Structural and Functional NIR-II Fluorescence Bioimaging in Urinary System via Clinically Approved Dye Methylene Blue

Accurate structural and functional imaging is vital for the diagnosis and prognosis of urinary system diseases. Fluorescence bioimaging in the second near-infrared spectral region (NIR-II, 1000–1700 nm) has shown advantages of higher spatial resolution, deeper penetration, and finer signal-to-background ratio (SBR) compared to the conventional fluorescence imaging methods but limited to its clinical inapplicability. Herein, we first report in vivo NIR-II fluorescence imaging of the urinary system enabled by a clinically approved and renal excretable dye methylene blue (MB), which cannot only achieve clear invasive/non-invasive urography but also noninvasively detect renal function efficiently. These results demonstrate that MB assisted NIR-II fluorescence imaging holds a great promise for structural and functional imaging of the urinary system both clinically and preclinically.