Safe and Effective Removal of Urea by Urease-Immobilized, Carboxyl-Functionalized PES Beads with Good Reusability and Storage Stability

Urea is one of the uremic toxins threating people's health. Herein, we prepared a kind of urease-immobilized beads to remove urea, which exhibited good hemocompatibility and high removal efficiency. Urease was covalently grafted onto carboxyl-group-functionalized polyether-sulfone beads, which were previously prepared by in situ cross-linking polymerization and phase inversion methods. The urease-immobilized beads had sufficient blood compatibility with low protein adsorption amount, undiminished clotting times, low hemolysis ratio, and suppressed complement activation and contact activation. Furthermore, the urease-immobilized beads showed good urea removal ability with a urea removal amount of 75.1 mg/g after incubating in 80 mg/dL urea solution for 480 min. In addition, the prepared urease-immobilized beads could maintain urea removal activity after being used for five cycles and showed satisfied activity even when stored for 15 days in phosphate buffer saline solution. Thus, the urease-immobilized beads may meet the potential application demand for safe and effective blood detoxification.