Contact Activation of Factor XII by Biomaterial Surfaces

Open Access
- Author:
- Yeh, Chyi-huey Joshua
- Area of Honors:
- Materials Science and Engineering
- Degree:
- Bachelor of Science
- Document Type:
- Thesis
- Thesis Supervisors:
- Erwin A Vogler, Thesis Supervisor
Evangelos Manias, Thesis Honors Advisor - Keywords:
- Contact activation
blood coagulation
blood factor XII
Hageman factor
plasma assay
chromogenic assay
ion-exchange resins - Abstract:
- The contact activation of blood factor XII or Hageman factor is studied with various material surfaces exhibiting various surface chemistry and water wettability. Experimentation revealed unidentified -activated FXII (FXIIa) protein fragments produced by material surfaces exhibiting a surface energy ranging from hydrophobic to hydrophilic properties. Both plasma coagulation assays and chromogenic assays were performed. Plasma coagulation assays detected blood factor activity that induces coagulation and chromogenic assays only detected cleavage of amino acid bonds in s-2303 chromogen. A parabolic trend was observed when putative FXIIa yield was plotted against surface energy (τ_s^°=γ_lv^° cos〖θ_s 〗 where τ_s^°, γ_lv^°, θ_s, represents the surface energy, water adhesion tension, and advancing contact angle, respectively). Surfaces were characterized as either “Type I”, “Type II”, or “Type 0” activators based on putative FXIIa yield. Both Type I and II activators had a high yield of FXIIa, but Type 0 had a significantly lower FXIIa yield. This suggested the presence of procoagulant, suppressive, and non-procoagulant amidolytic protein fragments produced by contact activation of FXII (see Chapter 2 citations). In addition to the investigation of surfaces spanning the full-range of observable water wettability, ion-exchange surfaces were also studied. Ion-exchange surfaces with strong Lewis acid/base functionality showed to be more efficient FXII activators than hydrophilic clean glass surfaces and hydrophobic octyl-sepharose particles. On the contrary, these ion-exchange surfaces showed to be inefficient plasma coagulation activators compared to clean glass, but slightly more efficient than octyl-sepharose. This phenomenon was caused by competitive protein-adsorption mechanics. Analysis indicated that blood plasma proteins hindered FXII contacting with activating surfaces by competing with FXII to adsorb the surface. However, any adsorbed FXIIa into the solution was quickly displaced and released into solution, which allowed the enzyme to initiate the plasma coagulation cascade (see Chapter 3 citations).