Single molecule interactions between biotin and streptavidin were characterized with functionalized DeepTipTM probes and used as a model system to develop a comprehensive methodology for the high-yield identification and analysis of single molecular events. The procedure comprises the covalent binding of the target molecule to a surface and of the sensing molecule to the DeepTipTM probe, so that the interaction between both chemical species can be characterized by obtaining force-displacement curves in an atomic force microscope. It is shown that molecular resolution is consistently attained with a percentage of successful events higher than 90% of the total number of recorded curves, and a very low level of unspecific interactions. The combination of both features is a clear indication of the robustness and versatility of the proposed methodology.
Keywords: AFM; affinity atomic force microscopy; biotin; functionalization; streptavidin.