A DNA - Gold nanoparticle-based colorimetric competition assay for the detection of cysteine

Jae-Seung Lee, Pirmin A. Ulmann, Min Su Han, Chad A. Mirkin

Research output: Contribution to journalArticle

410 Citations (Scopus)


We report the development of a highly sensitive and selective colorimetric detection method for cysteine based upon oligonucleotide-functionalized gold nanoparticle probes that contain strategically placed thymidine-thymidine (T-T) mismatches complexed with Hg 2+. This assay relies upon the distance-dependent optical properties of gold nanoparticles, the sharp melting transition of oligonucleotide-linked nanoparticle aggregates, and the very selective coordination of Hg 2+ with cysteine. The concentration of cysteine can be determined by monitoring with the naked eye or a UV-vis spectrometer the temperature at which the purple-to-red color change associated with aggregate dissociation takes place. This assay does not utilize organic cosolvents, enzymatic reactions, light-sensitive dye molecules, lengthy protocols, or sophisticated instrumentation thereby overcoming some of the limitations of more conventional methods.

Original languageEnglish
Pages (from-to)529-533
Number of pages5
JournalNano Letters
Issue number2
Publication statusPublished - 2008 Feb 1
Externally publishedYes


ASJC Scopus subject areas

  • Materials Science(all)
  • Electronic, Optical and Magnetic Materials
  • Chemistry (miscellaneous)

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