Herb-Derived Carbon Dots

Herbs possess a long history of medicinal use and abundant pharmacological activities. However, the inherent limitations of their poor bioavailability often restrict their therapeutic efficacy. In recent years, carbon dots (CDs) have shown great potential in biomedical applications owing to their excellent optical properties, good biocompatibility, low toxicity, and small size. Using herbs as precursors to prepare CDs can preserve the "multicomponent, multitarget" characteristics of the crude herbs, enhance and transform their functions through nanoscale effects, offering unique advantages in biomedicine. Quantitative analysis of 121 entries reveals that herb-derived CDs typically exhibit particle sizes of 1-6 nm (mean ≈ 3.4 nm), quantum yields up to 0.67 (mean ≈ 0.11), and broad emission tunability (400-730 nm), with 51 reports including in vivo biosafety testing, all of which showed no obvious toxicity. Based on the latest advances in herb-derived CDs, this review focuses on precursor selection, pretreatment, and synthesis methods. Furthermore, it discusses their applications in biomedicine, bioimaging, and sensing in detail. Finally, a summary and outlook for this significant and promising field are provided. We hope that this review will offer valuable insights for researchers developing herb-derived CDs and contribute to the ongoing modernization and sustainable development of traditional Chinese medicine.