Nanoparticle

Autofluorescence

Biotechnology

Biology

Materials science

Persistent luminescence

Core (optical fiber)

Fluorescence-lifetime imaging microscopy

Preclinical imaging

In vivo

Physics

Nanotechnology

Organic chemistry

Luminescent Measurements

Thermoluminescence

Optics

Near-infrared spectroscopy

Luminescence

Fluorescence

Composite material

Nanomaterials

Chemistry

Lanthanide

Optoelectronics

Nature Nanotechnology

Persistent luminescence is not affected by background autofluorescence, and thus holds the promise of high-contrast bioimaging. However, at present, persistent luminescent materials for in vivo imaging are mainly bulk crystals characterized by a non-uniform size and morphology, inaccessible core–shell structures and short emission wavelengths. Here we report a series of X-ray-activated, lanthanide-doped nanoparticles with an extended emission lifetime in the second near-infrared window (NIR-II, 1,000–1,700 nm). Core–shell engineering enables a tunable NIR-II persistent luminescence, which outperforms NIR-II fluorescence in signal-to-noise ratios and the accuracy of in vivo multiplexed encoding and multilevel encryption, as well as in resolving mouse abdominal vessels, tumours and ureters in deep tissue (~2–4 mm), with up to fourfold higher signal-to-noise ratios and a threefold greater sharpness. These rationally designed nanoparticles also allow the high-contrast multiplexed imaging of viscera and multimodal NIR-II persistent luminescence–magnetic resonance–positron emission tomography imaging of murine tumours. Persistent luminescence is a promising bioimaging technique that is not affected by background autofluorescence, but its in vivo application is challenged by the fact that the materials currently available are activated by high-energy light, with emission in the ultraviolet and visible spectral windows. In this paper the authors engineer X-ray activated, lanthanide-based nanoparticles with a tunable emission in the biologically relevant NIR-II spectral region, which allows high-contrast, multimodal in vivo deep-tissue organ imaging.

X-ray-activated persistent luminescence nanomaterials for NIR-II imaging