A nanofiber-based biocatalytic system: catalase immobilization on an electrospun PVP/GA carrier platform for hydrogen...

Hydrogen peroxide (H₂O₂) is widely used in industrial and environmental processes; however, excessive accumulation of H₂O₂ may cause oxidative damage and environmental hazards. Catalase (CAT) is an efficient enzyme capable of decomposing H₂O₂ into water and oxygen, but its practical application is limited by low stability and lack of reusability in its free form. In this study, CAT was immobilized onto electrospun polyvinylpyrrolidone/gum arabic (PVP/GA) nanofibers via glutaraldehyde-mediated covalent cross-linking to develop a stable and reusable biocatalytic system. The effects of key immobilization parameters, including CAT concentration, nanofiber amount, cross-linking time, and glutaraldehyde concentration, were systematically optimized, and a maximum immobilization efficiency of 81.2% was achieved under optimal conditions. The immobilized enzyme exhibited improved thermal stability, broader pH tolerance, enhanced pH stability, and superior storage stability compared to the free enzyme. Kinetic analysis revealed an increase in both K _m and V _max values after immobilization, indicating enhanced catalytic capacity despite partial diffusion limitations. Application experiments demonstrated that the immobilized CAT achieved complete degradation of H₂O₂ at concentrations up to 100 mM within 25 min, while maintaining significant catalytic performance during repeated operational cycles. Moreover, the immobilized enzyme retained 52% of its initial activity after 30 days of storage, highlighting its improved stability. These findings demonstrate that PVP/GA nanofiber supported CAT represents a promising and reusable biocatalytic system for efficient H₂O₂ detoxification in environmental and industrial applications.