Date of Award


Document Type


Degree Name

Master of Science in Applied Physics


Department of Engineering Physics

First Advisor

Larry W. Burggraf, PhD


The anthrax attack of Oct 2001 demonstrates the need for a rapid detector for spores of Bacillus anthracis (BA). Current technology requires cultures of BA to be grown for 24 hours. Using aptamers, a type of nucleic acid ligand selective for a target molecule, to select BA spores for measurement without culturing is a possible solution for quicker detection. An aptamer having a specially selected structure is expected to selectively bind to the surface of its target spore, separating it from other material. An atomic force microscopy (AFM) method was developed to test this selectivity. Aptamers having structure selected to recognize BA were attached to a silicon nitride AFM probe, which was put in contact with spores of Bacillus anthracis Sterne strain or B. thuringiensis var. kurstaki (BT). Using the AFM in contact mode, the adhesion force between the aptamer and the spores was measured. This research compared the difference in adhesion forces of a clean probe and a probe treated with these aptamers for both BA spores and BT spores to determine whether the enhanced selectivity of aptamers for BA compared with BT could be directly measured.

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