The rational design of high-performance fluorescent materials for cancer targeting in vivo is still challenging. A unique molecular design strategy is presented that involves tailoring aggregation-induced emission (AIE)-active organic molecules to realize preferable far-red and NIR fluorescence, well-controlled morphology (from rod-like to spherical), and also tumor-targeted bioimaging. The shape-tailored organic quinoline-malononitrile (QM) nanoprobes are biocompatible and highly desirable for cell-tracking applications. Impressively, the spherical shape of QM-5 nanoaggregates exhibits excellent tumor-targeted bioimaging performance after intravenously injection into mice, but not the rod-like aggregates of QM-2.

The design of bright NIR-II luminescent nanomaterials that enable efficient labelling of proteins without disturbing their physiological properties in vivo is challenging. We developed an efficient strategy to synthesizebright NIR-II gold nanoclusters (AuN Cs) protected by biocompatible cyclodextrin (CD). Leveraging the ultrasmall sizeo fA uN Cs (< 2nm) and strong macrocycle-based host-guest chemistry, the as-synthesized CD-AuN Cs can readily label proteins/ antibodies.M oreover,t he labelled proteins/antibodies enable highly efficient in vivo trackingd uring blood circulation, without disturbing their biodistribution and tumor targeting ability,thus leading to asensitive tumor-targeted imaging. CD-Au NCs are stable in the harsh biological environment and show good biocompatibility and high renal clearance efficiency.T herefore,t he NIR-II biolabels developed in this study provideapromising platform to monitor the physiological behavior of biomolecules in living organisms.

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