Charging behavior of single-stranded DNA polyelectrolyte brushes

Gang Shen, Napoleon Tercero, Mariafrancis A. Gaspard, Bindhu Varughese, Kenneth Shepard, Rastislav Levicky

Research output: Contribution to journalArticle


DNA monolayers are widely used in fundamental and applied genomics and are versatile experimental models for elucidating the behavior of charged polymers at interfaces. The physical behavior of these systems is to a large extent governed by their internal ionic microenvironment, which is investigated here for layers of end-tethered, single-stranded DNA oligonucleotides (DNA brushes). Retention of counterions by the DNA brush manifests as lowered susceptibility of the interfacial capacitance to external salt conditions. A physical model based on concepts adapted from polymer science was used to further elucidate the connection between monolayer organization and its charging behavior. The data indicate a reorganization of the monolayer with changes in ionic strength and strand coverage that is consistent with that expected for a polyelectrolyte brush. A method for electrochemical quantification of strand coverage, based on shift of reduction potential for redox counterions associated with the DNA monolayer, is also described. These results provide guidance for development of label-free electrochemical diagnostics employing DNA monolayers and formulate a description of monolayer behavior within a polymer science framework.

Original languageEnglish (US)
Pages (from-to)8427-8433
Number of pages7
JournalJournal of the American Chemical Society
Issue number26
StatePublished - Jul 5 2006

ASJC Scopus subject areas

  • Catalysis
  • Chemistry(all)
  • Biochemistry
  • Colloid and Surface Chemistry

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