Patent ID: 8070958

Claim:
In a method of providing a separation matrix comprising ligands coupled to the surfaces of a porous support; the method comprising providing the porous support comprising porous particles; and coupling ligands to the surface of said porous support, wherein the ligands provide at least one ligand density gradient in the support, further wherein the ligand density gradient(s) extend between the center and the exterior surface of each porous particle; the improvement comprises providing said at least one ligand density gradient by solvent-controlled diffusion of at least one reagent into the porous support, wherein the solvent-controlled diffusion is obtained by contacting a first solvent comprising said reagent(s) with the support, in the pores of which a second solvent is present, said first and second solvents presenting different solubilities wherein the support presents activated groups; and, wherein a ligand density gradient that increases or decreases towards the center of the support is provided by diffusion-controlled addition to the porous support of a first reagent, which comprises deactivating groups, to deactivate in a controlled fashion some of the surface groups of the support, and subsequent addition of another reagent, which comprises at least one functionality, to couple said at least one functionality to the surface groups that have not been deactivated.