A Label-Free Molecularly Imprinted Electrochemical Sensor Based on MXene Nanosheets Modified by Gold Nanoparticles for Sensitive and Selective Detection of Homocysteine

A label-free molecularly imprinted electrochemical sensor (MIECS) based on electropolymerized molecularly imprinted polymer (MIP) was developed for the determination of homocysteine (Hcy) in serum for the first time. MXene@AuNPs with layered structure was synthesized on the electrode by modifying MXene with gold nanoparticles (AuNPs). MIP based on dopamine hydrochloride (DA) were electropolymerized onto the surface of MXene@AuNPs modified electrode by molecular docking and quantum chemical calculations for specific recognition of Hcy. MXene@AuNPs as a carrier for immobilizing MIP steadily enhances the conductivity of the electrode (about 4.2-fold) and plays a crucial part in improving the detection sensitivity of MIECS. The results showed that the current response linearly decreased with the increasing concentration of Hcy in the detection range from 1 × 10⁻¹³ to 1 × 10⁻⁵ mol l⁻¹, the limit of detection (LOD) and limit of quantification (LOQ) of 11.81 fmol l⁻¹ and 39.49 fmol l⁻¹, respectively. With favorable selectivity, stability, reproducibility and ruggedness, the developed MIECS was applied to the determination of Hcy in human serum samples with recoveries of 87.83%-92.58%. The proposed strategy has potential application for disease surveillance.