Near-infrared-LED photostimulated luminescent nanoprobes based on lanthanide-doped SrS nanocrystals

Near-infrared (NIR) photostimulated luminescence (PSL) nanocrystals (NCs) exhibit deep penetrability and low autofluorescence, recently evoking extensive interest for their application in biosensing. Nevertheless, most of the NIR PSL NCs encounter substantial constraints in biomedicine applications, primarily stemming from the necessity of high-power diode laser stimulation or their larger particle size. Herein, we design a new class of NIR light-emitting diode (LED) PSL NCs based on SrS:Eu2+ NCs, which were coated with SrS shell to improve their stability and photoluminescence (PL) intensity. The trap depth and density of the NCs were further tailored through thermal annealing and Dy3+ co-doping, resulting in efficient NIR PSL with a duration time longer than 2 h by stimulation with an NIR LED in a broad region within 700–1400 nm. Benefiting from their excellent NIR PSL, we showcased the potential of SrS:Eu2+,Dy3+@SrS NCs as sensitive nanoprobes for tumor-targeted imaging in zebrafish with a signal-to-noise ratio of 18.9. These findings demonstrate the significant promise of the proposed SrS:Eu2+,Dy3+@SrS nanoprobes for in vivo bioimaging, which may pave the way for the development of effective NIR PSL nanoprobes for diverse bioapplications in the future.