AVS 54th International Symposium | |
Biomaterial Interfaces | Thursday Sessions |
Session BI-ThP |
Session: | Biomaterial Interfaces Poster Session |
Presenter: | K. Wang, Polytechnic University |
Authors: | K. Wang, Polytechnic University M.A. Gaspar, Columbia University R.A. Zangmeister, National Institute of Standards and Technology R. Levicky, Polytechnic University |
Correspondent: | Click to Email |
Monolayers of immobilized nucleic acids (DNA) are promising experimental models for investigating fundamental properties of charged polymers at solid-liquid interfaces. We have investigated the charging behavior of single-stranded DNA polyelectrolyte brushes. In this study, voltammetric behavior of hexaamineruthenium(III) chloride (RuHex) in end-tethered single-stranded DNA monolayers of different strand lengths is investigated. The surface coverage of non-labeled DNA chains was determined independently with X-ray photoelectron spectroscopy (XPS). Our results show that, for DNA chains varying from 5 to 100 thymine nucleotides, the reduction potential of RuHex3+ counterions associated with the DNA monolayer is predominantly a function of chain surface coverage and is rather insensitive to the chain length. However, the total charge passed to reduce the counterions to the 2+ oxidation state is predominantly a function of the total nucleotide number, given by the product of chain surface coverage and chain degree of polymerization. A model is proposed to explain the observed behavior. The dynamic evolution of the reduction peak area and potential are also investigated, providing a picture of the time dependence of the adsorption of RuHex3+ into the monolayers. The research provides a method to estimate the chain coverage of non-labeled, end-tethered DNA chains with various chain lengths.