Agarose-Encapsulated Adsorbent Beads for Direct Hemoperfusion : Preparation and in Vitro Evaluation

Abstract

Agarose beads containing a powdered charcoal or a cation-exchange resin were prepared by dropping a hot aqueous suspension of adsorbents in agarose sol into an organic solvent mixture consisting of cyclohexane and chloroform (2 : 1). The beads were crosslinked for intended use in direct hemoperfusion circuits as adsorbent columns. Their in vitro adsorption characteristics for selected adsorbates such as theophylline, paraquat, cholate, etc., from rabbit blood as wel as from Ringer's solution were evaluated by means of batchwise adsorption experiments and by the column method. Adsorption rate rather than capacity was reduced by incorporation of the powdered adsorbent into agarose gel, particularly for larger adsorbates. On the basis of equal adsorbent weight, the cation-exchange resin beads adsorbed paraquat from Ringer's solution better than did coated petroleum-based activated carbon beads obtained from a commercial hemoperfusion column. No significant changes in the levels of plasma components were observed after contact with the blood. The degree of platelet reduction was similar for the charcoal beads and control agarose beads without an adsorbent, though that for the resin beads was slightly greater. These adsorbent-containing agarose beads are likely to be of value for blood purification.