Reduced leaching of a ligand

Abstract

A column for removal of a component from a fluid is disclosed. The column has a compartment with a cross sectional area. The compartment contains beads having a diameter. A ligand selected to bind to the component is coupled to the beads. The cross-sectional area and bead diameter are selected to maintain a flow velocity of the fluid within the compartment below a first threshold, thereby reducing leaching of the ligand into the fluid. Also described herein is an adsorbent comprising a ligand that is attached to a substrate by an amine bond, wherein the ligand is resistant to dissociation from the substrate.

What is claimed is: 
     
         1 . A column for removal of a component from a fluid, the column comprising:
 a compartment comprising a cross-sectional area;   a bead having a diameter and disposed within the compartment; and   a ligand coupled to the bead and selected to bind to the component; 
wherein the cross-sectional area and bead diameter are selected to maintain a flow velocity of the fluid within the compartment below a first threshold. 
     
     
         2 . The column of  claim 1 , wherein the bead comprises a plurality of ligands. 
     
     
         3 . The column of  claim 2 , wherein the ligand comprises a portion of Tumor Necrosis Factor alpha (TNF-alpha). 
     
     
         4 . The column of  claim 3 , wherein the ligand comprises a trimer of the portions of TNF-alpha. 
     
     
         5 . The column of  claim 1 , wherein the first threshold is selected so as to maintain an amount of the ligand in the fluid flowing out of the outlet below a predetermined level. 
     
     
         6 . The column of  claim 1 , wherein the first threshold is selected so as to maintain a force applied by the fluid to the ligand below a second threshold, thereby reducing leaching of the ligand into the fluid. 
     
     
         7 . The column of  claim 6 , wherein:
 the ligand comprises a bond having a strength; and   maintaining the force below the second threshold avoids breaking the bond.   
     
     
         8 . The column of  claim 7 , wherein:
 the bead comprises agarose; and   the bond comprises an amine bond.   
     
     
         9 . The column of  claim 6 , wherein:
 the force comprises one or more of a shear force and a moment; and   the second threshold comprises one or more of a third threshold related to the shear force and a fourth threshold related to the moment.   
     
     
         10 . The column of  claim 1 , wherein:
 the compartment further comprises an inlet, an outlet, and a flow path from the inlet to the outlet;   the flow path has a length; and   the length is selected to provide a contact time between the fluid and the ligand.   
     
     
         11 . The column of  claim 1 , wherein:
 the bead comprises a plurality of beads; and   the ligand comprises a plurality of portions of ligand respectively coupled to each of the plurality of beads.   
     
     
         12 . The column of  claim 1 , wherein the ligand is non-detachably coupled to the beads. 
     
     
         13 . A ligand for removal of a component from a fluid, the ligand comprising:
 at least two monomers each comprising a site that will couple to the component;   a first linker coupled by chemical bonds between two of the monomers; and   a second linker coupled by chemical bonds between one of the monomers and a substrate.   
     
     
         14 . The ligand of  claim 13 , wherein the ligand comprises three and only three monomers. 
     
     
         15 . The ligand of  claim 13 , wherein the ligand comprises two and only two first linkers. 
     
     
         16 . The ligand of  claim 13 , wherein the ligand comprises one and only one second linker. 
     
     
         17 . The ligand of  claim 16 , wherein the second linker comprises an amine bond. 
     
     
         18 . The ligand of  claim 13 , wherein the monomer comprises a site that will bind to a cytokine receptor. 
     
     
         19 . The ligand of  claim 13 , wherein the monomer comprises tumor necrosis factor alpha (TNF-alpha). 
     
     
         20 . A column for use in removing a component from a fluid, the column comprising:
 a compartment;   a bead disposed within the compartment, the bead comprising: 
 a substrate; and 
 a ligand coupled to the substrate, the ligand comprising: 
 at least two monomers each comprising a site that will couple to the component; 
 a first linker coupled by chemical bonds between two of the monomers; and 
 a second linker coupled by chemical bonds between one of the monomers and the substrate. 
 
   
     
     
         21 . A method of preparing an apheresis particle, comprising the steps of:
 oxidizing a substrate;   forming a Schiff base between a ligand comprising a portion of Tumor Necrosis Factor alpha (TNF-alpha) and the oxidized substrate; and   converting the Schiff base to a secondary amine bond.   
     
     
         22 . The method of  claim 21 , wherein the step of oxidizing a substrate comprises exposing the substrate to an inorganic salt. 
     
     
         23 . The method of  claim 22 , wherein the inorganic salt comprises sodium metaperiodate. 
     
     
         24 . The method of  claim 21 , wherein the step of converting the Schiff base to a secondary amine bond comprises exposing the substrate to a reducing agent. 
     
     
         25 . The method of  claim 24 , wherein the reducing agent comprises sodium cyanoborohydride.