Cross-validated dual-mode aptasensor enabled by rolling circle amplification-generated G-quadruplex and Au@Ti3C2Tx MXene@MoSe2 for reliable zearalenone detection

A dual-mode (colorimetric/electrochemical) aptasensor was developed for ZEN detection. • Au@Ti 3 C 2 T x MXene@MoSe 2 was synthesized to enhance electrode conductivity and surface area. • RCA was integrated to generate G-quadruplexes for both electrochemical and colorimetric readouts. • Electrochemical mode achieved 1.23 fg/mL LOD; colorimetric mode enabled convenient visual screening. • The sensor exhibited excellent selectivity, stability, and recoveries (89.6–106.2%) in real samples. Zearalenone (ZEN), a nonsteroidal mycotoxin produced by Fusarium fungi, widely contaminates cereals and their derived products, posing a serious threat to human health. In this study, a highly sensitive dual-mode (colorimetric and electrochemical) aptasensor for ZEN was constructed. The sensor employs rolling circle amplification (RCA) to efficiently generate long single-stranded DNA rich in G-quadruplex sequences, combined with an electrode modified with an Au@Ti 3 C 2 T x MXene@MoSe 2 nanocomposite, thereby achieving synergistic signal amplification and dual readout. In the electrochemical mode, the RCA product is anchored through hybridization between the primer and the capture probe on the electrode surface, where it adsorbs abundant methylene blue to produce a square wave voltammetry (SWV) response. In the colorimetric mode, the G-quadruplex structures self-assemble with hemin to form peroxidase-mimicking DNAzymes, which catalyze the TMB chromogenic reaction to generate a visual signal. Experimental results showed that the electrochemical mode achieved a detection limit as low as 1.23 fg/mL (detection range: 10 −3 -10 4 pg/mL), while the colorimetric mode exhibited a detection limit of 64.89 fg/mL (detection range: 1 pM-10 μM). The aptasensor demonstrated excellent selectivity, good stability, and satisfactory reproducibility for ZEN, with spiked recoveries ranging from 89.6% to 106.2% in real corn flour and beer samples. This dual-mode sensing platform effectively eliminates single-mode interferences through signal cross-validation, providing a reliable technical means for the accurate and rapid detection of trace ZEN in food safety. Download: Download high-res image (117KB) Download: Download full-size image