A direct competitive nanozyme-linked immunosorbent assay based on MnO2 nanosheets as a catalytic label for the determination of fumonisin B1

Abstract

A direct competitive nanozyme-linked immunosorbent assay (dcNLISA) based on MnO₂ nanosheets (MnO₂ NSs) as a nanozyme label was developed for the highly sensitive determination of fumonisin B₁ (FB₁). MnO₂ NS-labeled fumonisin B₁-bovine serum albumin was easily synthesized as a competing antigen for the dcNLISA. And color changes derived from the MnO₂–3,3′,5,5′-tetramethylbenzidine (TMB) system were exploited as the output signals of the dcNLISA. Several experimental parameters including the concentrations of the coating antibody, pH values, ionic strength and methanol concentration were optimized. Under the optimal conditions, the proposed method demonstrated a linear range (1.17–20.74 ng mL⁻¹) with a reliable correlation coefficient (R² = 0.9989), a satisfactory limit of detection (0.63 ng mL⁻¹) and high selectivity for the detection of FB₁. The recoveries of FB₁ in spiked corn and wheat samples were in the range of 85.31–108.16% with coefficients of variation (CVs) ranging from 6.14% to 9.23%. Meanwhile, the testing results showed good consistency (R² = 0.9892) between the developed dcNLISA and the reference method, liquid chromatography/mass spectrometry/mass spectrometry (LC-MS/MS) method. The proposed method was proven to be simple, sensitive, cost-effective and reliable for the screening of FB₁ in cereals.