A conformation- and ion-sensitive plasmonic biosensor

W. Paige Hall, Justin Modica, Jeffrey Anker, Yao Lin, Milan Mrksich, Richard P. Van Duyne

Research output: Contribution to journalArticlepeer-review

107 Scopus citations


The versatile optical and biological properties of a localized surface plasmon resonance (LSPR) sensor that responds to protein conformational changes are illustrated. The sensor detects conformational changes in a surface-bound construct of the calcium-sensitive protein calmodulin. Increases in calcium concentration induce a 0.96 nm red shift in the spectral position of the LSPR extinction maximum (λmax). Addition of a calcium chelating agent forces the protein to return to its original conformation and is detected as a reversal of the λmax shift. As opposed to previous work, this work demonstrates that these conformational changes produce a detectable shift in λmax even in the absence of a protein label, with a signal:noise ratio near 500. In addition, the protein conformational changes reversibly switch both the wavelength and intensity of the resonance peak, representing an example of a bimodal plasmonic component that simultaneously relays two distinct forms of optical information. This highly versatile plasmonic device acts as a biological sensor, enabling the detection of calcium ions with a biologically relevant limit of detection of 23 μM, as well as the detection of calmodulin-specific protein ligands.

Original languageEnglish (US)
Pages (from-to)1098-1105
Number of pages8
JournalNano letters
Issue number3
StatePublished - Mar 9 2011


  • Nanoparticle
  • calcium detection
  • conformational change
  • ion sensor
  • localized surface plasmon resonance

ASJC Scopus subject areas

  • Condensed Matter Physics
  • Mechanical Engineering
  • Bioengineering
  • Chemistry(all)
  • Materials Science(all)


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