Synthesis and Adsorption Isotherm Study of Molecularly Imprinted Polymer Based on Fe3o4-Au Nanoparticles for Determination of Aflatoxin B1 in Food Sample

Introduction: Mycotoxins are a major class of natural contaminants that humans are typically exposed to throughout their life. This chemically diverse group of toxic secondary metabolites are produced by filamentous fungi and frequently occur in our diet. Aflatoxin B1 is one of the most toxic and dangerous mycotoxins, posing serious health risks. Aflatoxin B1 is like parasitic on foodstuff and breed under the suitable conditions, which can reduce the quality of agricultural products, resulting in the huge economic loss. Therefore, its identification in foodstuffs is critical. High Performance Liquid Chromatography, Liquid Chromatography-Mass Spectrometry, fluorescence and colorimetry are conventional methods for quantification of mycotoxins. However, Chromatography and immunoaffinity methods are sensitive and selective but they have disadvantages such as high cost, time consuming procedures and low stability of antibodies. Therefore, this study aims to synthesize an efficient and low-cost sorbent for selective adsorption of Aflatoxin B1 in food.
 
Materials and Methods: In this research, a molecularly imprinted polymer (MIP) based on Fe₃O₄-Au nanocomposite was synthesized and used for the detection of Aflatoxin B1 in food sample. The synthesis of the polymer was carried out using the non-covalent imprinting method. Aflatoxin B1 standard sample, methacrylic acid, ethylene glycol dimethacrylate (EGDMA), azobisisobutyronitrile (AIBN) were added to porogenic solvents as the template molecule, functional monomer, cross-linker and initiator, respectively. The mixture was stirred at 60°C under the nitrogen atmosphere. The powder was subjected to washing with the mixture of solvent (methanol - acetic acid) to remove template molecule. Characterization of the synthesized Magnetic molecularly imprinted polymer (MMIP) was assessed by scanning electron microscopy (SEM), Fourier-transform infrared spectroscopy (FTIR), transmission electron microscopy (TEM), and magnetic properties was evaluated by vibrating sample magnetometry (VSM).
 
Results and Discussion: The morphology images of the synthesized MMIP confirmed the formation of perfectly structured magnetic sorbent for Aflatoxin B1 adsorption. The limit of detection (LOD) and limit of quantification (LOQ) were estimated to be 6.120×10^-3 and 1.860×10^-2 mg/L, respectively. Adsorption capacity of Aflatoxin B1 on MMIP and MNIP were obtained 8.975 mg/g and 4.200 mg/g, respectively. The magnetic molecularly imprinted polymer showed a higher affinity for Aflatoxin B1 compared to the non-imprinted magnetic polymer, confirming the successful imprinting process, according to the results. The evaluation of Langmuir and Freundlich isotherm models indicated that the Langmuir isotherm with a coefficient of determination (r²) value of 0.999 was as the best fitting model to describe the adsorption process. The proposed method showed satisfactory recovery in range of 94.062%-97.213% for determination of Aflatoxin B1 in food sample. Also, relative standard deviation was calculated lower than 3.721%.
 
Conclusions: Fe₃O₄-Au@MIP could be used as an effective adsorbent for the separation and detection of Aflatoxin B1 in food samples. The use of UV-Vis spectrophotometer for quantification of Aflatoxin provides a quick, cost-effective and simple technique which could be a proper alternative to time consuming, high cost and complicated methods. The high binding capacity and ease of use make it a suitable candidate for routine analysis of food safety. Disuse of organic solvents on a large scale is another advantage that cannot be ignored in this project which makes this method environmentally friendly and practical.