This study discusses the determination of thyroxine hormone in blood serum samples by a novel MOF composite electrode. The used MOF was Zn(BTC)-(MOF) which was constructed from 1,3,5-benzenetricarboxylic acid ligand (BTC) and zinc ions in DMF solvent. Using cysteine as the linker, the MOF was plated on the surface of a gold electrode, formerly covered by a layer of gold nanoparticles immersed in conductive polymer polypyrrole (PPy). Different analytical methods, such as FTIR, XRD, SEM, EIS, CV, and BET, were utilized to investigate the morphology and performance of the prepared materials. The modified electrode exhibited excellent electrocatalytic ability to reduce thyroxine without interference from common coexisting substances such as different salts. The fabricated electrode has been successfully used to determine thyroxine in a linear concentration range of 10–210 nM with a detection limit of 8 nM.
