Protamine immobilization and heparin adsorption on the protamine‐bound cellulose fiber membrane

Abstract

Immobilization of protamine to the inner lumen of cellulose hollow fibers has been shown useful in preventing both heparin-and protamine-induced complications during an extracorporeal blood circulation procedure. The current study examined the effects of variables on the immobilization of protamine to cyanogen bromide (CNBr)-activated cellulose hollow fibers. The degree of protamine immobilization was controlled by three independent parameters: the amount of CNBr used during the activation process, the duration of the coupling process, and the protamine concentration in the coupling solution. By the adjustment of these parameters, cellulose fibers containing desired amounts of immobilized protamine (ranging from 1 to 20 mg of immobilized protamine per gram of dry fibers) were readily prepared.Heparin adsorption to the protamine-bound cellulose fibers was also examined. The adsorption isotherm followed a Langmuir adsorption model. The amount of heparin adsorbed was dependent on both the heparin concentration in the substrate solution and the protamine loading on the fibers. The Langmuir adsorption constant K was estimated to be 0.37 k0.06 mL/mg, whereas the saturation capacity 0, of the protamine-bound fibers increased with increasing the protamine loading.

A Protamine-Coated Device for the Control of Heparin Anticoagulation

“…The feasibility of such an approach has been successfully demonstrated. A prototype protamine filter was developed by coupling protamine onto the inner walls of regenerated cellulose hollow fibers, using cyanogen bromide activation (15). Regenerated cellulose hollow fibers, widely used in hemodialyzers, were selected because of their proven blood compatibility.…”

“…Regenerated cellulose hollow fibers, widely used in hemodialyzers, were selected because of their proven blood compatibility. A detailed, systematic investigation of variables affecting protamine immobilization was conducted in order to establish an optimized immobilizaion process (15,16). Using such optimized procedures, fibers containing desired amounts of immobilized protamine ranging from 5 to 20 mg protamine per gram of fiber dry weight was readily prepared (15)(16)(17).…”

“…A detailed, systematic investigation of variables affecting protamine immobilization was conducted in order to establish an optimized immobilizaion process (15,16). Using such optimized procedures, fibers containing desired amounts of immobilized protamine ranging from 5 to 20 mg protamine per gram of fiber dry weight was readily prepared (15)(16)(17). In vitro characterization of the protamine filter showed that heparin adsorption on the protamine-bound fibers followed a Langmuir adsorption model (15); the amount of heparin adsorbed was dependent on both the heparin concentration in the solution and the protamine loading on the fibers.…”

“…Using such optimized procedures, fibers containing desired amounts of immobilized protamine ranging from 5 to 20 mg protamine per gram of fiber dry weight was readily prepared (15)(16)(17). In vitro characterization of the protamine filter showed that heparin adsorption on the protamine-bound fibers followed a Langmuir adsorption model (15); the amount of heparin adsorbed was dependent on both the heparin concentration in the solution and the protamine loading on the fibers. The Langmuir adsorption constant of the immobilized protamine was estimated to be 0.37 ± 0.06 mL/mg, whereas the saturation capacity of the protamine filter increased…”

“…A time-dependent decrease in heparin removing efficiency by the protamine filter was observed both in vitro and in vivo (15,17), indicating that the protamine filter gradually became saturated. To maintain a continuous effective heparin removal the future system needs to consist of multiple protamine filters so that one filter is removing heparin while the others are being regenerated.…”