A Clinical Drug as the Three‐Photon Fluorescence Probe for In Vivo Microscopic Imaging of Mouse Kidney

Three-photon fluorescence (3PF) microscopy encounters significant challenges in biological research and clinical applications, primarily due to the limited availability of high-performance probes. We took a shortcut by exploring the excellent 3PF property of berberine hydrochloride (BH), a clinically utilized drug derived from the traditional Chinese medicine, Coptis. Capitalizing on its renal metabolism characteristics, we employed BH for in vivo 3PF microscopic imaging of the mouse kidney. This approach enabled high-resolution structural observation of renal tubules and facilitated the diagnosis of drug-induced acute kidney injury (AKI) based on renal tubule morphology. The analytical capabilities of 3PF microscopy for renal physiology and pathological diagnosis suggest its potential for future clinical applications.