The effect of immobilization of thrombin inhibitors onto self-assembled monolayers on the adsorption and activity of thrombin.
Thrombus formation is the major problem associated with biomaterials for blood contact medical devices. The immobilization of inhibitors to thrombin, a serine protease that plays a central role on the coagulation system, on the surface of biomaterials should be a good strategy to avoid blood clotting and increase their hemocompatibility. The aim of this work is the design of a nanostructured surface with capacity to adsorb and inactivate thrombin. The pentapeptide sequence d-Phenylalanine-Proline-Arginine-Proline-Glycine (fPRPG), that was described as a thrombin inhibitor, was immobilized onto tetra(ethylene glycol) terminated self-assembled monolayers (EG4-SAMs). Surface containing different amounts of fPRPG were prepared using different concentrations of N,N'-Carbonyldiimidazole (CDI) during immobilization. The efficiency of fPRPG immobilization was followed using ellipsometry, contact angle measurements, Infrared reflection absorption spectroscopy (IRRAS) and X-ray photoelectron spectroscopy (XPS). Thrombin adsorption was quantified using radiolabelled thrombin and its activity in solution and after adsorption on the developed surfaces was assessed using a chromogenic assay. It was found that, although the immobilization of fPRPG on to EG4-SAMs does not increase its selectivity to thrombin, the activity of the adsorbed thrombin was inhibited in a peptide concentration dependent way. We concluded that SAMs with fPRPG immobilized in high amounts can be used as thrombin-inhibitor surfaces, which is a good step on the development of new surfaces for blood contact devices.
INEB-Instituto de Engenharia Biomédica, Divisão de Biomateriais, Universidade do Porto, Porto, Portugal.
Sidónio C
SC
Freitas
Mário A
MA
Barbosa
M Cristina L
MC
Martins
D000327:Adsorption / Q000187:drug effects; D000418:Albumins / Q000378:metabolism; D006046:Gold / Q000378:metabolism; D006801:Humans; D055767:Immobilized Proteins / Q000737:chemistry / Q000494:pharmacology*; D007457:Iodine Radioisotopes; D010455:Peptides / Q000737:chemistry / Q000494:pharmacology*; D012995:Solubility / Q000187:drug effects; D012996:Solutions; D017550:Spectroscopy, Fourier Transform Infrared; D013499:Surface Properties / Q000187:drug effects; D013917:Thrombin / Q000037:antagonists & inhibitors* / Q000378:metabolism*
D000418:Albumins; D055767:Immobilized Proteins; D007457:Iodine Radioisotopes; D010455:Peptides; D012996:Solutions; D006046:Gold; D013917:Thrombin