Antithrombogenic cellulose film

A careful solvent‐exchange procedure followed by liquid‐phase reaction of ethyleneimine with cellulose film in a nonpolar solvent provides an effective method of uniformly aminoethylating cellulose. The protonated aminoethyl groups on the cellulose can then ionically bind heparin, a blood anticoagulant. Heparinized aminoethylated cellulose tubing at low levels of aminoethylation (ca. 0.2–0.3% nitrogen) exhibited excellent antithrombogenic properties as well as excellent mechanical strength properties. The in vitro tests demonstrated indefinitely long whole‐blood clotting times with normal thrombin times. In the in vivo experiments, the heparinized aminoethylated cellulose tubing provided extended patency when implanted intravascularly in the regions of low blood flow rate (infra renal inferior vena cava of dogs). A principal use of this film is in the artificial kidney.