DNA Probed by Second Harmonic GenerationPublic Deposited
Second harmonic generation (SHG), a nonlinear optical tool, was used to characterize DNA bound through a chemical linker to the flat surface of a hemispherical lens. Contact angle measurements were used to guarantee that the chemical linker did not hydrolyze under experimental conditions. SHG experiments followed the effects of salt concentration in the aqueous phase above the lens, which provided a standard curve used in calculating thermodynamic parameters of DNA hybridization and melting. Other SHG experiments tested the polar response of the surface using different input and output polarizations. Probing the surfaces with different combinations of polarizations served as a survey for determining the dynamic range of signals between single- and double-stranded DNA. The results from this investigation will be used as controls in further DNA characterization experiments to optimize current DNA detection methods.