Structure and functional properties of Capto™ Core 700 core-shell particles

Capto™ Core 700 is a core-shell chromatographic support with an adsorbing core contained within an inert shell layer designed to purify larger biomolecules and bioparticles in a flow-through mode. The present study aims to characterize the structure and functional properties of this resin using bovine serum albumin (BSA, Mr~65 kDa) and thyroglobulin (Tg, Mr~660 kDa) as model impurity proteins. The functionalized adsorbing core and the inert shell have the same fibrous structure typical of agarose-based beads. The resin average bead size is 90.7 μm with a range of 50-130 μm, the shell thickness is 4.18 µm with a range of 3-6 µm and a standard deviation of 0.55 µm, and the pore radius, obtained by inverse size exclusion chromatography, is 50.4 ± 1.3 nm. Both proteins present highly favorable binding isotherms with maximum binding capacities of 55 and 105 mg/mL of total bead volume for BSA and Tg, respectively. The addition of 500 mM NaCl reduces the binding capacity by less than 50%, showing the ability of the resin to operate at high salt conditions. For both proteins, the effective pore diffusivity in the core is smaller than in the shell due to additional hindrance by bound protein in the core area. Effective pore diffusivities values in the core are 1.6 × 10-7 and 0.16 × 10-7 cm2/s for BSA and Tg, respectively. The DBC10% at 2 min residence time are 24 and 2 mg/mL for BSA and Tg, respectively. This study provides qualitative and quantitative information about Capto™ Core 700 resin. This information could be used to predict and optimize the purification of large biomolecules and bioparticle in route to the establishment of more effective downstream processes.