Improving the Stability of Cysteine Molecularly Imprinted Electrochemical Sensors by Optimizing Functional Monomers and Polymerization Methods Improving the Stability of Cysteine Molecularly Imprinted Electrochemical Sensors by Optimizing Functional Monomers and Polymerization Methods

Abstract

Cysteine (Cys) is an important amino acid widely involved in immune function, metabolic regulation and clinical diagnosis. However, traditional Cys detection methods suffer from complex operation, high cost and poor specificity. The ability of molecularly imprinted electrochemical sensors (MIECS) to precisely identify and enrich Cys in complex environments is attributed to their high selectivity and structural specificity, and the stability of these sensors is significantly influenced by the choice of functional monomers and polymerization techniques. The study focused on evaluating the stability of MIP produced using four widely utilized functional monomers, including o-phenylenediamine (OPD), o-aminophenol (OAP), dopamine (DA), and methacrylic acid (MAA). MAA, which performed the best, was chosen as the functional monomer, and three polymerization techniques were refined: electropolymerization, in-situ polymerization, and precipitation polymerization. Consequently, on the surface of glassy carbon electrodes, MXene-Au nanocomposites were modified, choosing MAA as the functional monomer, Cys as the template, ethylene glycol dimethacrylate (EDGMA) as the cross-linking agent, and 2,2'-azobisisobutyronitrile (AIBN) as the initiator, and MIP was prepared by precipitation polymerization method. With a broad linear range of 0.1-20 μM and a low detection limit of 0.041 μM, the optimized MIECS also demonstrated excellent stability, reproducibility, and resistance to interference. The recoveries of 95.4%~104.3% in spiked serum testing demonstrated high accuracy and reliability. The newly developed MIECS offers an enhanced and reliable approach for the detection of Cys, ensuring greater stability and precision compared to existing methods. This advancement provides a more consistent and accurate solution, facilitating improved detection performance in various applications.

Keywords: Cysteine, Functional monomer, Polymerization method, MXene-Au, Molecularly imprinted electrochemical sensors