Electrocatalytic determination of homocysteine using a bimetallic Zn-Ni MOF nanosheets/graphene oxide nanocomposite/ferrocene dicarboxylic acid/ionic liquid modified carbon paste electrode

Abstract

We synthesized the bimetallic zinc-nickel metal–organic framework nanosheets/graphene oxide nanocomposite (Zn-Ni MOF NSs/GO nanocomposite) through a solvo/hydrothermal method. We characterized it utilizing X-ray diffraction (XRD), field-emission scanning electron microscopy (FE-SEM), and energy dispersive X-ray spectroscopy (EDX). Then, a modified carbon paste electrode with the Zn-Ni-MOF NSs/GO nanocomposite, ionic liquid (IL), and ferrocene dicarboxylic acid (FCD) was prepared (Zn-Ni MOF NSs/GO/IL/FCD/CPE) for the voltammetric determination of homocysteine (Hcys). The electrocatalytic performance of the Zn-Ni MOF NSs/GO/IL/FCD/CPE sensor toward Hcys was studied via various voltammetric methods (cyclic voltammetry (CV), differential pulse voltammetry (DPV)) and chronoamperometry. The results of the CV tests demonstrated that the Zn-Ni MOF NSs/GO/IL/FCD/CPE sensor exhibited superior catalytic performance for the oxidation of Hcys within a phosphate buffer solution (PBS, pH of 7.0) compared to other electrodes. This enhanced activity can be attributed to the combined effects of the IL, FCD, and the Zn-Ni-MOF NSs/GO nanocomposite. The designed electrode was utilized to determine Hcys using DPV. Under optimized conditions and parameters, the anodic current response varied linearly with Hcys levels in the ranges of 0.05 to 12.5 and 12.5 to 200.0 μM, achieving a sensitivity of 0.6408 μA μM⁻¹. With this approach, the limit of detection (LOD) was determined to be 0.02 μM. Moreover, the created sensor exhibited good reproducibility, repeatability, and stability. Validation in real samples demonstrated the sensor's practical utility for Hcys detection, yielding excellent recovery rates between 98% and 104.3%. This developed electrochemical sensor shows considerable potential for clinical applications in the detection of Hcys.