Agilent Attaching Antibodies to MAC Levers with the Bifunctional Amine-Amine Reactive PEG Tether - App Note free download

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Keysight Technologies Attaching Antibodies to MAC Levers with the Bifunctional Amine-Amine Reactive PEG Tether, Aldehyde-PEG18-NHS Application Note Introduction Biological molecules can be attached to silicon and silicon nitride AFM probes, transforming them into sensitive, nanoscale, biochemically selective sensors. The biochemically modified AFM probes can be used to study single molecule interactions in various AFM-based techniques. One such AFM-based method that relies on the biochemically modified AFM probes is a force spectroscopy (FS) technique called molecular recognition force microscopy (MRFM) [Riener 2003, Hinterdorfer 2004]. In MRFM, distinct interactions between even just one ligand molecule, which is immobilized on the tip of the AFM probe, and complimentary receptor molecules, which are immobilized on an opposing substrate, can be investigated one by one as the biochemically modified AFM probe first approaches and then is subsequently withdrawn away from the substrate. Unbinding interactions between the ligand and a receptor can be quantified because when the AFM probe is withdrawn away from the substrate, the molecular binding complex between the ligand and the receptor cause the AFM probe cantilever to bend. The bending of the cantilever can be monitored optically. It bends in relation to its inherent spring constant and the strength of the interaction between the ligand and the receptor. As the probe is withdrawn, the cantilever continues to bend until the ligand-receptor complex dissociates. Consequently, AFM-based force spectroscopy experiments can give valuable information about the structure and dynamics of molecular unbinding events at the single molecule level [Noy 1997] and to gain an understanding of the intramolecular forces involved in protein folding and polymer elongation [Allison 2002]. Another single molecule AFM technique that utilizes immobilized ligands on an AFM probe and receptor molecules immobilize on a substrate is topography-recognition imaging (TREC). TREC is a dynamic AFM technique in which an AFM probe, which contains Figure 1. Direct immobilization of ligands to the tip immobilized ligand molecules on its tip, oscillates in AC mode while it is scanned of an AFM probe. This type of immobilization can over a substrate which contains bound receptor molecules. A Keysight AFM that often lead to a high density of molecules on the is equipped with PicoTREC can resolve the molecular recognition signals from the probe, but these ligands are generally not able to diffuse within a defined volume of space nor are AFM surface topography signals so that the lateral positions of functionally active they able to reorient and bind with the receptors in receptors on