Molecular recognition reactions at interfaces as seen by fluorescence, plasmon surface polaritons and atomic force microscopy

• Published in: Thin solid films Vol. 210; pp. 666 - 669
• Main Authors: Schmitt, F.-J., Weisenhorn, A.L., Hansma, P.K., Knoll, W.
• Format: Journal Article
• Language: English
• Published: Elsevier B.V 30.04.1992
• ISSN: 0040-6090; 1879-2731
• DOI: 10.1016/0040-6090(92)90369-M

We investigated specific recognition reactions with various microscopic techniques. As a model for a receptor and its substrate we used biotin (vitamin H) [1] and streptavidin [2]. This well known system shows an extremely strong binding with a dissociation constant K = 1 × 10 −15 mol/1 and can be chemically modified in various ways [3], e.g. biotin can be covalently attached to a lipid [4]. In a binary mixture with a “non-reactive” lipid a phase transition leads to an enrichment of the biotin lipid in one phase. Microscopic techniques were applied to study the specific adsorption and binding of water soluble streptavidin to biotinylated interfaces. Microscopy offers certain advantages compared to integral measuring methods; especially when dealing with molecular events, lateral resolution yields more accurate data than spatially averaging methods. Parallel data recording and processing of different reaction sites are possible. The lateral phase separation leads to a reactive and a reference phase on the same sample. The applied techniques, thin film coatings and interfacial recognition reactions offer great potential for analytical applications such as biosensing.