Atomic force microscope for high resolution imaging and force spectrometry with chemical specificity

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Atomic force microscopy (AFM) is an imaging method whereby a sharp tip mounted on a cantilever is rastered over the surface of a sample.  As the tip travels over the sample, the adhesive or repulsive forces that it experiences will result in the deflection of the cantilever up and down.  This can be translated into a "map" of the surface the tip is traveling across, and thus into a three-dimensional topographic image of the sample.  The image resolution in AFM is much higher than a standard optical microscope, with features only 10 nanometers in size - i.e. some 50 times the size of an atom - being routinely resolved.  This grant is for the upgrade of an existing AFM system. The current AFM unit is about eight years old.  While the scanner and detector units remain in good condition, the electronic control modules and operating software are no longer state-of-the-art.  As we currently have two scanner units in operation, the new control module will allow us to run two AFM systems for the price of one, with the new system being dedicated to mapping of surface functional groups with high chemical specificity.  The new AFM system will be used by a group of five researchers within the chemistry department at Queen's University.  The upgraded system will allow us acquire high-resolution images of soft samples such as the surfaces of polymers, colloidal particles and of proteins or peptides that are grafted onto such surfaces.  In addition, the upgraded system will allow for imaging of the samples under water, which is particularly important in this case, as many of the chemical systems under study involve molecules immobilized on a solid surface in contact with water.  High resolution imaging of the materials under study is crucial in understanding their chemical reactivity as often adsorption of molecules critical to a reaction will only take place at unique, widely spaced sites on the surface.  The new equipment will allow us to characterize the materials used in novel separation and detection technologies, including the detection of trace quantities of heavy metals in environmental sensors; the detection and characterization of proteins and peptides in cheap, disposable medical devices; and the separation of drug molecules using chiral chromatography.