Production of a robust nanobiocatalyst for municipal wastewater treatment

Immobilization is a fundamental method to improve both enzyme activity and stability. In the present work, the process previously described for immobilizing laccase - an enzyme oxidizing phenolic compounds - onto fumed silica was optimized, in order to efficiently produce industrially relevant amounts of a nanobiocatalyst for biological micropollutant elimination, whilst saving 80% of surface modification agent (3-aminopropyl triethoxy silane) and 90% of cross-linker (glutaraldehyde). Minimized losses during preparation and favorable effects of immobilization yielded conjugates with drastically increased enzymatic activity (164% of invested activity). Long-term stability and activity regarding bisphenol A (2,2-bis(4-hydroxyphenyl)propane) removal of the synthesized biocatalyst were assessed under application-relevant conditions. With 81.1±0.4% residual activity after 7 days, stability of conjugates was drastically higher than of free laccase, which showed virtually no activity after 1.5 days. These results illustrate the huge potential of fumed silica nanoparticles/laccase-composites for innovative biological wastewater treatment.