Streptavidin arrays as supramolecular architectures in surface-plasmon optical sensor formats

We describe a series of interfacial biomolecular architectures employed for studies aimed at elucidating the structural and dynamical factors governing biorecognition and binding reactions between surface-attached biotin-derivatives and analogues and streptavidin from solution. We compare binding matrices based on mixed lipid monolayers transferred to a solid support from the water/air-interface and surface coatings based on binary mixed self-assembled monolayers. The analytical techniques used to monitor the various layers and the binding events are based on surface-plasmon spectroscopy and microscopy, in some cases in combination with electrochemical methods controlling, in particular, the surface potential of electrode surfaces in contact with aqueous electrolyte solutions. Finally, an example is given for the sensitivity enhancement obtainable by combining the field-enhancement of surface-plasmon resonances with fluorescence detection schemes.