A thiol functionalized cryogel as a solid phase for selective reduction of a cysteine residue in a recombinant human growth hormone variant.

Site selective chemical modification is a preferred method, employed to prolong the circulation half-life of biopharmaceuticals. Cysteines have been used as attachment point for such modification, however, to be susceptible for chemical modification the involved thiol must be in its reduced form. Proteins often contain disulfides, which aid to maintain their tertiary structure and therefore must remain intact.

An improved capillary model for describing the microstructure characteristics, fluid hydrodynamics and breakthrough performance of proteins in cryogel beds.

A capillary-based model modified for characterization of monolithic cryogels is presented with key parameters like the pore size distribution, the tortuosity and the skeleton thickness employed for describing the porous structure characteristics of a cryogel matrix. Laminar flow, liquid dispersion and mass transfer in each capillary are considered and the model is solved numerically by the finite difference method. As examples, two poly(hydroxyethyl methacrylate) (pHEMA) based cryogel beds have been prepared by radical cryo-copolymerization of monomers and used to test the model.