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One of the hallmarks of Alzheimer's disease (AD) is the aggregation of amyloid beta (Aß) peptides into plaques causing loss of memory and neuronal death. Currently, there are two prevailing theories about the mechanisms of plaque formation. One mechanism assumes that fibril formation begins with oligomers (binding of three or more monomeric species of Aß peptides). The deposition of individual oligomers then promotes fibrillar growth. In the second, the fibrils are formed directly from circulating monomers. In both cases, it is also recognized that the plaques are formed of Aß with both 1-40 and 1-42 amino acid sequences. However, the mechanisms of action and aggregation of the plaques are not well understood, and it is believed that knowledge of these mechanisms can help understand plaque dissolution. We have used two powerful and independent techniques to discern the mechanisms of formation that fibrillar and oligomeric species undergo. One technique is attenuated total reflection Fourier transform infrared (ATR-FTIR) spectroscopy, which monitors the time evolution of the secondary structure of the Aß peptides when they undergo conformational changes. We have been able to detect changes in parallel and anti-parallel ß-sheets, beta turns, random coils, and αλπηα-helix structures. We have also used Atomic Force Microscopy (AFM) to determine the topology associated with the evolution of fibrillar formation. We have tested systems consisting of Aß1-40 and Aß1-42 separately, and a 1:1 molar-mix of Aß1-40/Aß1-42. We have been able to correlate the chemical conformation structures from the ATR-FTIR to the topographic nanostructure from the AFM. These measurements have determined that monomeric species of Aß1-40 and Aß1-42 peptides have predominantly anti-parallel ß-sheet structures. Fibrillar species, on the other hand, show predominantly parallel ß-sheet configurations. The oligomeric structures have a higher amount of parallel ß-sheets and show a competing kinetic growth with the αλπηα-helix structures. When Aß1-40 fibrils are incubated separately, they show a slower kinetic action of fibril formation than that of Aß1-42 fibrils or fibrils from the combined mix. When fibril formation begins, a slightly higher amount of αλπηα-helix structures is observed, which seems to indicate that they play a role in fibrillar growth.