles as the ClO^- recognition site with its NIR emission at 925 nm. The ratiometric nanoprobe relied on the ratio of aforementioned two separated NIR peaks ( I_925nm/ I_1525nm), featuring deeper imaging penetration depth and low autofluorescence. This nanoprobe was verified to be sensitive and highly selective to ClO^- through photoluminescence titration. The in vitro detection experiment developed reasonable work curves, guaranteeing that we can detect the change in concentration of ClO^- in mice limbs with arthritis through in vivo imaging experiments.