NIR‐II cyanine@albumin fluorophore for deep tissue imaging and imaging‐guided surgery

Abstract The near‐infrared (NIR)‐II bioimaging technique is highly important for both diagnosing and treating life‐threatening diseases due to its exceptional imaging capabilities. However, the lack of suitable NIR‐II fluorescent probes has hindered their widespread clinical application. To address this issue, the binding of albumin to cyanine dyes has emerged as a practical and efficient method for developing high‐performance NIR‐II probes. Cyanine dyes can bind with exogenous and endogenous albumin through either covalent or noncovalent interactions, serving various purposes. The resulting cyanine@albumin (or albumin@cyanine) fluorophores offer significant advantages, including strong brightness, excellent photostability, good biosafety, and a long‐term, high‐resolution imaging window. Cyanine dye in situ binding with endogenous albumin can also enhance the targeting imaging capability. This review provides a summary of the interaction mechanism, performance enhancement, tumor‐targeting feature, and in vivo imaging applications of the cyanine@albumin fluorophores. These advancements not only highlight the unique characteristics of cyanine@albumin fluorophores in preclinical research but also emphasize their potential for clinical diagnosis.