Özgün Vatansever, Ceyhun Işık, Mustafa Teke
Abstract In this research, laccase was immobilized on electrospun nanofibrous matrix composed of poly(vinyl alcohol) and xanthan gum (PVA/XG) using a two-step process involving physical adsorption and subsequent cross-linking with glutaraldehyde. Several key immobilization parameters, including enzyme concentration, nanofiber content, adsorption duration, and cross-linker concentration, were systematically optimized to enhance catalytic performance. Under optimal conditions, the immobilized laccase displayed a specific activity of 59.47 ± 1.29 U/g and an immobilization efficiency of 49.44 ± 1.57. tructural and morphological analyses (FTIR, DSC, TGA, and SEM) confirmed the successful incorporation of the enzyme into the nanofibrous matrix. Morphological evaluation revealed reduced porosity, increased fiber diameter, and expanded surface area following immobilization. Compared to the free enzyme, the immobilized laccase exhibited a shift in optimum pH from 4.5 to 5.5 and a broadened optimum temperature range from 35 °C to 35–45 °C. Kinetic analysis revealed moderate increases in K m and slight decreases in V max , indicating partial diffusion limitations while maintaining catalytic function. Furthermore, the immobilized enzyme retained more than 50% of its initial activity after 20 reuse cycles and demonstrated stable storage performance at both 4 °C and 25 °C. The system effectively degraded phenol and related compounds (up to 100 mg/L), with phenol showing the highest degradation rate. These findings highlight the potential of the PVA/XG nanofibrous platform as a robust medium for enzyme immobilization in environmental bioremediation applications.