title: Distance-mediated plasmonic dimers for reusable colorimetric switches: a measurable peak shift of more than 60 nm.
abstract: The first reconfigurable colorimetric DNA switches based on target DNA binding are reported. This DNA binding actuates a change in the interparticle distance between gold nanoparticle dimers. A significant spectral shift of 68 nm is achievable from on-off switching. The reconfigurability is possible owing to thiol and EDC-imidazole coupling which anchors the DNA linkers to the nanoparticles. The huge spectral shift allows the unaided eye to observe single target biomolecular binding event in real time under a darkfield microscope. The limit-of-detection for target molecules in PBS and human serum are 10(-13)  M and 10(-11)  M respectively. An improved fabrication strategy via asymmetric functionalization is also described, assisted by solid phase synthesis which minimizes the formation of trimers and multimers.
authors.affiliation: Division of Bioengineering, School of Chemical and Biomedical Engineering, Nanyang Technological University, Singapore.
authors.forename: Longhua
authors.initials: L
authors.lastname: Guo
authors.forename: Abdul Rahim
authors.initials: AR
authors.lastname: Ferhan
authors.forename: Hailan
authors.initials: H
authors.lastname: Chen
authors.forename: Changming
authors.initials: C
authors.lastname: Li
authors.forename: Guonan
authors.initials: G
authors.lastname: Chen
authors.forename: Seungpyo
authors.initials: S
authors.lastname: Hong
authors.forename: Dong-Hwan
authors.initials: DH
authors.lastname: Kim
mesh_terms: D003124:Colorimetry / Q000379:methods*; D004247:DNA / Q000737:chemistry*; D019281:Dimerization; D008855:Microscopy, Electron, Scanning
chemical_list: D004247:DNA