Coordination of thin-film nanofibrous composite dialysis membrane and reduced graphene oxide aerogel adsorbents for elimination of indoxyl sulfate

The protein-bound uremic toxins, represented by indoxyl sulfate (IS), have been associated with the progression of chronic kidney disease and the development of cardiovascular disease in the presence of impaired renal function. Herein, we proposed a novel strategy of thin-film nanofibrous composite (TNFC) dialysis membrane combined with reduced graphene oxide (rGO) aerogel adsorbents for clinical removal of IS as well as high retention of proteins. The TFNC membrane was prepared by electrospinning in conjunction with coating-reaction method and proved to have good selectivity and permeability. To further improve the removal rate of toxins, we used a medium hydrothermal method following by freeze-drying treatment to obtain the rGO aerogel adsorbents. It exhibited excellent adsorption for IS with a maximum adsorption capacity of 69.40 mg∙g−1 through π−π interaction and hydrogen bonding interaction based on Langmuir isotherm models. Time-dependent absorption experiments showed that it reached adsorption equilibrium within 4 h, which was matched with the hemodialysis time. The coordination was significantly exhibited by introducing rGO aerogel blocks into the dialysate for absorbing the diffused free IS during hemodialysis. Taking the advantages of the TFNC dialysis membrane and the rGO aerogel, the volume of dialysate for hemodialysis was only one-tenth of that without adsorbent blocks but with very comparable dialysis performance (the clearance of IS at 51.8% and the retention of HSA over 98%), which could lighten conventional hemodialysis effectively and be benefit to realize the miniaturization of the hemodialysis equipment. Therefore, the coordination of the TFNC dialysis membrane and rGO aerogel adsorbents would open a new path for the development of portable artificial kidney.