Approaching Immobilization of Enzymes onto Open Porous Basotect®

For the first time, commercial macroporous melamine formaldehyde foam Basotect® (BT) was used as a basic carrier material for both adsorptive and covalent enzyme immobilization. In order to access inherent amino groups, the Basotect® surface was pretreated with hydrochloric acid. The resulting material revealed 6 nmol of superficial amino groups per milligram Basotect®. Different optimized strategies for tethering the laccase from Trametes versicolor and the lipase from Thermomyces lanuginosus onto the pre-treated Basotect® surface were studied. Particularly, for covalent immobilization, two different strategies were pursued: lipase was tethered via a cross-linking method using 1-ethyl-3-(3-dimethylaminopropyl)carbodiimide, and laccase was bound after functionalizing Basotect® with hydrophilic copolymer poly(ethylene-alt-maleic anhydride) (PEMA). Prior to laccase immobilization, the PEMA coating of Basotect® was verified by ATR-FTIR analysis. Subsequent quantification of available high-reactive PEMA anhydride moieties revealed an amount of 1028 ± 73 nmol per mg Basotect®. The surface-bound enzyme amounts were quantified as 4.1–5.8 μg per mg Basotect®. A theoretical surface-covered enzyme mass for the ideal case that an enzyme monolayer was immobilized onto the Basotect® surface was calculated and compared to the amount of adsorptive and covalently bound enzymes before and after treatment with SDS. Furthermore, the enzyme activities were determined for the different immobilization approaches, and the stability during storage over time and against sodium dodecyl sulfate treatment was monitored. Additionally, PEMA-BT-bound laccase was tested for the elimination of anthropogenic micropollutant bisphenol A from contaminated water in a cost-effective and environmentally-friendly way and resulted in a degradation rate higher than 80%