Immobilization of horseradish peroxidase onto electrospun polyurethane nanofiber matrices

Abstract

In this work, horseradish peroxidase (HRP) was immobilized onto polyurethane nanofiber membranes. The following variables were optimized to maximize the surface density of grafted HRP (Q): NaClO functionalization time (tf), immobilization time (ti), HRP concentration of the immobilization solution (CHRP), and immobilization temperature (T). Catalytic activity was evaluated using the decolorization reaction of Orange II (OII). A statistical analysis of SEM images demonstrates that fiber diameters (d) of native (M), AGE-modified (MA), and HRP immobilized (MAH) electrospun membranes obeyed a log-normal distribution and that the effects of the NaClO activation procedure, and the use of MAH membranes in OII oxidation during 4 h on the fiber size were negligible. Although obtained membranes at 40°C (MAH9540) presented the highest Q, matrices obtained at 20°C (MAH9520) exhibited the highest catalytic activity, indicating that HRP was partially inactivated during the immobilization at 40°C. Reusability tests demonstrated that membranes retained between 11% and 33% of their initial enzyme activity after a total reaction time between 4 and 8 h.