Detection of unusual DNA structures with nanoparticles

Catherine Jones Murphy, Rahina Mahtab

Research output: Contribution to journalArticle


The generic global structure of the DNA double helix is well known, but at the base pair level there are a multitude of deviations from the 'ideal'. These deviations can result in sequence-directed curvature of DNA over a few base pairs. We have used luminescent mineral nanoparticles of CdS in optical assays to detect these curved DNAs. The nanoparticles, originally developed by the materials science community as 'quantum dots,' are approx. 20-100 angstrom in diameter, similar to proteins, and their photoluminescence is sensitive to the presence and nature of adsorbates. In this paper, we have investigated higher-order structures of nucleic acids that are correlated with human disease: triplet repeats of the single-stranded oligonucleotides 5′-(CCG)n-3′ and 5′-(CGG)n-3′. These sequences fold into structures that have not been determined, but give characteristic spectra in circular dichroism spectroscopy. Under salt conditions where 5′-(CCG)7-3′ and 5′-(CGG)7-3′ fold into these higher-order structures, our nanoparticles bind them well but do not bind to normal double-helical DNA. This result may form the basis for future assays of higher-order DNA structures.

Original languageEnglish (US)
Pages (from-to)10-16
Number of pages7
JournalProceedings of SPIE - The International Society for Optical Engineering
StatePublished - 2000
Externally publishedYes

ASJC Scopus subject areas

  • Electrical and Electronic Engineering
  • Condensed Matter Physics

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