Zwitterionic polymers as high-performance coatings for hemoperfusion adsorbents and their chemisorption of protein-bound toxins through computational simulations

It remains a challenge for commercial hemoperfusion adsorbents to efficiently remove multiple protein-bound toxins in the clinical treatment of liver and kidney failure. Here, polystyrene divinylbenzene microspheres (PS-DVB) were surface-modified by poly(carboxybetaine methacrylate) (poly-CBMA) through controlled polymerization, named PCBMA. PS-DVB served as a supporting backbone and provided enormous specific surface, while a layer of the poly-CBMA aimed at efficiently removing various toxins and attaining better biocompatibility. After modification, the mesoporous analysis revealed a high specific surface area of 527 m2/g. More notably, compared with PS-DVB, PCBMA showed an 830%, 130%, and 26% increase in the adsorption capacity of p-cresol sulfate (PCS), indoleacetic acid (IAA), and bilirubin (BR), respectively, in the presence of 40 g/L bovine serum albumin. Further molecular dynamics simulations and DFT calculations showed that poly-CBMA exhibited stronger intermolecular forces for all three toxins. The hydrogen bonds formed between the negatively charged carboxylate ions from PCBMA contributed to its excellent adsorption performance. This study not only provides a new idea to study the adsorption mechanism of toxins by zwitterionic polymers but also demonstrates the promising application of microspheres modified by zwitterionic polymers in clinical hemoperfusion therapy.