Bright and Stable NIR-II J-Aggregated AIE Dibodipy-Based Fluorescent Probe for Dynamic In Vivo Bioimaging.

Organic dyes emitting in the second near-infrared (NIR-II, 900-1700 nm) window, with high molar extinction coefficients (MEC) and quantum yields (QY) in aqueous, are essential for in vivo bioimaging and biosensing. In this work, we developed a dibodipy-based aggregation-induced emission (AIE) fluorescent probe, THPP, to meet this aim. THPP exhibits a high MEC and has intensified absorption and emission in J-aggregated state, which significantly enhance the fluorescence intensity (≈55 folds) and extend the maximal absorption/emission wavelengths to 970/1010 nm in NIR-II region. Based on the bright THPP, imaging with a high frame rate (34 frames per second) at a deep "valid penetration depth" up to 6 mm can be achieved. This enabled simultaneous and dynamic imaging of vasculatures and deep tissues. Besides, we succeeded in monitoring the respiratory rate of acute-lung-injury mice and tracing the collateral circulation process with a high frame rate.