Quantitative Characterization of DNA Films by X-ray Photoelectron Spectroscopy
MARYLAND UNIV COLLEGE PARK DEPT OF PHYSICS
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We describe the use of self-assembled films of thiolated dT25 single-stranded DNA ssDNA on gold as a model system for quantitative characterization of DNA films by X-ray photoelectron spectroscopy XPS. We evaluate the applicability of a uniform and homogeneous overlayer-substrate model for data analysis, examine model parameters used to describe DNA films e.g., density and electron attenuation length, and validate the results. The model is used to obtain quantitative composition and coverage information as a function of immobilization time. We find that when the electron attenuation effects are properly included in theXPSdata analysis, excellent agreement is obtained with Fourier transform infrared FTIR measurements for relative values of the DNA coverage, and the calculated absolute coverage is consistent with a previous radiolabeling study. Based on the effectiveness of the analysis procedure for model dT25 ssDNA films, it should be generally valid for direct quantitative comparison of DNA films prepared under widely varying conditions.
- Atomic and Molecular Physics and Spectroscopy