Portal de Periódicos da CAPES

The activation of human plasma prekallikrein as a hemocompatibility test for biomaterials. II. Contact activation by EVAL and EVAL-SMA copolymers

1993; Taylor & Francis; Volume: 4; Issue: 6 Linguagem: Inglês

10.1163/156856293x00276

1568-5624

Giulio D. Guerra, Niccoletta Barbani, Luigi Lazzeri, L. Lelli, Maurizio Palla, Cosimo Rizzo,

Coagulation, Bradykinin, Polyphosphates, and Angioedema

The activation of human plasma prekallikrein (PKK) to kallikrein (KK), induced by the contact of blood with foreign materials, is a useful in vitro hemocompatibility test. Kallikrein is easily detected by its reaction with the chromogenic substrate H-D-Pro-Phe-Arg-pNA, which releases p-nitroaniline, revealed by its absorption at 405 nm. This test, which was already carried out by evaluating PKK activation by the 'end-point' method, has been carried out in this work by the more accurate 'initial velocity' method, i.e. by evaluating the activation from the initial rates of the KK-substrate reaction. The tests were carried out on the following materials: borosilicate glass (as a high-activation reference material), silicone (as a low-activation reference material), the commercial biomaterial Cardiothane 51, three graft copolymers synthesized in our laboratory by reacting ethylene-vinyl alcohol copolymer (EVAL) with styrene-maleic anhydride copolymer (SMA), and EVAL itself. A mathematical treatment based on a simple kinetic model has been used for a first-approximation evaluation of the PKK-activating power of the materials tested. The quite low activating power of the EVAL-SMA copolymers, which are easily processable into water-permeable hollow fibers, suggests the possibility of their use in blood dialyzers.