Investigations on the adsorbents for uremic middle molecular toxins (II) - Influences of crosslinking agent chain length on the adsorption capacities of crosslinked chitosan adsorbents

Chitosan resins, which clinically served as adsorbents in hemoperfusion therapy, were prepared with reversed-phase suspension methodology using three differently structured crosslinking agents, methanol, glyoxal and glutaraldehyde. And the glyoxal and glutaraldehyde crosslinked chitosan resins were reduced with NaBH₄ afterwards. By analyzing the results from FTIR and SEM, it was found that the reduction treatment to the adsorbents efficiently improved the chemical stability of these chitosan resins, and the shifts in crosslinking agents exerted influences over the morphologies of the adsorbents obviously. After being put to use in the adsorption tests upon some model uremic middle molecular toxins and BSA in vitro, all three adsorbents demonstrated a fairly realistic adsorption capability to the model toxins but little to BSA. And the adsorption process reached the equilibrium in a clinically qualified short time. But the adsorption capacities of these adsorbents to the model toxins were quite different. It had been found that with the growing of fatty chain length of crosslinking agent, these adsorbents showed a gradually increased adsorption capacity to the model toxins, and the glutaraldehyde crosslinked chitosan resin behaved best.