in u s pat no 5 567 588 1996 issued to gold et al incorporated herein by reference in its entirety in this example the isolation of fas ligand protein specific dna aptamers and the production of hollow fiber coupled aptamer affinity matrices are described purified fas ligand protein is chemically coupled to agarose using amino link agarose pierce chemical co aminolink coupling gel is a 4 crosslinked beaded agarose support activated to form aldehyde functional groups which develops a stable bond in the form of a secondary amine between the gel and the protein with coupling efficiencies of 85 between ph 4 10 in this example 2 ml fas ligand protein 1 mg ml in coupling buffer is applied to the aminolink gel for 7 hours at 4 degrees c unreacted protein is then washed off with 25 volumes of phosphate buffered saline pbs and the product material stored cold until ready for use next dna oligonucleotides typically 80 nucleotides long are prepared containing the following elements first a pcr primer site of 20 nucleotides on both the 5 u2032 and 3 u2032 ends and a 40 base segment in the middle of the molecule prepared with a random mixture of bases this generates a very large number of dna species from which the specific aptamer i e dna antibody may be selected the dna capable of binding.