Light has profoundly impacted modern medicine and healthcare, with numerous luminescent agents and imaging techniques currently being used to assess health and treat diseases. As an emerging concept in luminescence, aggregation-induced emission (AIE) has shown great potential in biological applications due to its advantages in terms of brightness, biocompatibility, photostability, and positive correlation with concentration. This review provides a comprehensive summary of AIE luminogens applied in imaging of biological structure and dynamic physiological processes, disease diagnosis and treatment, and detection and monitoring of specific analytes, followed by representative works. Discussions on critical issues and perspectives on future directions are also included. This review aims to stimulate the interest of researchers from different fields, including chemistry, biology, materials science, medicine, etc., thus promoting the development of AIE in the fields of life and health.

In this contribution, we propose natural resources as a new source to acquire biocompatible AIEgens.

Carbon dots (CDs) with excellent cytocompatibility, tunable optical properties, and simple synthesis routes are highly desirable for use in optical bioimaging. However, the majority of existing CDs are triggered by ultraviolet/blue light, presenting emissions in the visible/first near‐infrared (NIR‐I) regions, which do not allow deep tissue penetration. Emerging research into CDs with NIR‐II emission in the red region has generated limited designs with poor quantum yield, restricting their in vivo imaging applications due to low penetration depth. Developing novel CDs with NIR‐II emissions and high quantum yield has significant and far‐reaching applications in bioimaging and photodynamic therapy. Here, it is developed for the first time Fe‐doped CDs (Fe‐CDs) exhibiting the excellent linear relationship between 900–1200 nm fluorescence‐emission and pH values, and high quantum yield (QY‐1.27%), which can be used as effective probes for in vivo NIR‐II bioimaging. These findings demonstrate reliable imaging accuracy in tissue as deep as 4 mm, reflecting real‐time pH changes comparable to a standard pH electrode. As an important example application, the Fe‐CDs probe can non‐invasively monitor in vivo gastric pH changes during the digestion process in mice, illustrating its potential applications in aiding imaging‐guided diagnosis of gastric diseases or therapeutic delivery.