Non-Enzymatic Electrochemical Sensor Based on ZIF-67 and Mwcnts-ZIF-67 Nanocomposites for Detection of Uric Acid in Human Urea

Abstract

Metal-Organic Frameworks (MOFs) have much interest in the catalytic research community but are less attracted by the sensor society for their poor conductivity. In the present work, we report a novel Zeolitic Imidazolate Framework-67 (ZIF-67) and MWCNT’s-ZIF-67 nanocomposites based on non-enzymatic electrochemical sensors for sensing uric acid in human urea. The conductivity and binding affinity of ZIF-67 are improved by the addition of MWCNTs. Initially, ZIF-67 powders were prepared by facile in-situ synthesis method and then the MWCNTs were introduced into ZIF-67 powders. To achieve better bonding between the carbon and the ZIF-67, MWCNT’s functionalized to attach hydroxyl, carboxyl, and carbonyl groups on the surface of the carbon tubes. The obtained nanopowders were spectroscopically analyzed by using X-ray Diffraction (XRD), Fourier Transform Infrared (FT-IR) spectroscopy, FESEM, and Raman analysis. The MWCNTs-ZIF-67 modified electrode offered the detection limit of uric acid with 1.18 µM and a sensitivity of 97.9 nA µM-1. The sensitivity was performed within two seconds with a linear response (R2=0.99). Fifteen repeated cyclic voltammetric responses were recorded to 0.1M of uric acid to analyze the stability and reproducibility of the electrode. All the sensor responses were determined in comparison with ZIF-67 with MWCNT-ZIF-67 modified electrode performance. In the present work, the catalytic MOFs with low conductivity was modified with MWCNTs and used for ultra-fast and highly-sensitive sensing of uric acid. Keywords: ZIF-67, MWCNTs, Modified Electrode, Uric Acid, and Functionalization