Functionalized MXene fiber electrode for the electrochemical sensing of urinary ammonia

The development of technologically advanced fiber-based flexible microelectrodes has been of extensive research interest in healthcare systems because of their unique construction and synergistic effect on multifunctional properties.In this work,we constructed functional MXene fiber(MXF)by a simple and versatile wet spinning method,and then,a well-aligned ZIF-67 nanoarray was grown in situ on the surface.Using the chemical vapor deposition(CVD)method,carbon nanotubes(CNTs)were produced on MXF via the pyrolysis of ZIF-67 and melamine.Finally,Pt nanoparticles were electrodeposited on the CNTs forest,and a Pt@CNTs/MXF electrode was obtained.Owing to the plethora of surface active sites and the synergistic effects between MXene,CNTs,and Pt nanoparticles,the as-fabricated fiber electrode enabled the precise detection of ammonia under alkaline conditions via differential pulse voltammetry(DPV),which exhibited a linear range of 0.1μM–10 mM and a detection limit of 73.2 nM.Due to their good performance in ammonia detection,Pt@CNTs/MXF electrodes could be adopted to determine the ammonia concentration in urine for clinical estimation,which provides a practical approach for the diagnosis of urinary ammonia-associated diseases.