Development of supermacroporous monolithic adsorbents for purifying lectins by affinity with sugars

Affinity techniques are frequently used to purify biocompounds, because of specific interactions observed in many cases. One example are the lectins, proteins connected in a reversible manner and specific to carbohydrates or sugar-containing molecules. Four different methods were investigated (epoxy, Schiff base, glutaraldehyde and ethylenediamine) to immobilize the carbohydrate N-acetyl-d-glucosamine (d-GlcNAc) on the surface of supermacroporous cryogels made for lectin purification. The glutaraldehyde method presented the highest immobilization capacity of d-GlcNAc (147.77mg/g), while the ethylenediamine method presented the lowest capacity (32.47mg/g). FTIR spectra analysis confirmed the presence of the immobilized carbohydrate. The cryogels containing d-GlcNAc immobilized by the different methods were characterized in terms of swelling capacity, degree of expansion, porosity and constituent fractions. Results showed that the activation methods did not affect the macroporous structure. Images obtained from scanning electron microscopy evidenced the presence of interconnected macropores in the structure of the cryogels produced. The cryogels presented even lower flow resistance in the permeability analysis. Finally, the cryogel modified by the glutaraldehyde method was used in the Concanavalin A lectin adsorption process, presenting an adsorptive capacity of 44.49mg/g and high stability after five cycles of use.