Heterodimeric Protein Surface‐Coupling Platform: Immobilization of Conformation Switchable and Functional αIIbβ3 Integrin

Abstract Many biotechnologies require direct contact between biomolecules and (semi)solid substrates. However, little information is available regarding site‐directed covalent surface immobilization of heterodimeric proteins. Integrins are heterodimeric, conformationally dependent membrane adhesion‐receptors, which are important in the (patho)biology of almost all human diseases. In this study, a biomimetic‐platform is developed for covalent and site‐directed immobilization of oriented integrin heterodimers onto most hydroxyl bearing surfaces, herein demonstrated on both glass‐slides and silica‐particles. This platform consists of a self‐assembled monolayer, upon which C‐terminal modified αIIbβ3 integrin extracellular domains are oriented and covalently anchored. As with cell surface integrins, the conformation of immobilized αIIbβ3 is switchable and can be modulated to the active ligand‐binding conformation by divalent cations. Furthermore, the αIIbβ3‐coupled silica particles display platelet‐mimetic hemostat function and co‐aggregate with platelets from both wild‐type and fibrinogen/von Willebrand factor double deficient mice, facilitating αIIbβ3‐non‐classical ligand discoveries. This work provides a biomaterial platform for functional multimeric protein‐substrate coupling, which should have broad impact on multiple fields of biology, biotechnology, and clinical diagnosis/therapy.