a porous shaped substrate such as a porous bead is formed from polyacrylonitrile or a copolymer thereof containing nitrile groups . the substrate has a hydrophilic surface containing amide groups constituting about 1 . 8 mole percent to less than about 15 mole percent of the total nitrile groups , and containing no amide or carboxyl groups . the substrate is substantially non - swellable in water and is able to resist pressures in a columnar bed of up to about 3000 psi without collapsing . in forming the amide groups , polyacrylonitrile or copolymer thereof containing nitrile groups , an alkaline catalyst such as sodium hydroxide and a nonsolvent for the substrate such as methanol are combined to form a suspension . a peroxide is added to the suspension and the suspension is heated to hydrolyze nitrile groups to amide groups . succinylated aminoethyl groups or activated carboxyl groups can be formed on the substrate and a bioactive ligand such as p - aminobenzamidine covalently bonded to the substrate . the bound ligand can then be used to complex a biologically active substance such as an enzyme to separate the substance from solution .