Sharp melting transitions in DNA hybrids without aggregate dissolution: Proof of neighboring-duplex cooperativity

Julianne M. Gibbs-Davis, George C. Schatz*, Son Binh T. Nguyen

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

54 Scopus citations


Similar to DNA-modified gold nanoparticles, comb polymer-DNA hybrids exhibit very sharp melting transitions that can be utilized in highly selective DNA detection systems. Current theories suggest that such sharp melting results from either a phase transition caused by the macroscopic dissolution of the aggregate or neighboring-duplex interactions in the close-packed environment between adjacent DNA duplexes. To delineate the contributions of each of these effects, an aggregate system based on polymer-DNA hybrids was designed to include both polymer-linked and partially untethered duplexes. When this hybridized system was subjected to thermal analysis, both types of duplexes exhibited sharp melting transitions. The very sharp melting transition displayed by the partially untethered DNA duplexes offers proof that neighboring-duplex interactions can indeed induce cooperativity. Contributions of this neighboring-duplex effect, as well as the enhanced stabilization observed in polymer-DNA:polymer-DNA aggregates, can be quantitatively assessed using a simple thermodynamic model. While neighboring-duplex interactions alone can lead to cooperative melting, the enhanced stabilization observed in polymer-DNA aggregates is a function of both neighboring-duplex interactions and multivalent or aggregate properties.

Original languageEnglish (US)
Pages (from-to)15535-15540
Number of pages6
JournalJournal of the American Chemical Society
Issue number50
StatePublished - Dec 19 2007

ASJC Scopus subject areas

  • General Chemistry
  • Biochemistry
  • Catalysis
  • Colloid and Surface Chemistry


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