Acceptor Planarization and Donor Rotation Strategy Balances Radiation and Nonradiation Decay for Achieving Highly Efficient Phototheranostic Agents
Developing near-infrared (NIR) organic phototheranostic agents with aggregation-induced emission (AIE) is crucial for precise diagnosis and synchronous cancer treatment by regulating excited-state energy dissipation. However, the distorted molecular configuration of AIE systems poses a challenge to achieving both high fluorescence quantum yield (QY) and large molar extinction coefficient (ε). Herein, a series of donor-acceptor-donor (D-A-D) AIE small molecules with bright NIR emission and high photothermal conversion efficiency (PCE) were developed through an acceptor planarization and donor rotation molecular engineering strategy. Upon encapsulation into water-dispersible nanoparticles (NPs), SVD NPs exhibited strong molar absorptivity (ε = 3.92 × 10^4 M^-1 cm^-1), high QY of 4%, and improved photothermal performance (PCE × ε = 2.2 × 10^4), enabling effective NIR fluorescence imaging-guided phototherapy for successful ablation of subcutaneous tumors. This study offers valuable insights into the simultaneous enhancement of bright NIR luminescence and exceptional photothermal performance in AIE phototheranostic agents, propelling advancements in tumor diagnosis and treatment.