Coating membranes for a sorbent-based artificial liver: adsorption characteristics.

Techniques are described for the coating of sorbents to be used in an artificial liver support system based on mixed sorbent bed hemoperfusion. Activated charcoal has been coated with cellulose acetate (CA) by solvent evaporation. With Amberlite XAD-4, the Wurster technique was used for coating with CA. XAD-4 has also been coated with a synthetic polyelectrolyte with anticoagulant activity by adsorption and fixation by gamma radiation-induced crosslinking. Activated charcoal, XAD-4, and a cation exchange resin, all in powdered form, were encapsulated in agarose gel beads. Adsorption characteristics onto the sorbents are described. The results are in agreement with a theoretical model presented. In general, adsorption onto XAD-4 is limited by film diffusion. With activated charcoal, pore diffusion limitation is generally observed. Blood compatibility is improved by coating.