Fabrication of Avidin Single Molecular Layers on SiO2 Surfaces and Its Application to the Lipid Membrane Formation

Single molecular layers of avidin are fabricated on SiO2 surfaces, and characterized by atomic force microscopy (AFM) and infrared reflection absorption spectroscopy. Immobilization of avidin on the SiO2 surface is performed by; i) ester-group-modification of the surface using silane-coupling reagent, ii) carboxylation of the surface by hydrolyzation in HCl, and iii) amide bonding between the surface COOH and the-NH2 of the avidin. It is confirmed from the AFM observation that the immobilized avidin is dispersed and adsorbed as single molecules, not in aggregated state. Function-recognizing-AFM-observation shows that the binding ability of the avidin to biotin molecules is remained even after the covalent immobilization. Formation of tethered lipid bilayer membranes on the avidin single molecular layer bridged by avidin-biotin binding is also described.