Ionic liquid enhanced fabrication of small-size BSA-Cu laccase mimicking nanozymes for efficient degradation of phenolic compounds

Laccase is a very promising natural enzyme in the application of biochemical industry, but its application is severely limited by its high cost and poor stability. To overcome the inherent defects of natural laccase, here, we prepared a new type of small-size mimicking nanozymes based on self-assembly of bovine serum albumin (BSA) and copper sulfate (CuSO₄) with help of ionic liquid (IL). The effects of different ILs on the catalytic activity of the product (BSA-Cu nanozymes) were investigated, and it was found that BSA-Cu nanozymes with stable structures could be obtained in tetrabutylammonium hydroxide (TBAOH). Compared with laccase, the V_max/K_m of BSA-Cu nanozymes prepared by TBAOH was higher (0.081) than that of laccase (0.029), and the stability of BSA-Cu nanozymes were significantly enhanced in terms of pH, temperature, and ionic strength. The BSA-Cu nanozymes were utilized for detection and degradation of a series of phenolic substances, among which catechol was the most effective. In the detection of epinephrine, BSA-Cu nanozymes achieved a lower detection limit (0.38 µg/mL) and were more sensitive than laccase (3.53 µg/mL). The application of ILs can improve the mimicking laccase nanozymes performance and has great potential for further industrial application.