Second Near‐Infrared Window Fluorescence Materials for In Vivo Dynamic Multiplexed Imaging

Abstract Second near‐infrared (NIR‐II) fluorescence imaging has emerged as a breakthrough technology for accurately revealing complex mechanisms in vivo owing to its high sensitivity, deeper tissue penetration, high spatiotemporal resolution, and high throughput. This review provides a comprehensive overview of NIR‐II fluorescence imaging, specifically focusing on the materials used, including single‐walled carbon nanotubes (SWCNTs), quantum dots (QDs), rare‐earth nanoparticles (RENPs), and organic fluorophores (OFs). It details their development, application, and advantageous performance in NIR‐II fluorescence imaging. Furthermore, this review highlights an approach to dynamic multiplexed NIR‐II fluorescence imaging in vivo that enables multitarget detection, providing a powerful tool for accurately and effectively assessing pathological processes and revealing complex biological mechanisms in vivo. Finally, it explores the aspects of translational medicine for NIR‐II imaging, addressing challenges, and future prospects related to material development, detection equipment, and unmet biomedical applications.