Establishment of an Improved ELONA Method for Detecting Fumonisin B1 Based on Aptamers and Hemin-CDs Conjugates

Fumonisin B1 (FB1) is a strong mycotoxin that is ubiquitous in agricultural products. The establishment of rapid detection methods is an important means to prevent and control FB1 contamination. In this study, an improved enzyme-linked oligonucleotide assay (ELONA) method was designed and tested to detect the contents of FB1 in maize (corn) samples. F10 modified with biotin was bound to an enzyme label plate that was coated with streptavidin (SA) in advance, and carbon dots (CDs) were used to catalyze the color of tetramethylbenzidine (TMB). The complementary chain of F10 was modified with an amino group and coupled with CDs to obtain conjugates. The sample and conjugates were then added to the enzyme plate coated with F10 (an FB1 aptamer). Upon completion of the color reaction, the absorbance was measured at 450 nm. The LOD of this method was 4.30 ng/mL and the LOQ was 13.03 ng/mL. We observed a linear relationship in the FB1 concentration range of 0–100 ng/mL. The standard curve was y = −0.001482 × x + 0.3463, R2 = 0.9918, and the experimental results could be directly measured visually. The recovery of the maize sample was 97.5–99.23% and 94.54–99.25%, and the total detection time was 1 h.