Chitosan/κ-Carrageenan/Carbon Nitride HydrogelAdsorbent for Removing Free Hemoglobin from Extracorporeal Circulation

Extracorporeal circulation often causes mechanical damage to erythrocytes, which release hemoglobin into the plasma, resulting in postsurgical hazard, so lowering the free hemoglobin (f-Hb) level in the blood is important. In this study, based on the good biocompatibility of chitosan/κ-carrageenan and the adsorption effect of carbon nitride, a chitosan/κ-carrageenan/carbon nitride (CS/κ-Car/C₃N₄) hydrogel was prepared through the charge electrostatic interaction between polysaccharides. The incorporation of C₃N₄ enhanced both the adsorptive capacity and the stability of the hydrogel. Specifically, the CS/κ-Car/C₃N₄-0.4% hydrogel exhibited an adsorption amount of 185.79 mg/g for human hemoglobin, approximately twice that of the CS/κ-Car hydrogel. The CS/κ-Car/C₃N₄ hydrogel also showed a significantly lower breakage and degradation rate. In addition, the CS/κ-Car/C₃N₄ hydrogel did not induce hemolysis, complement activation, or coagulate when in contact with blood and showed good blood compatibility. Furthermore, in vivo studies in rabbits revealed that the CS/κ-Car/C₃N₄ hydrogel significantly reduced elevated f-Hb levels to near-normal concentrations postcirculation, without inducing any severe adverse effects on the subjects. This investigation has elucidated that the CS/κ-Car/C₃N₄ hydrogel possesses superior adsorptive efficacy and biocompatibility, effectively clearing f-Hb in vivo. Consequently, the findings of this study offer novel insights into the design paradigm for adsorbents intended for blood circulation applications.