Laccase-encapsulated metal-organic frameworks (Lac@MOF): Removal of BPA, a major endocrine disruptor, from the aquatic environment

Bisphenol A (BPA) is an endocrine disruptor. The utilization of enzymes in the bioremediation of these compounds offers advantages such as high catalytic efficiency, non-toxicity, high substrate specificity, and short reaction times. However, the use of enzymes in their soluble forms limits their practical applications and presents certain disadvantages, including sensitivity to denaturing agents, non-reusability, and low stability. To address these limitations, enzyme immobilization is a significant method. Recently, porous and large-surface-area metal-organic frameworks (MOFs) have been considered potential candidates for enzyme immobilization. In this study, BPA removal was achieved using an enzymatic process. Encapsulation of laccase was accomplished for the first time during the synthesis of Co ²⁺ -and malonic acid-based MOF structures. Optimization and structural characterization (SEM and TGA) of laccase-encapsulated MOF structures (Lac@MOF) were conducted. The enzymatic properties, including temperature, pH, reusability, and kinetic properties of Lac@MOF structures synthesized under optimal conditions, were investigated. The catalytic performance of the laccases increased subsequent to immobilization. The temperature profile at which it exhibited activity broadened and demonstrated enhanced activity in the alkaline range. Notably, the thermal stability results indicated that the activity of the Lac@MOF structures increased by 147% at 60°C, 157% at 70°C, and 134% at 80°C compared to the free enzyme. After the 7th use, 60% of immobilized laccase activity was retained. For BPA, 66% removal was achieved after 230 min.