An NAG-Activatable Glow-Type Chemiluminescent Probe for Sensitive and Early Diagnosis of Acute Kidney Injury through Urinalysis

The current clinical diagnostic criteria for acute kidney injury (AKI) are based on the evaluation of changes in serum biomarkers (sCr, BUN) and urine output, which are insensitive and typically do not show significant differences until the middle to late stages, thereby hindering the time diagnosis of AKI. Herein, we report an N-acetyl-β-d-glucosaminidase (NAG)-activatable glow-type chemiluminescent probe (CL-NAG) for sensitive detection of urinary NAG and early diagnosis of AKI. CL-NAG was designed and synthesized by incorporating N-acetyl-β-d-glucosamine into the phenoxy-dioxetane scaffolds through a self-immolative linker. Molecular docking calculations predicted a strong interaction between CL-NAG and the catalytic cavity of the NAG enzyme. CL-NAG exhibited high detection sensitivity (LOD = 0.042 U/L) for NAG activity, low autofluorescence interference, and an extremely high signal-to-noise ratio (1628-fold). Furthermore, using this probe, we achieved not only the imaging detection of NAG in HUVEC and HK-2 cells but also the quantitative detection of NAG activity in the urine of an AKI mouse model at different time points. Most importantly, CL-NAG successfully identified 19 positive and 149 negative samples out of 168 clinical urine specimens, proving a high consistency rate of 95.24% compared with clinical biochemical methods. This research demonstrates the sensitive urinary NAG detection ability of CL-NAG and suggests the enormous clinical application potential of CL-NAG in the early diagnosis of AKI.