Laccase immobilized on magnetic nanoparticles for the degradation of imidacloprid: Based on multi-spectroscopy and molecular docking

As a typical class of environmental endocrine disruptors, imidacloprid (IMI) poses a potential threat to the sustainable survival and reproduction of living beings and human beings. Consequently, it is crucial to establish an efficient degradation method to remove imidacloprid from the environment. The present study aimed to investigate the immobilized laccase for the detoxification of imidacloprid via multi-spectroscopy and molecular docking. Herein, laccase was immobilized on magnetic nanoparticles (NiFe₂O₄ NPs) using a novel immobilization technique based on glutaraldehyde cross-linking polymerization. A single factor experiment approach was used to optimize the immobilization conditions, which included temperature, pH, enzyme concentration, and reaction time. Notably, the optimal condition was determined as 50℃, pH 4, laccase concentration of 1.0 mg/mL and 1.5 h. Based on the immobilization conditions, the degradation efficiency of immobilized laccase was 41.92 % after 24 h. Following eight degradations, the immobilized laccase's relative activity stayed at 34.09 % of its initial activity, demonstrating exceptional operational stability and reusability. Moreover, the binding free energy between imidacloprid and laccase was calculated on the basis of molecular docking, as -7.2 kcal/mol. This study provides experimental techniques and theoretical references for the biological digestion of hazardous pesticide residues in the environment. In addition, this study improved the shortcomings of free laccase, provided an environmentally friendly and efficient method for the degradation of imidacloprid.