Near-infrared theranostics for brain diseases: Design, engineering, and emerging applications

Over the past decades, advancements in fluorophore chemistry and imaging hardware have revolutionized fluorescence-based theranostic technologies in biomedical applications. In particular, near-infrared (NIR) theranostics with exceptionally large tissue penetration depth, a distinctive signal-noise ratio, and significant therapeutic potential, have become a powerful tool, driving breakthroughs in brain disease research. This review mainly offers an up-to-date summary of the advances over the last five years in developing new NIR materials and their applications for brain diseases. First, we overview the brief developmental history of NIR imaging, the material types, the imaging advantages, and the regulatory approaches to improve the photonic properties of fluorescent probes. Then, we summarize the recent developments of NIR imaging for brain tumor diagnosis, cerebrovascular imaging, protein detection, single-cell tracking, surgical navigation, tumor phototherapy, neurodegenerative diseases theranostics, and neuromodulation. Finally, the review concludes with a perspective on the challenges and opportunities associated with NIR theranostic technology, focusing on its future scalable developments in neuroscience. These developments provide a comprehensive mechanistic understanding for customizing the multi-in-one NIR theranostics and inspire more NIR-based photonic solutions for brain diseases, accelerating the progress of NIR material science and biomedical applications.