Biomaterials

Thrombosis induced by biomaterials after their contact with blood is a main reason of medical device failure. To make material surface more thromboresistant different approaches have been undertaken. NO generating biomaterial has proven to play a crucial role in the prevention of thrombosis by inhibiting the platelets activation/adhesion. However, immobilization of the direct thrombin inhibitors onto material surface makes material more thromboresistant by preventing thrombin-mediated blood clotting. The aim of this research was to immobilize argatroban a direct thrombin inhibitor with reliable and predictable anticoagulant effect onto PVC and PU polymers. Both polymers were first imprinted with Cu ions for the catalytic generation of NO (this research was reported earlier). Argatroban was immobilized on the Cu modified PVC and PU using the polydopamine ad-layer via the Michael addition/Schiff base reaction. The amount of argatroban bound to the polymer surface was measured (spectrophotometric determination at 334 nm) as 11.92 nmol/cm2 on PVC and 13.10 nmol/ cm2 on PU surface. Assay using thrombin specific chromogenic substrate was performed to evaluate the thrombin inhibition capacity of argatroban-modified polymers. It was found that both Argatroban-modified polymers inhibit thrombin activity in PBS. In order to confirm the NO generation catalyzed by Cu/Arg-modified PVC and PU samples after incubation with 100 μM GSNO/GSH in the PBS during 1h was examined using ArrowSTRAIGHT™ nitric oxide measurement system (Lazar Research Laboratories, Los Angeles, CA, USA). The Cu/Arg-modified PVC and PU generate NO with the rate 1.27-1.66×1010 mole/cm2∙min which is within the physiological level. From the data obtained it’s possible to conclude, that immobilization of Argatroban to the Cu-modified polymers showed combine abilities: i) generate NO caused by Cu ions and ii) have capacity to inhibit thrombin formed in the blood via surface immobilized argatroban