Anionic glycosylated polysulfone membranes for the affinity adsorption of low-density lipoprotein via click reactions

An anionic glycosylated polysulfone (PSf) membrane was prepared as a high-affinity adsorbent for low-density lipoprotein (LDL). The UV-induced grafting of acrylic acid to the membrane was followed by amidation and a 'thiol-yne' click reaction to achieve glycosylation and sulfonation. Membrane modification was confirmed by attenuated total reflectance-Fourier transform infrared spectroscopy and X-ray photoelectron spectroscopy. These tests revealed that the chemical compositions of the membranes' surfaces were easily regulated by controlling the 'thiol-yne' click reaction through the feed ratio of 2,3,4,6-tetra-O-acetyl-1-thio-β-d-glucopyranose and sodium 3-mercapto-1-propanesulfonate. LDL adsorption and desorption rates were estimated using an enzyme-linked-immunosorbent assay, which revealed that the obtained anionic glycosylated PSf membrane had a higher affinity for LDL than either glycosylated or sulfonated membranes alone. The combination of glycosyl and sulfonyl groups enhanced the membranes' affinities for LDL. The modified PSf membrane had an excellent biocompatibility and adsorbed a large amount of LDL, making it a promising material for LDL apheresis.

Low-density lipoprotein (LDL) adsorbents normally contain negative charged ligand to induce electrostatic interaction with the positively charged regions of LDL. Furthermore, saccharide is another common component which share in most of the LDL-adsorbents and the LDL-receptor (LDLR). Such structural similarity impels us to investigate the synergistic effect of anionic and saccharide on LDL recognition. For this purpose, an anionic glycosylated membrane of which surface composition can be controlled by click reaction with mutable glycosyl/sulfonyl ratios was prepared. The obtained membrane showed better LDL adsorption/desorption property and the adsorption amount for LDL at an optimum feed ratio. This finding highlights the role of synergistic effect of anionic and saccharide, which offer a new strategy for designing LDL adsorbent with high efficiency.