Ultrasound-Activated Near-Infrared-II Afterglow Luminescence for Precise Cancer Imaging

Afterglow fluorescence imaging has been extensively assessed in ultrasensitive bioimaging. Since it eliminates the need for real-time excitation light and thereby circumvents the autofluorescence background of tissue, it holds tremendous potential in accurate biomedical imaging. However, current afterglow probes are rare and emit light only in the visible to near-infrared (NIR) range, which is inadequate for <i>in vivo</i> imaging. To resolve this issue, an ultrasound (US)-activated NIR-II afterglow luminescence probe (NPs-Ce4-SN) emitting afterglow luminescence with a peak at ∼1100 nm was developed. This peak is nearly 400 nm red-shifted compared with other reported afterglow probes. Of note, after US termination, NPs-Ce4-SN undergoes energy transformation to produce ¹O₂ and subsequently undergoes internal oxidation-reduction reaction to produce NIR-II afterglow, generating high signal-to-noise ratio and high-penetration depth imaging. <i>In vitro</i> and <i>in vivo</i> NIR-II afterglow imaging experiments revealed that NPs-Ce4-SN has good biocompatibility and deep tissue penetration depth, suggesting a diagnostic strategy for <i>in vivo</i> tumor imaging with a high signal-to-noise ratio.