Water-Soluble Aggregation-Induced Emission Luminogens with Near-Infrared Emission for Advanced Phototheranostics

The development of water-soluble aggregation-induced emission luminogens (AIEgens) emitting in the near-infrared (NIR) window holds promise for efficient biomedical applications. Nevertheless, synthesizing water-soluble counterparts of NIR AIEgens presents difficulties due to their intrinsic hydrophobic properties. To address this issue, researchers have developed various molecular design strategies to improve the water solubility of NIR AIEgens. The integration of hydrophilic groups and targeting moieties is a crucial aspect of achieving precise phototheranostics. Here, diverse approaches to attain water-soluble NIR AIEgens for biomedical applications are presented, and three commonly used strategies that involve decorating NIR AIEgens with positively or negatively charged groups, hydrophilic chains, and bioactive moieties are elaborated. These rational design strategies are believed to provide solutions for enhancing the water solubility and biological performance of NIR AIEgens in a single action. The remaining challenges and opportunities in this field are also discussed. The aim is to provide new insights into the design of water-soluble NIR AIEgens and inspire more researchers to make significant contributions to this promising research area.