Adsorption of human immunoglobulin G using fibroin microparticles

Immunoglobulin G (IgG) is an antibody used in numerous therapeutic indications. For this reason, high-purity IgG is required, which implies the use of selective adsorption chromatographic purification techniques. Although, before using chromatography, it is highly important to study the interaction between IgG and the adsorbent. Due to its characteristics, biopolymeric adsorbents are widely studied. However, there are no studies in the literature that evaluate IgG adsorption onto fibroin, a natural polymer that can be used as an ion exchange adsorbent. Thus, the aim of this work was to evaluate the adsorption of human IgG on fibroin microparticles. The microparticles were prepared from fibroin solution using the atomization method, with an average diameter of 108.5 μm. Three buffers (MOPS, MES and Tris–HCl), with different pH, were used, and for the best conditions, the influence of ionic strength (NaCl from 0 to 1 mol L⁻¹), temperature (4 °C to 37 °C) and rotation (20 rpm to 40 rpm) were studied. The highest adsorption capacity (906.45 mg g⁻¹) was reached with the MOPS buffer at pH 8.0, without NaCl, 25 °C and 30 rpm, which is higher than typical adsorption capacities found in the literature for other adsorbents. The adsorption capacity reduced with increasing temperature from 25 °C to 37 °C and rotation rate from 30 to 40 rpm. The thermodynamic parameters demonstrated that adsorption is spontaneous and endothermic. These results open up new possibilities of application of fibroin microparticles, considering the medium in which they are inserted, and highlights the improvement of IgG chromatographic purification for uses in pharmaceutical field.

Graphical abstract