Atomic force microscopy (AFM) is a well known member of the so called SXM family. The entire SXM technology is based on the invention of scanning tunneling microscopy (STM). In all these types of instruments a sharp probe interacting locally with the specimen, is scanned by a piezoelectric scanner providing three-dimensional information about the surface. "Beyond topography" is a new SPM (scanning probe microcopy) field, which exploits the ability of these instruments to measure minimal forces in high accuracy, in order to provide additional information about the scanned object.
In this work we present a novel AFM method, which leads to recognition of specific biological molecules like: proteins, DNA strands and even receptor sites over a whole biological cell. The goal of our method is to combine between high resolution topography image and the force detection map of the scanned object (Imaging with the sensitivity of a pN scale). Biological ligands such as antibodies or drugs are attached to the AFM tip. When a recognition event between the ligand and the target occurs, the AFM detects the minute forces which are required to break the interactions, which are involved in molecular binding. This technique is useful to measure binding forces between antibodies-antigens, drugs-hormones, receptors-ligands and between protein-DNA complexes.
The outcome of this technique is an image which provides the topography of the scanned surface, and an image which displays a map of binding interactions between the ligands (on the AFM tip) and the target molecules on the surface. By merging these two images, we get a new Image ("recognition Image"), which demonstrates the location of all the target molecules (by their coordinates) over the scanned sample.
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