Kidney failure leads to the accumulation of metabolites in the blood compartment. This build-up of metabolites has been associated with increased mortality and morbidity in these patients; thus, these metabolites are commonly called uremic toxins. The retention of some uremic toxins in the blood results from a strong interaction with serum albumin, preventing their clearance using standard hemodialysis techniques. Adsorbents are considered the next-generation technology for clearing uremic toxins from the blood, and iron oxide magnetic nanoparticles are a promising material due to a high surface area that is easily modified and the ability to remove them from blood with an external magnetic field. Plasma protein adsorption and clot formation kinetics were determined for unmodified and albumin-modified iron oxide magnetic nanoparticles. Albumin was selected because it can bind uremic toxins, and it is commonly used to passivate surfaces. Coatings were formed and characterized using transmission electron microscopy, thermogravimetric analysis, and zeta-potential analysis. Clotting kinetics, total protein assays, and immunoblots were used to analyze the effect surface modification has on protein adsorption events. Unmodified nanoparticles showed rapid clotting and more adsorbed protein compared to albumin-coated iron oxide nanoparticles. Immunoblots show that modified particles showed changes in albumin, protein C, Immunoglobulin G, transferrin, fibrinogen, α1-antitrypsin, vitronectin, plasminogen, prothrombin, and antithrombin levels compared to unmodified controls. The hemocompatibility of adsorbent materials is essential to their clinical application in clearing the blood of uremic toxins.

Kidney disease causes the retention of uremic metabolites in blood, which is associated with many comorbidities. Hemodialysis does not properly clear many metabolites, including large, middle-sized, and small protein-bound uremic toxins (PBUTs). Adsorption strategies for metabolite removal require the development of engineered adsorbents with tailored surfaces to increase the binding of desired metabolites. Albumin is uniquely positioned for modifying blood-contacting surfaces to absorb uremic metabolites, as it (i) minimizes non-specific protein adsorption and (ii) binds a range of molecules at Sudlow Sites I and II with different affinities. It is unknown if albumin-modified surfaces retain the adsorption qualities of solution-free albumin, namely, adsorption stability or specificity. Herein, albumin was covalently attached to iron oxide nanoparticles and characterized using multiple methods. Metabolite adsorption was conducted by incubating particles in a model solution of thirty-three uremic metabolites associated with kidney failure. Adsorption efficiency, selectivity, and stability were affected by albumin concentration and incubation time. Metabolite adsorption was found to change with time, and it was more effective on albumin-modified particles than unmodified controls. The findings outlined in this paper are crucial for the design of next-generation advanced blood-contacting materials to enhance dialysis and blood purification for patients with kidney disease.