Co-immobilization of laccase and zinc oxide nanoparticles onto bacterial cellulose to achieve synergistic effect of photo and enzymatic catalysis for biodegradation of favipiravir

Abstract

The environmental persistence of pharmaceuticals represents a significant threat to aquatic ecosystems and human health, while limitations in conventional wastewater treatment methods underscore the urgent need for innovative and eco-friendly degradation strategies. Photobiocatalytic approaches provide a promising solution for the effective degradation of pharmaceutical contaminants by harnessing the synergistic effects of both photocatalysts and biocatalysts. In this study, we developed a photobiocatalytic composite by co-immobilizing laccase enzyme and zinc oxide nanoparticles on bacterial cellulose synthesized from orange peel waste. The optimal conditions for achieving maximum yield and efficiency of immobilization were investigated and the successful preparation of the composite was confirmed using infrared spectroscopy, X-ray diffraction, and scanning electron microscopy. The immobilized laccase showed K_m and V_max values of 0.68 ± 0.23 mM and 5.4 ± 0.86 μmol/min/L, respectively. The prepared composite was efficiently applied for degradation of favipiravir under optimum conditions including pH, temperature, and incubation time values of 4.0, 50 °C, and 90 min, respectively. The presence of ZnO nanoparticles in the structure of the photobiocatalyst significantly decreased the time of removal in comparison with both free and immobilized laccases. Although 80 ± 5.5 % of the enzyme activity was kept after 10 runs, the prepared photobiocatalyst retained 50 ± 4.6 % of its initial activity after 10 independent cycles. The study showed that the synergistic effects of laccase and ZnO nanoparticles possess the potentials to enhance degradation efficiency through combined light-driven and enzymatic approaches.

Keywords: Bacterial cellulose; Biodegradation; Enzyme immobilization; Favipiravir; Laccase; ZnO nanoparticles.