Human IgG adsorption using dye-ligand epoxy chitosan/alginate as adsorbent: influence of buffer system

The aim of this work was to evaluate the ability of Cibacron Blue F-3GA dye-ligand chitosan/alginate epoxide on human IgG adsorption under different buffer systems at 25 mmol L-1: Morpholinoethane sulfonic acid, morpholinopropane sulfonic acid, hydroxyethylpiperazine ethanesulfonic acid and tris-hydroxymethyl aminomethane (Tris-HCl). Batch adsorption studies were performed in order to evaluate the effect of buffer pH and nature on IgG uptake as well the equilibrium isotherms. Chromatographic experiments were performed with both human IgG (high purity) and human serum and each buffer with NaCl 1.0 M was used in the elution step. Best results (maximum equilibrium adsorption capacity of 110.9 mg g(-1)) were found at pH 7.8 with Tris-HCl buffer. The Langmuir-Freundlich model provided a good fit for the adsorption isotherm. In chromatographic experiments with high purity IgG and Tris/HCl buffer, IgG dynamic adsorption capacity onto E-Ch/Al-Cibacron was 13.4 mg g(-1), which accounted for 60 % of IgG injected into the column. Chromatographic experiments with diluted (tenfold) human serum were conducted and it was found by electrophoresis that IgG is preferentially adsorbed with respect to other proteins using all buffers systems, especially with Tris-HCl. The amount of desorbed protein from E-Ch/Al-Cibacron was around 7.0 mg g(-1) for all buffers. The new stationary phase showed high affinity for IgG and may be a potential adsorbent for human IgG purification.