Poly-l-lysine modified cryogels for efficient bilirubin removal from human plasma

In this study, poly-l-lysine (PLL) immobilized PHEMA cryogel was designed for the specific bilirubin removal from human plasma. The surface of PHEMA cryogels is surrounded by PLL chains to enhance specific binding of bilirubin molecules via specific complementary electrostatic interactions. The functionalization of the PHEMA cryogel was carried out by direct coupling of PLL to pre-activated OH-group of the HEMA alcohol units via carbodiimide activation. Prior to removal of bilirubin from human plasma, the optimization parameters including, initial bilirubin concentration, flow rate, temperature, ionic strength, and adsorption rates on adsorption of PLL-PHEMA cryogel were investigated from the aqueous medium. According to the elemental analyses results, the incorporation of PLL was 690.0 μmol/g cryogel. The cryogel has highly interconnected supermacroporous structure sized between 20 and 100 μm with a positive surface charge value. The maximum bilirubin adsorption capacity was found as 59.9 mg/g of the dry weight of PLL-PHEMA cryogel. Reusability study explored that PLL-PHEMA could be used with a negligible loss in the bilirubin adsorption capacity after successive ten adsorption-desorption cycles using the same adsorbent. The results of the study demonstrated that the PLL-PHEMA cryogel exhibited high specificity that can be used as an efficient column for removing the bilirubin from the human plasma.