The near‐infrared autofluorescence fingerprint of the brain

The brain is a vital organ involved in most of the central nervous system disorders. Their diagnosis and treatment require fast, cost‐effective, high‐resolution and high‐sensitivity imaging. The combination of a new generation of luminescent nanoparticles and imaging systems working in the second biological window (near‐infrared II [NIR‐II]) is emerging as a reliable alternative. For NIR‐II imaging to become a robust technique at the preclinical level, full knowledge of the NIR‐II brain autofluorescence, responsible for the loss of image resolution and contrast, is required. This work demonstrates that the brain shows a peculiar infrared autofluorescence spectrum that can be correlated with specific molecular components. The existence of particular structures within the brain with well‐defined NIR autofluorescence fingerprints is also evidenced, opening the door to in vivo anatomical imaging. Finally, we propose a rational selection of NIR luminescent probes suitable for low‐noise brain imaging based on their spectral overlap with brain autofluorescence.