METHOD FOR MAKING HEPARINIZED BIOMATERIALS

An improved method of making a medical device having immobilized heparin on a blood-contacting surface in which heparin is admixed with sufficient periodate to react with not more than two sugar units per heparin molecule in a buffer solution having a pH in the range of about 4.5-8. This mixture is reacted for at least 3 hours while protected from light and is then applied to the immobilized amine groups. This is an improvement over the prior art methods which included using an excess of periodate and then stopping the reaction at a desired point by the addition of glycerol since the conversion of only a few of the natural functional groups to aldehydes better preserves the antithrombotic bioeffectiveness of the heparin molecules bound to the surface. The invention also avoids the prior art steps of drying and reconstituting the heparin by providing a reacted mixture of heparin and periodate that can be stored as a stable liquid and applied directly to the aminated surface several days later.