A conformation- and ion-sensitive plasmonic biosensor.

ABSTRACT: 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 (?(max)). Addition of a calcium chelating agent forces the protein to return to its original conformation and is detected as a reversal of the ?(max) shift. As opposed to previous work, this work demonstrates that these conformational changes produce a detectable shift in ?(max) 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 ?M, as well as the detection of calmodulin-specific protein ligands.

SUBMITTER: Hall WP 

PROVIDER: S-EPMC3122133 | biostudies-literature | 2011 Mar

REPOSITORIES: biostudies-literature