Adsorption Behavior of DNA-Wrapped Carbon Nanotubes on Self-Assembled Monolayer Surfaces
Rebecca A. Zangmeister, James E. Maslar, A Opdahl, Michael J. Tarlov
We have examined the adsorption of DNA-wrapped single walled carbon nanotubes (DNA-SWNTs) on hydrophobic, hydrophilic, and charged surfaces of alkylthiol self-assembled monolayers (SAMs) on gold. Our goal is to understand how DNA-wrapped SWNTs interact with surfaces of varying chemical functionality. These samples were characterized using reflection absorption FTIR (RAIRS), X-ray photoelectron spectroscopy (XPS), and Raman spectroscopy. We have found that DNA-wrapped SWNTs preferentially adsorb to positively charged amine terminated SAMs and to bare gold surfaces versus hydrophobic methyl terminated or negatively charged carboxylic acid terminated SAMs. Examination of the adsorption on gold of single strand DNA (ssDNA) of the same sequence used to wrap the SWNTs indicate that the DNA wrapping plays a major roll in the deposition of DNA-SWNTs through either electrostatic interaction with positively charged SAMs or chemisorption to gold.