麻省理工学院 生物材料课程 Lecture 9 Surface Modification of Biomaterials.pdfVIP

3.051J/20.340J 1 Lecture 9: Surface Modification of Biomaterials Purpose: alter surface properties to enhance performance in biological environment while retaining bulk properties of device Specific Objectives: 1. clean a surface 2. reduce/eliminate protein adsorption • reduce undesirable/uncontrolled responses to implants extracorpeal devices C3b/IgG adsorption ⇒activation of WBCs • reduce nonspecific adsorption on biosensors bioassays (noise fouling) Source: Wikipedia (Grays Anatomy) • current strategy: hydrated, hydrophilic surfaces PEO is current “gold standard” 3. reduce/eliminate cell adhesion • create surfaces that mimic nature’s cell resistant surfaces ex. Human serum albumin: naturally low affinity to components of body fluids tissues (consider its high conc. in blood—60 wt% of proteins!) 3.051J/20.340J 2 4. reduce thromogenicity •hydrophilic surfaces - eliminate protein adsorption •hydrophobic surfaces - inherently weak surface/cell interface - exploits shear stress due to blood flow •surface-bound heparin - natural surface of endothelial cells lining blood vessels - inactivates factor Xa thrombin by binding anti-thrombin •surface-bound albumin - no ligands for platelets (can attach if HSA denatures-how?) •albumin affinity coatings - surfaces that strongly adsorb albumin from blood to make a passive coating; ex. bilirubin Kd ~ 10-8 l/mol •endothelial cell attachment - natural blood vessel lining ⇒ fibrin