Conference of the NATO-Advanced-Study-Institute on Nanoengineered Nanofibrous Materials, Belek-Antalya, Turkey, 1 - 12 September 2003, vol.169, pp.377-384, (Full Text)
Model single strand DNA (ssDNA) was covalently immobilized onto Atomic Force Microscope (AFM) tips (cantilevers) as specific ligand. Then these tips were interacted with the buffer solutions with or without free ssDNA molecules as strand were used for comparison. Immobilization and hybridization onto the cantilever surfaces were observed by optical and fluorescence microscopies. Interactions between the AFM cantilever (tip) and the aqueous medium (therefore with the target ssDNAs) were quantified by obtaining the "percent descenting distance" ("PDD") as the main variable. The PDD values obtained for the buffer solutions were between -2.07 and +4.91%. There were slight increases in the negative values when a non-complementary ssDNA molecules were introduce into the buffer. However, after hybridization with its complemenray ssDNA, the PDD values were significantly increased (between -32.24 and -43.47 %). There was a correlation between the concentration of the complementary target ssDNA in the medium and the PDD value. However, there were significant changes from one AFM cantilever to another, which was considered as a problem to be solved. However, it was concluded that this approach may be further develop to create AFM based molecular sensors.