Dual-Interface Hierarchical Assembly of Asymmetric ICG-Lipid Conjugates Enables Finite J-type Aggregation and Two-Stage NIR-II Fluorescence Enhancement

Aggregation-induced quenching severely limits the imaging properties of indocyanine green (ICG), despite its FDA approval and its emission in the near-infrared II (NIR-II) region. Herein, we introduce a dual-interface assembly strategy that orchestrates the sequential assembly of asymmetric ICG-lipid conjugates at lipid and liposome-protein interfaces to achieve two-stage NIR-II fluorescence enhancement. The ICG-sphingosine conjugates without sulfonate groups (ICG-C-Sp) form finite, weakly coupl