Molecularly imprinted Fe3O4 nanoparticles-based magnetic 3D photonic crystal microspheres for specific adsorption of aflatoxin B1 in grains

Aflatoxin B₁ (AFB₁) is the major toxic mycotoxin that contaminates grains at trace levels, necessitating the development of an efficient and simple extraction method to enrich it in samples. Here, magnetic molecularly imprinted Fe₃O₄ nanoparticles (MMIPs) were first synthesized by employing 5,7-dimethoxy coumarin as the template and methacrylic acid combined with styrene as the functional monomers. These MMIPs exhibited excellent selective recognition capabilities for AFB₁, based on which, a novel molecularly imprinted magnetic inverse opal photonic crystal microsphere (MIP@MIPCM) was fabricated via a droplet-based microfluidic self-assembly technique. The MIP@MIPCMs enabled specific recognition of AFB₁ and were used as an extraction material, achieving a binding capacity of 842.7 ng/mg within 20 min. Coupled with high-performance liquid chromatography (HPLC), a sensitive and accurate analytical method was established for AFB₁ detection with a detection limit of 0.35 μg/kg and recovery rates of 90-109 % in real samples.