A NIR-to-NIR non-emissive rare-earth nanoprobe that specifically lights-up inflammatory condition in vivo

Abstract

Development of exquisitely selective and sensitive HClO/ClO– sensor in living system is of the utmost importance. To achieve near-infrared (NIR)-responsive detection of HClO/ClO–, a new nanoprobe (csUCNP-Cy820) is composed of the ClO–-sensitive Cy820 (energy acceptor), and NaLuF4:20%Yb,1%Tm@NaLuF4 core@shell upconversion nanoparticles (csUCNP, energy donor) capable of emitting NIR upconversion luminescence (UCL) of Tm3+ (800 nm). Through the mechanism of Förster resonance energy transfer (FRET), the UCL emission can be recovered in the presence of HClO/ClO–. The csUCNP-Cy820 nanoprobe is effectively adapted as a precise ClO– detection sensor with a low limit of detection (LoD) of 58 nmol/L in vitro. Moreover, owing to excitation and emission wavelengths both falling within the NIR region, the nanoprobe facilitates high quality imaging in mice models of peritonitis and arthritis, thereby enabling deeper penetration depth for imaging detection in vivo.