Self-Luminous Probe with One-Step Energy Conversion from Bioluminescence to NIR-IIb.

Self-luminous probes with near-infrared (NIR) emission are powerful tools for deep-penetration and autofluorescence-free imaging, owing to the joint optimization of both excitation and emission. However, the limited emission wavelength and requirement for multistep energy transfer limit its potency. In this study, we establish the concept of direct wavelength conversion from visible light (VIS) to NIR-IIb using an exquisitely designed sensitizer-activator ion pair. The manipulation of the doping hosts enables a pair of energy levels between the sensitizer and activator. Based on this a class of broadband VIS-responsive nanocrystals with intense NIR-II emission was prepared. The stability and quantum yield (up to 7.4%) of the nanocrystals were further enhanced by ZnS passivation via coherent epitaxial growth. By coupling luciferase, the self-luminous probe can convert bioluminescence to NIR-IIb luminescence (>1500 nm) through a one-step energy transfer. A maximum penetrable thickness of 6 mm was achieved in the porcine tissue model. Collectively, the distinctive photon-conversion performance of this probe offers the prospect of high-resolution labeling of deep-seated lesions. This article is protected by copyright. All rights reserved.