Synthesis of Poly[(hydroxyethyl methacrylate)-co-(methacrylamidoalanine)] Membranes and Their Utilization as an Affinity Sorbent for Lysozyme Adsorption

Abstract

Various adsorbent materials have been reported in the literature for protein separation. We have developed a novel and new approach to obtain high protein-adsorption capacity utilizing a 2-methacrylamidoalamne-containing membrane. An amino acid ligand 2-methacrylamidoalanine (MAAL) was synthesized from methacrylochloride and alanine. Then, poly[(2-hydro-xyethel methacrylate)-co-(2-methacrylamidoalanine)] [p(HEMA-co-MAAL)] membranes were prepared by UV-initiated photopolymerization of HEMA and MAAL. The synthesized MAAL monomer was characterized by NMR spectrometry. p(HEMA-co-MAAL) membranes were characterized by swelling studies, porosimeter, scanning electron microscopy,FT-IR spectroscopy and elemental analysis. These membranes have large pores; the micropore dimensions are around 5-10 mum. p(HEMA-co-MAAL) affinity membranes with a swelling ration of 198.9%, and containing 23.9 (mmol MAAL).m(-2) were used in the adsorption of lysozyme (0.1-3.0 mg.ml(-1)) and at different pH values (4.0-8.0). The effect of Cu(II) incorporation on lysozyme adsorption was also studied. The non-specific adsorption of lysozyme on the pHEMA membranes was 0.9 mug-cm(-2). Incorporation of MAAL molecules into the polymeric structure significantly increased the lysozyme adsorption up to 2.96 mg.cm(-2). The lysozyme-adsorption capacity of the membranes incorporated with Cu(III) (9.98 mg.cm(-2)) was greater than that of the p(HEMA-co-MAAL) membranes. More than 85% of the adsorbed lysozyme was desorbed in 1 h in the desorption medium containing 1.0 M NaCl. The p(HEMA-co-MAAL) membranes are suitable for repeated use for more than 5 cycles without noticable loss of capacity. These features make p(HEMA-co-MAAL) membrane a very good candidate for bioaffinity adsorption. Adsorption rates of lysozyme: MAAL loading: 23.9 mmol.m(-2); pH: 7.0; temperature: 20 degreesC; total external membrane surface area in each batch: 100 cm(2).l(-1); Each point is the average of five parallel studies.