A novel Nb₂C MXene based aptasensor for rapid and sensitive multi-mode detection of AFB₁

Rapid and accurate on-site detection of aflatoxin B₁ (AFB₁) is of great significance for ensuring food safety. This work developed a dual mode aptasensor and a dual channel artificial neural network (ANN) intelligent sensor detection platform for simple and convenient quantitative detection of AFB₁ in food. This sensor was prepared by encoding manganese ion (Mn²⁺) mediated surface concave niobium carbide MXene nanomaterials (Nb₂C-MNs) using fluorescent group labeled aptamers (ssDNA-FAM). Mn²⁺-mediated Nb₂C-MNs exhibited better peroxidase-like and fluorescence quenching properties. Moreover, ssDNA-FAM as a fluorescent probe for the sensor also significantly enhanced the enzyme activity of Nb₂C-MNs. When AFB₁ existed, ssDNA-FAM preferentially bonded to AFB₁, resulting in fluorescence signal recovery and colorimetric signal weakening. Consequently, the multimodal biosensor could achieve fluorescence/colorimetric detection without the need for material and reagent replacement. In on-site detection, both ratio fluorescence and colorimetric signals could be collected using smartphones and analyzed and modeled on the developed ANN platform, achieving visual intelligent sensing. This multimodal biosensor had a detection line as low as 0.0950 ng/mL under optimal conditions, and also had the advantages of simple operation, fast and sensitive, and high specificity, which can meet the real-time on-site detection needs of AFB₁ in remote areas.