A Promising NIR-II Fluorescent Sensor for Peptide-Mediated Long-Term Monitoring of Kidney Dysfunction.

Kidney disease is usually "silent" at the early stage but can lead to severe kidney failure later on. The development of bioimaging probes with rapid distribution and long-term retention in the kidney is significant for the precise diagnosis of renal diseases. Here, a strategy for the peptide-mediated delivery and long-term accumulation (>48 h) of second near-infrared window (NIR-II) fluorophores into the kidney is demonstrated. It is shown that both the hepatic-cleared organic molecules and fast renal-cleared ultrasmall nanoparticles can be retained in the kidney after conjugation to the peptide with high polarity. Moreover, a ROS-responsive activatable bilateral NIR-II sensor was designed based on the kidney targeting peptide, which enables both in vivo long-term kidney monitoring and in vitro urine analysis. The capability of the peptide-based sensor to detect early kidney injury and report on kidney dysfunctional progression is particularly crucial for chemotherapy regimen optimization and timely renoprotective intervention during medication.