The Preparation Of Agarose Coated Activated Carbon And Endotoxin Adsorbent

Endotoxins can cause a variety of biological effects. The most typical one is called endotoxemia. When suffering from endotoxemia, endotoxin can stimulate macrophages, neutrophils, endothelial cells, platelets, coagulation system, complement system and so on, which lead to microcirculation disorder, shock, and more seriously, multiple system organ failure or death. Therefore, it is of great significance for development of absorbent with the ability of effectively removing endotoxin.In this paper, in order to synthesize absorbent for endotoxin with ability of synergistic adsorption, the activated carbon was coated with agarose, and coupled with a series of ligands. The synthetic conditions were optimized and its adsorption mechanism and adsorption property were researched simultaneously. The results were listed as follows:In the process of synthesizing agarose coated activated carbon, reaction system was the most stable when the stirring speed was600rpm, volume ratio of aqueous phase to oil phase was1:3.5, the concentration of surfactant was6%, and HLB was6.5. In this condition, the coating reaction also proceeded smoothly.The thickness of membrane coated on activated carbon surface was moderate when concentration of agarose was4%-6%(m/v). When the ratio of epichlorohydrin’s volume to activated carbon’s weight was0.39:1(v/m), the synthesized cross-linked agarose coated activated carbon can withstand moist heat sterilization.In human serum, considering the absorption capacity of endotoxin, total protein recovery and albumin recovery, absorbent coupled with s-polylysine (PLL) and lysine (Lys) simultaneously was better than the others. When the concentration of ligand was55μmol/g, the absorption capacity of endotoxin was38.06EU/g and clearance was55.4%at an initial endotoxin concentration of3.43EU/mL.With increasing ionic strength, electrostatic interaction between the endotoxin and adsorbent gradually decreases; With increasing pH, electrostatic interaction between the endotoxin and adsorbent also decreases gradually; The higher the temperature, the faster the Brownian motion of molecules, the higher the probability of endotoxin collision with the adsorbent, the more favorable for the absorption. In Tris-HCl buffer solution, adsorption equilibrium can reach within60min at37℃. The adsorption kinetics of absorbent was in accordance with second order kinetic equation and the results showed that the isotherm of absorbent was in accordance with Freundlich equation. The saturated adsorption capacity was more than2200EU/g.Considering absorption capacity and clearance rate of the adsorbent for endotoxin, the ratio of absorbent’s weight to serum’s volume was appropriate at1:20.In human serum, the results of adsorption experiment demonstrated that, although the clearance rate was merely46%, adsorbent developed in this study still had advantage of lower price than other adsorbents. In addition, the adsorbent had the ability of removing inflammatory cytokines, which other adsorbent did not.