Human serum albumin adsorption on poly[(glycidyl methacrylate)-co-(methyl methacrylate)] beads modified with a spacer-arm-attached L-histidine ligand

Poly(GMA/MMA) beads were synthesized from glycidyl methacrylate (GMA) and methyl methacrylate (MMA) in the presence of a cross-linker (i.e. ethyleneglycol dimethacrylate) (EGDMA) via suspension polymerization. The epoxy groups of the poly(GMA/MMA) beads were converted into amino groups with either ammonia or 1,6-diaminohexane (i.e. spacer-arm). An L-histidine ligand was then covalently immobilized on the aminated (poly(GMA/MMA)-AH) and/or the spacer-arm attached (poly(GMA/MMA)-SAH) beads using glutaric dialdehyde as a coupling agent. Both affinity adsorbents were used in human serum albumin (HSA) adsorption/desorption studies under defined pH, ionic strength or temperature conditions in a batch reactor. The spacer-arm attached affinity adsorbent resulted in an increase in the adsorption capacity to HSA when compared to the aminated counterpart (i.e. poly(GMA/MMA)-AH). The maximum adsorption capacities of the affinity adsorbents were found to be significantly high, i.e. 43.7 and 80.2 mg g(-1) (of the beads), while the affinity constants, evaluated by the Langmuir model, were 3.96 x 10(-7) and 9.53 x 10(-7) molL(-1) for poly(GMA/MMA) -AH and poly(GMA/MMA)-SAH, respectively. The adsorption capacities of the affinity adsorbents were decreased for HSA by increasing the ionic strength, adjusted with NaCl. The adsorption kinetics of HSA were analysed by using pseudo-first and pseudo-second-order equations. The second-order equation fitted well with the experimental data. (c) 2005 Society of Chemical Industry.