Comparative studies of agarose and kieselguhr-agarose composites for the preparation and operation of...

Study was made of controlled fabrication and operation of immunoadsorbents exploiting beaded composites of agarose or kieselguhr-agarose. Materials were activated by cyanogen bromide and tresyl chloride, derivatised with human IgG antigens, and utilised in direct, one-step purifications of anti-huIgG monoclonal antibodies produced in serum-based cultures of murine hybridomas. The influence of solid phase composition, degrees of activation, concentration of immobilised antigen, capping chemistries, and mode of product desorption was studied in respect of purification performance. Maximum concentrations of immobilised huIgG could be achieved following activation of 50% available hydroxyl groups in both materials. Specific adsorption and desorption of monoclonal antibodies, expressed per mole of immobilised ligand, declined with increasing ligand concentrations. Control of activation and derivatisation of agarose solid phases enhanced the overall specification and performance of both homogeneous and composite fabricates. The large particle size of composites (150-1000 microns) restricted efficient performance in fixed bed contactors operated under non-equilibrium conditions. However, their physical nature recommended adsorptive operations with particulate feedstocks in fixed or fluidised beds, batch suspension contactors, or fast flow regimes adopted for cleaning and equilibration operations.