A review: current urea sorbents for the development of a wearable artificial kidney

The wearable artificial kidney (WAK) holds great promise as a potential alternative to hemodialysis for treating end-stage renal disease (ESRD), offering patients longer and more frequent dialysis within a compact device. However, a critical challenge in developing a practical WAK lies in ensuring sufficient removal of urea, a key waste product in ESRD. Current developed urea removal technologies include enzymatic hydrolysis by urease, electro-oxidation, and sorbent systems. Among them, utilizing adsorption-based strategies for urea removal represents a promising approach in WAK design. This article reviews a variety of sorbent materials over last five years, encompassing both inorganic-based sorbents and organic-based sorbents. The inorganic-based sorbents include activated carbon, silica, zeolite, MXene, graphene/graphene oxide, and fullerene, while the organic-based sorbents contain chitosan, molecularly imprinted polymers, starch, celluloses, and metal organic frameworks. Furthermore, insightful perspectives on future research directions and development of urea sorbents for WAK are discussed.