Collagen-modified chitosan microsphere as a novel hemoperfusion adsorbent for efficient removal of bilirubin from human plasma

Hemoperfusion is one of the most effective treatments for the removal of bilirubin from the blood. Chitosan (CS) has been widely investigated as a hemoperfusion adsorbent to remove bilirubin due to its biocompatibility and biodegradability. However, the limited adsorption capacity of CS for free bilirubin or albumin-rich bilirubin solution, and the strong adsorption for albumin, limit its extensive use. The goal of this work is to improve specific bilirubin adsorption of CS while reducing its adsorption for albumin. In this study, collagen (Col) was chosen as a ligand and grafted onto the surface of CS microspheres to form CS-Col microspheres and therefore to improve their adsorption performance for bilirubin. The maximum adsorption capacity of the CS-Col microspheres for bilirubin increases from 24.2 to 76.9 mg/g. The enhancement factor is higher than that of other CS-based adsorbents. Moreover, the adsorption of CS-Col microspheres for albumin is effectively reduced to 2.6 %, while maintaining good blood compatibility. Compared to other CS-based bilirubin adsorbents, our CS-Col microspheres have the advantage of specific adsorbing bilirubin against albumin due to introducing collagen. This work provides new directions for designing high-performance bilirubin adsorbents. Our CS-Col microspheres show great promise for the treatment of hyperbilirubinemia.