Expanded and packed bed albumin adsorption on fluoride modified zirconia

Abstract

The expanded bed characteristics of 75–103μm fluoride‐modified zirconia (FmZr) particles synthesized by a fed batch oil emulsion process were investigated. These particles are distinguished from commercially available expanded‐bed adsorbents by virtue of their high density (2.8 g/cc) and the mixed mode protein retention mechanism which allows for the retention of both cationic and anionic proteins. The linear velocity versus bed porosity data agree with the Richardson–Zaki relationship with the terminal velocity in infinite medium of 2858.4 cm/h and a bed expansion index of 5.1. Residence time distribution (RTD) studies and bovine serum albumin (BSA) adsorption studies were performed as a function of the height of the settled bed to the column diameter (H:D) ratio and degree of bed expansion with superficial velocities of 440 to 870 cm/h. The settled bed, a 2× expanded bed, and a 3× expanded bed were studied for the H:D ratios of 1:1, 2:1, and 3:1. The dynamic binding capacity (DBC) at 5% breakthrough was low (2–8 mg BSA/mL settled bed) and was independent of the H:D ratio or the degree of bed expansion. The saturation DBC was 32.3 ± 7.0 mg BSA/mL settled bed. The adsorption–desorption kinetics and intraparticle diffusion for protein adsorption on FmZr (38–75 μm) were investigated by studying the packed bed RTD and BSA adsorption as a function of temperature and flow rate. The data show that the adsorption–desorption kinetics along with intraparticle diffusion significantly influence protein adsorption on FmZr. Low residence times (∼0.8 min) of BSA result in a DBC at 5% breakthrough which is 3.5‐fold lower compared to that at 6‐fold higher protein residence time. At low linear velocity (45 cm/h) the breakthrough curve is nearly symmetrical and becomes asymmetrical and more dispersed at higher linear velocity (270 cm/h) due to the influence of slow adsorption–desorption kinetics and intraparticle diffusion.© 1998 John Wiley & Sons, Inc. Bioeng 60: 333–340, 1998.

Impact of Porogens on the Pore Characteristics of Zirconia Particles Made by Polymer-Induced Colloid Aggregation

“…6,31,32 An examination of the relationship between the size of the colloid and the pore size obtained in aggregates obtained by the spray drying process, the PICA process, or the oilemulsion process reveals that when a colloidal solution (with the colloid particle size of 100 nm (1000 Å)) was used in any of the aggregation processes listed, a pore size in the range of 1827 nm was often obtained. 3,[33][34][35] In the absence of porogen or any binder molecule, we hypothesize that the most viable arrangement of col loid particles is one in which three colloid particles are held in the cluster. The resultant pore diameter ob tained equals the equivalent diameter of the interstitial void space between colloid particles.…”

Part II. Chromatography using ultra-stable metal oxide-based stationary phases for HPLC

“…Apparently, this material acts as a ligand exchange (or metal affinity) material analogous to calcium hydroxyapatite [4]. Fluoride modified zirconia was shown to have an exceptionally high capacity for proteins [4] thus it was examined for preparative protein purification [66,67]. Washing the column with fluoride solution easily regenerates it.…”

Siloxane-based biocatalytic films and paints for use as reactive coatings

“…Protein adsorption occurs widely in natural and man-made systems, and has had a great impact on many medical, environmental, and biotechnological processes. Protein adsorption is particularly problematic in the biofouling of food processing equipment, ship hulls, medical implants, ultrafiltration membranes, and many other devices (Anderson et al, 1995;Lacasse et al, 1998;Mullick et al, 1998). Several factors are known to influence protein adsorption, such as conformational entropy of the protein, hydrophobic interactions, and electrostatic interactions (Chaiken et al, 1988;Norde, 1996).…”