A Targeted Activatable NIR‐IIb Nanoprobe for Highly Sensitive Detection of Ischemic Stroke in a Photothrombotic Stroke Model

Abstract Ischemic stroke is a devastating disease resulting in high morbidity and mortality. To date, its early diagnosis still faces challenges. Herein, an efficient detection strategy is proposed, in which a targeted activatable NIR‐IIb nanoprobe (V&C/PbS@Ag 2 Se) is constructed for in vivo highly sensitive detection of early ischemic stroke in a photothrombotic stroke model. At first, the fluorescence of V&C/PbS@Ag 2 Se displays an “off” state due to the competitive absorption of excitation irradiation between Cy7.5 fluorophores and PbS@Ag 2 Se quantum dots (QDs). Upon intravenous injection, the V&C/PbS@Ag 2 Se quickly accumulates in the lesion regions based on VCAM1 binding peptide target to the inflamed vascular endothelium of ischemic stroke. Later, the nanoprobes can be rapidly activated via Cy7.5 oxidation by peroxynitrite (ONOO − ), the prodromal biomarker of ischemic stroke, instantly illuminating the lesion regions. Such a targeted activatable strategy offers a favorable approach for in vivo early real‐time assessment of ischemic stroke, which can be expanded to other diseases as a general mothed for in vivo precise diagnosis.