Binuclear iridium(iii) chloro-bridged complex as a selective luminescent probe for human serum albumin: sensing studies in rat and human urine.

Human serum albumin (HSA) is a key biomarker for the diagnosis of chronic kidney disease (CKD) because it reflects disease severity, progression, and patient outcomes. Dichloro-bridged complexes of iridium(iii) are well-known intermediates for the preparation of cyclometalated complexes of iridium(iii). Several reports have shown that cyclometalated iridium(iii) complexes serve as probes for HSA sensing. There is no report in which the iridium(iii) chloro-bridged complexes are utilised as probes for biomarker sensing. In this report, for the first time, we utilised the dichloro-bridged iridium(iii) complex [Ir(ppy)2Cl]2 (ppy = 2-phenylpyridine) (M1), an intermediate species obtained during the synthesis of a cyclometalated mononuclear iridium(iii) complex, which shows turn-on HSA sensing. The complex binding site in HSA was substantiated by a docking study and a drug competitive study. The complex M1 binds to HSA in the mononuclear form, as evidenced by docking and HRMS analysis. The scope of the complex in practical application was validated by albumin detection in urine samples from rats and CKD patients. The complex can detect 0.02 mg dL-1 of HSA in urine samples. The results are validated against the ELISA test and pathology lab (ARKRAY's AUTION Sticks) results.