Voltammetric immunosensor for selective thyroxine detection using Cu‐MOF@PANI composite.

A label‐free electrochemical immunosensor was fabricated for the detection of thyroxine hormone by immobilizing thyroxine‐specific monoclonal antibody (Ab) onto copper metal‐oxide framework (Cu‐MOF) and polyaniline (PANI) composite modified screen‐printed carbon electrode (SPCE). The Cu‐MOF@PANI@Ab‐modified SPCE was used as a sensing platform. Cu‐MOF and its composite were characterized by field emission scanning electron microscopy (FESEM), Fourier transform infrared spectroscopy, RAMAN spectroscopy, X‐ray diffraction, cyclic voltammetry (CV), and differential pulse voltammetry (DPV). The immunosensor possessed a dynamic linear range (10–105 pM) with a low limit of detection (LOD) of 0.33 pM (0.25 pg/mL) for CV and 0.17 pM (0.13 pg/mL) for DPV. The evaluation study of immunosensor displayed a good analytical recovery of ≥90%, when different concentrations of thyroxine were added in the serum sample. In addition, to determine the reproducibility for working electrode between and within batch, the relative standard deviation calculated were 3.87% and 6.04%, respectively, and represent its good reproducibility. The immunosensor retained 90% of its initial activity after its regular use for 40 days, while being stored at 4 °C. [ABSTRACT FROM AUTHOR]