Preparation and adsorption behavior of a cellulose‐based, mixed‐mode adsorbent with a benzylamine ligand for expanded bed applications

Abstract

A novel mixed-mode expanded bed adsorbent with anion-exchange properties was explored with benzylamine as the functional ligand. The cellulose composite matrix, densified with stainless steel powder, was prepared with the method of water-in-oil suspension thermal regeneration. High activation levels of the cellulose matrix were obtained with allyl bromide because of the relative inertness of the allyl group under the conditions of the activation reaction. After the formation of the bromohydrin with N-bromosuccinimide and coupling with benzylamine, the activated matrix was derived to function as a mixed-mode adsorbent containing both hydrophobic and ionic groups. The protein adsorption capacity was investigated with bovine serum albumin as a model protein. The results indicated that the prepared adsorbent could bind bovine serum albumin with a high adsorption capacity, and it showed salt tolerance. Effective desorption was achieved by a pH adjustment across the isoelectric point of the protein. The interactions between the cell and adsorbent were studied, and the bioadhesion was shielded by the adjustment of the salt concentration above 0.1M. Stable fluidization in the expanded bed was obtained even in a 2% (dry weight) yeast suspension. The direct capture of target proteins from a biomass-containing feedstock without extra dilution steps could be expected with the mixed-mode adsorbent prepared in this work, and this would be especially appropriate for expanded bed adsorption applications.

High-throughput isotherm determination and thermodynamic modeling of protein adsorption on mixed mode adsorbents

“…In the proposed thermodynamic treatment of mixed mode protein adsorption, the following mixed mode interaction stoichiometry is assumed, P + vSL + nL ⇔ PL n + vS (4) in which a protein molecule P can interact with n hydrophobic ligands and simultaneously exchange with v salt counter-ions on the resin surface to form the protein-ligand complex PL n . The thermodynamic equilibrium constant can be written in terms of the activities of the species or the standard Gibbs energy change of association as:…”

“…Gao et al [4,14,15] investigated mixed mode adsorbents functionalized with benzylamine ligand for expanded bed applications, using bovine serum albumin (BSA) as a model protein. The adsorbents showed salt-tolerant and pH-dependent protein binding and effective protein desorption by charge repulsion [14,15].…”

“…Most mixed mode resins used for protein applications are functionalized with ligands exhibiting both hydrophobic and electrostatic properties [4][5][6]. The electrostatic part can effect adsorption at low to moderate conductivities while the hydrophobic part does so at moderate to high conductivities, thereby extending the range of selectivity of the adsorbent [5].…”

Evaluation of protein adsorption and preferred binding regions in multimodal chromatography using NMR

“…In addition, several libraries of MM ligands have been recently developed and employed on chromatographic resins for screening with biological mixtures. Applications of this technology range from preparative protein purifications (11,12) to front end separations for mass-spectrometry analysis (13,14).…”

Cross-linked κ-carrageenan polymer/zinc nanoporous composite matrix for expanded bed application: Fabrication and hydrodynamic characterization

“…Expanded bed adsorption (EBA) is a special chromatographic technique with a solid phase (adsorbent) of defined density and size distribution, which provides the potential advantages of both packed bed and fluidized bed [1,2]. Due to simplicity of EBA as a single step operation for purification of different proteins, it has been greatly adopted for initial recovery of protein purification from crude feedstocks including particulate suspended matter [3][4][5].…”