γ-Cyclodextrin–polyurethane copolymer adsorbent for selective removal of endotoxin from DNA solution

Abstract

Copolymer particles for removal of endotoxins (lipopolysaccharides, LPSs) were prepared by suspension copolymerization of γ-cyclodextrin (CyD) and 1,6-hexamethylenediisocyanate. The LPS-removing activity of the copolymer particles was compared with that of poly(ε-lysine)-immobilized Cellufine (cationic adsorbent) or polystyrene particles (hydrophobic adsorbent) by a batch method. When DNA was present in solution with LPSs under physiological conditions (pH 6.0, ionic strength of μ=0.05–0.8), LPS-removing activity of the cationic or hydrophobic adsorbent was unsatisfactory because both the DNA and the LPSs were adsorbed onto each adsorbent. By contrast, the copolymer particles with γ-CyD cavity (CyD content: 14–20mol%) could selectively remove LPSs from a DNA solution (50μgml−1, pH 6.0, and μ=0.05–0.2) containing LPSs (15EUml−1) without the adsorption of DNA. The residual concentration of LPSs in the treated DNA solution was below 0.1EUml−1, and the recovery of DNA was 99%.