Nanoporous biomaterials for uremic toxin adsorption in artificial kidney systems: A review

Abstract

Hemodialysis, one of the earliest artificial kidney systems, removes uremic toxins via diffusion through a semipermeable porous membrane into the dialysate fluid. Miniaturization of the present hemodialysis system into a portable and wearable device to maintain continuous removal of uremic toxins would require that the amount of dialysate used within a closed-system is greatly reduced. Diffused uremic toxins within a closed-system dialysate need to be removed to maintain the optimum concentration gradient for continuous uremic toxin removal by the dialyzer. In this dialysate regenerative system, adsorption of uremic toxins by nanoporous biomaterials is essential. Throughout the years of artificial kidney development, activated carbon has been identified as a potential adsorbent for uremic toxins. Adsorption of uremic toxins necessitates nanoporous biomaterials, especially activated carbon. Nanoporous biomaterials are also utilized in hemoperfusion for uremic toxin removal. Further miniaturization of artificial kidney system and improvements on uremic toxin adsorption capacity would require high performance nanoporous biomaterials which possess not only higher surface area, controlled pore size, but also designed architecture or structure and surface functional groups. This article reviews on various nanoporous biomaterials used in current artificial kidney systems and several emerging nanoporous biomaterials. © 2016 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 105B: 1232-1240, 2017.

Producing hybrid nanofiber‐based on /PAN/Fe3O4/zeolite/nettle plant extract/urease and a deformed coaxial natural polymer to reduce toxicity materials in the blood of dialysis patients

“…Composite membrane with dimension of 2 cm × 2 cm was cut and arrayed at different times (4,8,12,16,20,24,28, 32, 36 min) with 5 M urea solution. About 3 mL, Nessler reagent was added to the urea solution.…”

“…5 Among the most common crystalline porous particles, zeolites are one of the best alumina silicates used for numerous molecular sieve and high resistance in chemical and thermal process. 16 Polyethersulfone (PES) and polyurethane (PU) were used for purifying urea and creatinine in renal mycrolic chip. 7 Another porous membrane, which has good stability and high resistance to bacteria and viruses, is Polyacrylonitrile, 7,8 which help to eliminate uremic toxins.…”

“…15 Activated carbon and zeolites were the first group of adsorbent in hem perfusion process. 16 Polyethersulfone (PES) and polyurethane (PU) were used for purifying urea and creatinine in renal mycrolic chip. 17 One method used for measuring ammonia in urea decomposition is the Nessler's reagent adsorption as shown in reactions 1 and 2 for urea decomposition by urease enzymes.…”

Optimized performance of the integrated hepatic cell‐loaded cryogel‐based bioreactor with intermittent perfusion of acute liver failure plasma

“…Plasma from patients with ALF is rich in hepatotoxic compounds such as necrotic cells, lipopolysaccharides, and compounds normally detoxified by the liver such as ammonia and bile acids, all of which may affect the functionality of the BAL device adversely. These cytotoxic effects of the plasma on the cells in the BAL device may be reduced by introducing an adsorbent such as activated carbon that adsorbs to some extent the water‐soluble toxins present in the plasma . Thus, we designed a hybrid bioreactor that integrates an activated carbon cloth (to adsorb most of the toxins that pose a threat to the viability of the cells seeded in the bioreactor) with the hepatic cell‐loaded cryogel bioreactor in one compact system to improve the efficacy of the bioreactor for use as a BAL …”

“…These cytotoxic effects of the plasma on the cells in the BAL device may be reduced by introducing an adsorbent such as activated carbon that adsorbs to some extent the water-soluble toxins present in the plasma. 15 Thus, we designed a hybrid bioreactor that integrates an activated carbon cloth (to adsorb most of the toxins that pose a threat to the viability of the cells seeded in the bioreactor) with the hepatic cell-loaded cryogel bioreactor in one compact system to improve the efficacy of the bioreactor for use as a BAL. 16 The efficacy of the activated carbon cloth in terms of absorption of toxins such as bilirubin and ammonia was evaluated in the earlier work and found to be between 10 and 20%.…”