Polyhydroxyethylmethacrylate-based magnetic DNA-affinity beads for anti-DNA antibody removal from systemic lupus erythematosus patient plasma

The aim of this study is to prepare magnetic poly(2-hydroxyethylmethacrylate) (mPHEMA) beads and to investigate their utility for the removal of anti-DNA antibodies from systemic lupus erythematosus (SLE) patient plasma. mPHEMA beads, in the size range of 80–120 μm, were produced by a modified suspension technique. Then, DNA was coupled onto mPHEMA beads by carbodiimide activation. The amount of ligand coupled was changed by changing the initial concentrations of carbodiimide and DNA. Human immunoglobulin G (HIgG) and anti-DNA antibody adsorption from aqueous solutions and human plasma were examined in a batch system. mPHEMA beads were characterized by swelling tests, electron spin resonance (ESR) and scanning electron microscopy. Important results obtained in this study are as follows: the swelling ratio of mPHEMA beads was 34%. The presence of magnetite particles in the polymeric structure was confirmed by ESR. The mPHEMA beads have a spherical shape and porous structure. Maximum DNA coupling of carbodiimide activated mPHEMA beads was 4.4 mg/g. Maximum HIgG adsorption from an aqueous solution was 47.5 mg/g. Anti-DNA antibody adsorption from SLE plasma was observed as 87.6 mg/g. Non-specific HIgG adsorption was 0.1 mg/g. More than 90% of the adsorbed HIgG molecules and anti-DNA antibodies were desorbed succesfully by using NaSCN solution. It was possible to reuse these DNA-affinity beads without significant losses in the antibody adsorption capacities.