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 dis-eases.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.