Cu-MOF@TMB Integrated Test Strips for Naked Eye Colorimetric Detection of a Critical Biomarker for Metabolic and Renal Disorders

Uric acid (UA) serves as a vital biomarker for diagnosing metabolic and renal disorders, prompting the need for rapid and selective detection methods. Herein, a new copper-based metal-organic framework (Cu-MOF), formulated as [Cu₂(TCi)₂] [Cu₅(TCi)₂(H₂O)₈(μ₃-OH)₂], was synthesized using Cu(II) ions and tris(2-carboxyethyl) isocyanurate (H₃TCi) as a flexible linker. Comprehensive characterization through PXRD, FTIR, SEM, EDAX, TGA, XPS, BET and elemental mapping confirmed the framework's structural integrity. To enhance sensing performance, the MOF was integrated with 3,3',5,5'-tetramethylbenzidine (TMB), forming Cu-MOF@TMB composites. Among them, Cu-MOF@TMB-1 exhibited the highest sensitivity, achieving a limit of detection (LOD) of 0.941 ppm in aqueous solution, which further improved to 0.235 ppm in model urine and 0.149 ppm in real urine samples. A portable, enzyme-free, test strip-based colorimetric assay enabled rapid, visible detection of UA through a distinct blue color change. This work demonstrates a cost-effective and selective MOF-based sensing platform with strong potential for clinical diagnostics and point-of-care applications.