A novel ratiometric electrochemical aptasensor based on β-cyclodextrinylated graphene and Fc/β-CD host–guest recognition for ultrasensitive detection of zearalenone

Abstract

Zearalenone (ZEN) is a carcinogenic mycotoxin commonly found in grains, cereals, and dairy products, posing cancer risks to humans and animals. Chronic high-dose ZEN exposure can cause liver disease, immunosuppression, kidney damage, and tumorigenesis. Sensitive and efficient ZEN detection is therefore essential for protecting human and animal health. To meet the need for sensitive, selective, and low-cost mycotoxin sensors in real food samples, we developed a novel ratiometric electrochemical aptamer sensor for ZEN detection. The sensor design utilizes β-cyclodextrin-functionalized graphene (CG) to effectively enhance electron transfer efficiency, combined with host–guest recognition between ferrocene (Fc) and β-cyclodextrin (β-CD), as well as Au–S covalent bonding. The 5′-SH and 3′-MB-modified dual-labeled ZEN aptamer (MB-Apt-SH) was immobilized via β-CD/Fc inclusion, with signal amplified by AuNPs binding to –SH. Without ZEN, the aptamer stays on the electrode, giving high I_MB and low I_Fc. With ZEN, it binds the target, pulling it away. Adding Fc-COOH fills the β-CD cavities, increasing I_Fc and decreasing I_MB, thus raising the I_Fc/I_MB ratio proportionally to ZEN concentration. The sensor exhibits a wide linear range from 1 pg mL⁻¹ to 1000 ng mL⁻¹, with a detection limit of 0.4344 pg mL⁻¹. Furthermore, the method was successfully applied to the determination of ZEN in wine samples, yielding recovery rates between 94.00% and 104.60%, demonstrating excellent accuracy and applicability. These results indicate that the MCH/AuNPs/SH-Apt-MB/CG/GCE platform is a highly sensitive and selective electrochemical sensor for ZEN detection.