Selective Binding of Autoantibodies using Polymeric Gel for Management of Autoimmune Arthritis

Abstract The present study introduces a novel poly( N ‐isopropylacrylamide)‐collagen type II (PNiPAAm+CII) monolithic sub‐freezing gel column, designed to specifically capture CII‐specific autoantibodies directly from whole blood in a collagen‐induced arthritis (CIA) mouse model. Synthesized using a sub‐freezing gelation, the PNiPAAm+CII gel displayed a highly interconnected porous structure with micron‐sized pores (81–237 µm), allowing the smooth serum flow and cells passage. Mechanical testing showed good structural integrity, with a significantly higher elastic Young's modulus (Y = 2291.3 psi) than the control PNiPAAm gel (Y = 385.1 psi). Biocompatibility confirmed through the MTT assay, demonstrating good cytocompatibility. Hemocompatibility test showed negligible hemolysis for the PNiPAAm+CII gel (0.02%), significantly lower than the control PNiPAAm gel (84%). Additionally, the PNiPAAm+CII gel retained low binding of blood cells after incubation with whole blood. Anti‐inflammatory analysis showed no significant production of reactive oxygen species, upon cell contact. Notably, the PNiPAAm+CII gel demonstrated a strong biological affinity for CII‐specific autoantibodies, capturing 15.4 U mL −1 from CIA mouse serum. Remarkably, it selectively captured 24.5 U mL −1 of CII‐specific autoantibodies from whole blood without the need for pre‐processing. The PNiPAAm+CII gel offers a promising approach for the selective depletion of antigen‐specific IgG, potentially future management of autoimmune arthritis.