Urease immobilized electrospun PVA/chitosan nanofibers with improved stability and reusability characteristics: an application for removal of urea from artificial blood serum.

Electrospun polyvinyl alcohol (PVA)/Chitosan nanofibers were successfully prepared and were used as carriers for the first time in urease immobilization. Also, urease immobilized electrospun PVA/Chitosan nanofibers were applied for the removal of urea from artificial blood serum by recycled reactor. The nanofibers were optimized and synthesized by electrospinning technique according to the operational parameters. The morphology and structure of the nanofibers were characterized by scanning electron microscopy (SEM), attenuated total reflection-Fourier transform infrared spectroscopy (ATR-FTIR) and thermogravimetric analysis (TGA). Urease was immobilized on the nanofibers by adsorption and crosslinking methods. According to immobilization results, nanofiber enhanced urease stability properties like thermal stability, pH stability, and reusability. Urease immobilized electrospun PVA/Chitosan nanofiber protected its activity by 85% after 10 uses and 45% after 20 uses. Urea removal rates of artificial blood serum were as follows: 100% at 1st cycle, 95% at 2nd, 3rd and 4th cycles; 85% at the 5th cycle; 76% at the 6th cycle, and 65% at the last three cycles.