Atomically precise Ag clusters for intelligent NIR-II imaging

Ligand-protected metal clusters are essential in optics, catalysis, and biomedicine due to their unique electronic transfers and rapid renal clearance, but their stability and photostability are still highly challenged. Here, we develop atomically precise Ag29 clusters with 900–1,200 nm emissions that exhibit ultrahigh structural stability for 2 months and distinct photostability for 140 min via Pt single-atom engineering. The density functional theory shows that Ag29 behaves as a molecular-like semiconductor with a direct band gap of 1.3 eV. Meanwhile, the Pt single atom introduces rich 5d states in the highest occupied molecular orbital, leading to a continuous electron supply that ensures high photostability. We acquire numerous images of blood vessels, which enables machine learning to predict high-resolution near-infrared II (NIR-II) images. The NIR-II light sheet microscopy achieves a large field of view and deep-tissue imaging without photobleaching and accurately surveils the pathological progression of intestinal injury at the depth of 2.4 μm.