Near-infrared luminescence from double-perovskite Sr₃Sn₂O₇:Nd³⁺: A new class of probe for in vivo imaging in the second optical window of biological tissue

抄録

Inorganic phosphors that emit near-infrared (NIR) light are highly valued as fluorescent probes for in vivo imaging of biological tissue. NIR-imaging, however, is limited by the paucity of probes that emit over the NIR-II window (1000–1400 nm). We are interested in exploring the potential of double-layered perovskite structures harboring lanthanide ions as NIR-II fluorescent probes. In this report, we describe the synthesis, and characterization of the photoluminescence, afterglow and thermo-luminescence of Nd³⁺-doped Sr₃Sn₂O₇ together with an analysis of its structural properties. Sr₃Sn₂O₇:Nd³⁺ has a double-layered perovskite structure with oxygen octahedral tilt and rotation, which leads to an intense NIR-II luminescence from 4f–4f transition in Nd³⁺ ions; the intensity of NIR-II photoluminescence of Sr₃Sn₂O₇:Nd³⁺ is 10² times higher than that of an ordinary perovskite structure, namely SrSnO₃:Nd³⁺. Moreover, we show the intra-layer planar defect in Sr₃Sn₂O₇:Nd³⁺ contributes to the long-lived NIR-II afterglow. Finally, we show time-resolved imaging of the long-lived NIR-II fluorescence of Sr₃Sn₂O₇:Nd³⁺ generate high-contrast images of probes embedded within a model tissue.