Albumin-seeking NIR dyes for high-sensitive imaging of glomerular filtration barrier breakdown

The kidney, vital for metabolic balance, faces risks of severe diseases if dysfunctional. The glomerular filtration barrier (GFB), crucial for blood filtration, disrupts in conditions like diabetic nephropathy or nephritides, resulting in proteinuria or even renal failure. Monitoring GFB integrity is essential for early diagnosis or prognostic monitoring. However, current methods lack effective contrast agents for precise, non-invasive GFB imaging. As near-infrared-II (NIR-II) imaging offers promising imaging quality due to its deep tissue penetration and high resolution/contrast while albumin servers as an efficient biomarker for GFB disruption, developing NIR-II dyes with inherent albumin-targeting moiety, will provide real-time imaging of GFB disruption. Here, we adopt albumin-seeking cyanine dye to high-resolution image endogenous albumin in mouse models, facilitating detecting even mild disruptions with trace proteinuria. Notably, our strategy can determine albuminuria by real time imaging without the need to collect urine. Albumin-seeking dyes also enable fast and accurate quantitative measurement of microalbuminuria from patients. These dyes could revolutionize diagnostics, offering rapid, sensitive in vivo imaging of microalbuminuria and diverse clinical applications.