A methylene blue and Ag+ ratiometric electrochemical aptasensor based on Au@Pt/Fe-N-C signal amplification strategy for zearalenone detection

Abstract

Zearalenone (ZEN) contamination has attracted global attention of the food industry because of its toxicity to human body, so sensitive and rapid ZEN assays are critically important. Herein, methylene blue (MB) and Ag+ were used as dual-signal probes to design a ratiometric electrochemical aptasensor for facilely and accurately detection of ZEN, and an Au@Pt/Fe-N-C nanocomposites-induced signal amplification strategy was introduced to improve the sensitivity of the aptasensor. The Au@Pt/Fe-N-C nanocomposites had larger surface area and higher conductivity than single component materials. Firstly, DNA1 was modified on the gold electrode (AuE), so the signal probe Ag+ can produce a strong IAg+ by forming C-Ag+-C structure with DNA1. Simultaneously, the system MB-Au@Pt/Fe-N-C-dsDNA (containing aptamer and DNA2) cannot modify to AuE to obtain IMB. The aptasensor was incubated with ZEN that can compete with aptamer, and the released MB-Au@Pt/Fe-N-C-DNA2 can be modified on AuE by hybridization between DNA1 and DNA2, so as to generate a strong IMB. Au@Pt or Fe-N-C. The intensity of IAg+ decreased because it cannot combine with DNA1. The signal ratio IMB/IAg+ exhibited a good linear relationship with lgCZEN in the concentration of ZEN in the ranging of 1 × 10−5-10 ng/mL, and the limit of detection (LOD) and limit of quantitation (LOQ) were calculated as 5 fg/mL and 16.7 fg/mL, respectively. The successfully determination of ZEN in corn flour samples demonstrated that the ratiometric electrochemical aptasensor had excellent veracity, reliability and potential application prospects.