Development and characterization biodegradable ion-exchangers based on alginate microparticles for protein purification

FUCIÑOS, PABLO; LORENZO PASTRANA; BRASSESCO, MA. EMILIA; GUILLERMO A. PICÓ

Conferencia; Polymar; 2018

I.Introduction - Ion exchange chromatography (IEC) is a versatile tool for separating proteins according to differences in their surface charge. However, IEC resins are expensive and have a short shelf life [1]. Designing new biodegradable cost-competitive IEC resins may have an enormous impact on many industrial processes involving protein purification. Alginate is a natural polymer that has the unique property of gel-formation in the presence of divalent cations such as calcium, it is also biodegradable and cost-efficient [2]. In this work, alginate microparticles were produced by nano spray drying, and further characterized regarding their physicochemical properties and adsorption capacity for two model proteins, Lysozyme (LZ) and Chymotrypsinogen (QTg).II.Experimental - Microparticles were produced using a Büchi Nano Spray Dryer B-90. A 0.1 % w/v sodium alginate solution (CR8133) was spray-dried to form microparticles. To cross-link the microparticles, 30 mg of microparticles were dispersed in 1.2 mL of a 0.1 M CaCl2 solution in EtOH and sonicated 30 min at 45ºC [3]. Epiclorhidrine (Epi) (72 µL) was then added in a basic medium (150 µL NaOH 5M) and incubated over night at 30ºC. The crosslinking was ended by adding acetic acid until the pH was 7.0.III. Results and Discussion - The microparticle?s morphology after the crosslinking process was analyzed by SEM (Image 1). The mean diameter and potential Zeta of the alginate microparticles were 648.3±811.9 nm and -83.94 ± 2.01mV. The thermogravimetric curves (TGA) for the crosslinked microparticles showed three thermal events. The first event was associated to a moisture loss, where the samples presented evaporation temperatures ranging from 30ºC to 128ºC. The other events were associated to the decomposition of the polysaccharide occurring mainly in the ranges of and 186-220ºC and 248-289ºC. The protein-adsorption capacity (Qmax) of the microparticles was studied using Qtg and LZ like models. The determined Qmax were 3034 mg/g of matrix and 1880 mg/g of matrix for Qtg and LZ, respectively.IV.Conclusions - The alginate microparticles showed a good thermal stability and an excellent adsorption capacity, even higher than some IEC resins currently available in the market, indicating a high potential for industrial application