Recent advances in the development of NIR-II organic emitters for biomedicine

Fluorescence imaging with deep penetration and low auto-fluorescence in the second near-infrared biochannel (NIR-II, 1000–1700 nm) was developed rapidly during the past decades. Organic materials such as organic small molecules and polymers are promising candidates for various biomedical studies owing to their low toxicity and facile chemical modification. Recently, scaffold-structural diversity and multifunctional utilization of NIR-II fluorophores attracted a lot of attentions as the gradually revealing shortcomings of first generation NIR-I organic fluorophores and unbalanced demand between single fluorescence imaging and clinical practice. In this review, organic emitters including NIR-II organic small molecules and polymers are discussed which focus on their multifunctional applications in biomedicine. Furthermore, we raised the current challenges and perspectives of NIR-II organic emitters.