Objective To design and prepare a high efficiency bilirubin adsorbent with good mechanical properties and biocompatibility.Methods In this study,quaternary ammonium pyridine was designed and synthesized,and then modified polyether sulfone microspheres,or PES/p(4-VP-co-N-VP)@6 microspheres,were prepared by phase conversion and electrostatic spraying.The morphology of the polymer components and the microspheres were studied by means of nuclear magnetic resonance(NMR)spectroscopy and scanning electron microscopy.The basic properties of the microspheres and their bilirubin adsorption efficiency were tested,and the adsorption mechanism was further explored.Blood cell counts and the clotting time of the microspheres were also measured.Results The diameter of the modified polyether sulfone microspheres prepared in the study was approximately 700-800 μm.Compared with the original PES microspheres,the surface and internal structure of PES/p(4-VP-co-N-VP)@6 microspheres did not change significantly,and they also had a loose porous structure,with some micropores scattered around in addition to irregular large pores.Compared with the control group,the bilirubin removal effect of the modified microspheres was(94.91±0.73)%after static adsorption in bilirubin PBS buffer solution for 180 min,with the difference being statistically significant(P＜0.0001).According to the findings for the clotting time,the activated partial thromboplastin time(APTT)of the blank plasma group,the control PES group,and the modified PES microsphere group were(27.57±1.25)s,(28.47±0.45)s,and(30.4±0.872)s,respectively,and the difference between the experimental group and the other two groups was statistically significant(P＜0.01,P＜0.05).There was no significant change in red blood cell and white blood cell counts.Conclusion The microspheres prepared in the study have high efficiency in bilirubin adsorption,excellent mechanical properties and thermal stability,and good blood biocompatibility,and are expected to be used in the clinical treatment of patients with liver failure.