Phenylglyoxaldehyde-Functionalized Polymeric Sorbents for Urea Removal from Aqueous Solutions

Improving the adsorption performance of urea by using polyhydroxy groups to modify two-dimensional Ti3C2Tx

Wearable artificial kidney can provide continuous dynamic dialysis for uremia patients. For the sake of practical application, the critical step is to find an adsorbent that can effectively remove urea and have excellent biological compatibility. The layered Ti3C2Tx (DL-Ti3C2Tx) with high specific surface area and good dispersion was prepared by a two-step etching method. From the first principles calculation, urea can be adsorbed by different groups (-F, -O, -OH) on the surface of Ti3C2Tx, among which -OH has the greatest binding energy to urea. Therefore, DL-Ti3C2Tx was modified with different alkali solutions (KOH, NaOH, LiOH) to introduce -OH on the surface, which can increase the adsorption capacity of urea. The experimental results showed that DL-Ti3C2Tx (LiOH-Ti3C2Tx) after treated by LiOH had the highest urea adsorption efficiency, and the urea removal rate of LiOH-Ti3C2Tx was still higher than 92% when the urea concentration was 500 mg/L. In the Simulated dialysate, Ti3C2Tx treated with three kinds of alkali solutions still maintained a good adsorption efficiency for urea, and still had a certain adsorption capacity after recycling for four times. Biocompatibility experiments showed that Ti3C2Tx in different concentrations did not cause hemolysis of erythrocyte, and had no obvious damage to vascular endothelial cells. This study greatly improves the urea adsorption efficiency of MXene, which has a broad application prospect in the selection of adsorbent for wearable artificial kidney.

Portable, wearable and implantable artificial kidney systems: needs, opportunities and challenges

Haemodialysis is life sustaining but expensive, provides limited removal of uraemic solutes, is associated with poor patient quality of life and has a large carbon footprint. Innovative dialysis technologies such as portable, wearable and implantable artificial kidney systems are being developed with the aim of addressing these issues and improving patient care. An important challenge for these technologies is the need for continuous regeneration of a small volume of dialysate. Dialysate recycling systems based on sorbents have great potential for such regeneration. Novel dialysis membranes composed of polymeric or inorganic materials are being developed to improve the removal of a broad range of uraemic toxins, with low levels of membrane fouling compared with currently available synthetic membranes. To achieve more complete therapy and provide important biological functions, these novel membranes could be combined with bioartificial kidneys, which consist of artificial membranes combined with kidney cells. Implementation of these systems will require robust cell sourcing; cell culture facilities annexed to dialysis centres; large-scale, low-cost production; and quality control measures. These challenges are not trivial, and global initiatives involving all relevant stakeholders, including academics, industrialists, medical professionals and patients with kidney disease, are required to achieve important technological breakthroughs.