Atomic Precise Au₁₈ Clusters for NIR-II Accurate Hepatic Ischemia-Reperfusion 3D Visualization

Conventional fluorescence imaging in the visible and first near-infrared (NIR-I, 700-900 nm) windows is limited by tissue scattering and autofluorescence. The second near-infrared (NIR-II, 1000-3000 nm) window offers deeper penetration depth and higher signal-to-noise ratio due to reduced photon scattering. Among the high-performance probes, atomically precise gold clusters emerge as a promising class of materials, as their defined structure can be engineered for enhanced NIR-II emission. Here, we report controllable Au₁₈ clusters for NIR-II bioimaging, which exhibit superior brightness, stability, and biocompatibility. We successfully dope a single Zn atom into the Au₁₈ cluster structure, thereby optimizing optical properties and improving photostability. Zn atom doping shifts the energy levels downward by approximately 1.2 eV and induces local charge redistribution, resulting in enhanced photoluminescence. The Au₁₇Zn₁ clusters exhibit a 4.1-fold NIR-II fluorescence enhancement and high temporal stability with excellent biological safety. Furthermore, Au₁₇Zn₁ shows potential for visualizing liver tissue in mice with hepatic ischemia-reperfusion injury (HIRI). In addition, three-dimensional (3D) imaging of HIRI mice using light-sheet microscopy (LSM) reveals vascular dilation from approximately 120 to 300 µm, clearly delineating the different stages of HIRI. Therefore, Au₁₇Zn₁ shows potential as a tool for HIRI assessment.