An antifouling electrochemical aptasensor engineered with zwitterionic terpolymer and gold nanostars for robust analysis of oxytetracycline in food.

Abstract

Electrochemical sensors still suffer from challenges associated with interference caused by fouling in complex matrices. To address this issue, we designed a tailored high-performance antifouling sensor interface based on a thiol-terminated zwitterionic terpolymer, [P(MPC-CBMA-MAA)-SH, PMCM-SH], by fine-tuning the composition of two zwitterionic moieties, including 2-methacryloyloxyethyl phosphorylcholine (MPC) and carboxybetaine methacrylate (CBMA), along with methacrylic acid (MAA) for post-functionalization. Highly conductive multi-branched gold nanostars (AuNSs) were introduced to assist sensitive assaying. The precise regulation of PMCM-SH enabled to form a dense and stable hydration layer, endowing excellent antifouling performance, which was validated in simulated solutions and food matrices. Molecular dynamics (MD) simulations offered molecular-level insights into its superior hydration capacity. The aptasensor exhibited excellent analytical performance with a low limit of detection (LOD, 2.19 pg·mL-1) and high recoveries of 98.9-106.9% for oxytetracycline (OTC) in milk, eggs, and pork, exhibiting great potential in solving the limitation of fouling for sensor interface.