The activation of human plasma prekallikrein as a hemocompatibility test for biomaterials. II. Contact activation by EVAL and EVAL-SMA copolymers.
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.
Guerra
G D
GD
Centro Studi Processi Ionici di Polimerizzazione, CNR, Pisa, Italy.
Barbani
N
N
Lazzeri
L
L
Lelli
L
L
Palla
M
M
Rizzo
C
C
D000595:Amino Acid Sequence; D001672:Biocompatible Materials; D004789:Enzyme Activation; D006801:Humans; D008299:Maleic Anhydrides / Q000737:chemistry*; D008969:Molecular Sequence Data; D011137:Polystyrenes / Q000737:chemistry*; D011145:Polyvinyls / Q000737:chemistry*; D011288:Prekallikrein / Q000378:metabolism*
D001672:Biocompatible Materials; D008299:Maleic Anhydrides; D011137:Polystyrenes; D011145:Polyvinyls; C020320:ethylene-vinyl alcohol copolymer; C025704:Styromal; D011288:Prekallikrein