title: Plasmonic split-ring resonators as dichroic nanophotonic DNA biosensors.
abstract: Surface enhanced resonance Raman spectroscopy (SERRS) is a powerful molecular sensing tool that can be applied to a number of applications in the field of molecular diagnostics. We demonstrate that by using electron beam lithography to manipulate the nanoscale geometry of Ag split-ring resonators we can tune their optical properties such that they exhibit two independently addressable high frequency plasmon resonance modes for SERRS. This tailored multimodal, polarization dependent activity enables the split rings to act as discriminating sensors, with each resonance tuned for a particular sensing purpose. The structures are used as multiwavelength, multianalyte DNA SERRS sensors, with each resonance tuned to both the absorption wavelength of a differently colored Raman reporter molecule and its corresponding laser excitation wavelength. The ability of each resonance to independently sense small concentrations of a single DNA type from within a mixed population is demonstrated. Also shown is the effect of the split ring's dichroic response on the SERRS signal and the sensor's limit of detection of each resonance mode (switching its sensory reaction "on" and "off" depending on the orientation of the exciting light).
authors.affiliation: Department of Electronics and Electrical Engineering, University of Glasgow, Rankine Building, Oakfield Avenue, Glasgow, UK, G12 8LT. aclark@elec.gla.ac.uk
authors.forename: Alasdair W
authors.initials: AW
authors.lastname: Clark
authors.forename: Andrew
authors.initials: A
authors.lastname: Glidle
authors.forename: David R S
authors.initials: DR
authors.lastname: Cumming
authors.forename: Jonathan M
authors.initials: JM
authors.lastname: Cooper
mesh_terms: D001483:Base Sequence; D015374:Biosensing Techniques / Q000379:methods*; D004247:DNA / Q000032:analysis* / Q000235:genetics; D036103:Nanotechnology; D055620:Optical Phenomena; D013059:Spectrum Analysis, Raman
chemical_list: D004247:DNA