Laccase-immobilized tannic acid-mediated surface modification of halloysite nanotubes for efficient bisphenol-A degradation

Abstract

the Michael addition and/or Schiff base condensation between quinone groups on poly(tannic acid) layer surfaces and exposed amine groups on laccase surfaces. Under the optimum conditions, this newly fabricated support retained good enzyme-loading and activity recovery properties with 197.9 mg protein per gram of support and 55.4% of activity recovery being achieved. In addition, this immobilized laccase was less influenced by pH, temperature, and inhibitor changes and exhibited higher storage stability than free laccases as more than 70% of initial activity was retained by the immobilized laccase, while less than 30% was retained for free laccase after one-month storage at 4 °C. Finally, a higher bisphenol-A (BPA) removal efficiency and more reuse cycles were demonstrated for immobilized laccases. As a result, this TA-mediated surface modification is a simple and green method for biological macromolecule immobilization on HNTs in one step.