High-hydrostatic pressure technique is an effective method for the preparation of PVA–heparin hybrid gel

To develop an antithrombotic material for preparation of small-diameter vascular graft, we describe a novel method to prepare a poly(vinyl alcohol) (PVA)–heparin hydrogels prepared by high-hydrostatic pressure (HHP, 980 MPa), which is designed for sustained release of heparin. Antithrombogenic test revealed that HHP method would not affect the antithrombin III (ATIII) activity of the released heparin. The distribution of heparin in the polymer matrix was homogeneous than freeze–thawing gel, due to the fast gelling affect of PVA which takes approximately 10 min for gel formation. The formation of intra- and intermolecular hydrogen bonds between PVA chains has trapped the heparin inside, suppressing the phase separation between PVA and heparin. Furthermore, evenly distribution of heparin induced the formation of heparin and PVA molecular complex, which brought the sustained release of heparin from the PVA despite the high swelling ratio. Our results show that it is possible to prepare a PVA–heparin hybrid gel which can be applied as an effective material for an antithrombotic system without using any chemical agent.