Synthesis and endotoxin removal properties of a novel affinity sorbent with poly(1-vinylimidazole) as the ligand

In this paper, a novel silica gel affinity sorbent with poly(1-vinylimidazole) (PVI) ligand was prepared for the selective removal of endotoxin (LPS) from a water or a BSA solution. The vinyl silane-modified porous silica gel particle SiO2-g-KH570 was used as macromonomer, and PVI was grafted on by heterogeneous graft copolymerization. First, the effect of reaction conditions on the grafted degree (GD) of PVI was investigated in detail by thermogravimetry. Then, the influences of initial LPS concentration, pH and ionic strength of the tested aqueous solutions on LPS removal ability of PVI-g-SiO2 affinity sorbent were studied and compared with those of His-g-SiO2 affinity sorbent. The results showed that maximum LPS removal capacity was obtained with a GD about 2.5 wt% and the PVI-g-SiO2 affinity sorbent had better selective removal of LPS compared to His-g-SiO2 affinity sorbent in both water and BSA solution. The affinity mechanism between PVI and LPS is also discussed in this paper. All of our results indicate that PVI is a good ligand for LPS removal.