title: Leaky-mode assisted fluorescence extraction: application to fluorescence enhancement biosensors.
abstract: Efficient recovery of light emitted by fluorescent molecules by employing photonic structures can result in high signal-to-noise ratio detection for biological applications including DNA microarrays, fluorescence microscopy and single molecule detection. By employing a model system comprised of colloidal quantum dots, we consider the physical basis of the extraction effect as provided by photonic crystals. Devices with different lattice symmetry are fabricated ensuring spectral and spatial coupling of quantum dot emission with leaky eigenmodes and the emission characteristics are studied using angle-resolved and angle-integrated measurements. Comparison with numerical calculations and lifetime measurements reveals that the enhancement occurs via resonant redirection of the emitted radiation. Comparison of various lattices reveals differences in the enhancement factor with a maximum enhancement factor approaching 220. We also demonstrate the first enhanced extraction biosensor that allows for over 20-fold enhancement of the fluorescence signal in detection of the cytokine TNF-alpha by a fluorescence sandwich immunoassay.
authors.affiliation: 1Department of Electrical and Computer Engineering, Nano Sensors Group, University of Illinois at Urbana-Champaign, 208 North Wright Street, Urbana, Illinois 61801, USA.
authors.forename: Nikhil
authors.initials: N
authors.lastname: Ganesh
authors.forename: Ian D
authors.initials: ID
authors.lastname: Block
authors.forename: Patrick C
authors.initials: PC
authors.lastname: Mathias
authors.forename: Wei
authors.initials: W
authors.lastname: Zhang
authors.forename: Edmond
authors.initials: E
authors.lastname: Chow
authors.forename: Viktor
authors.initials: V
authors.lastname: Malyarchuk
authors.forename: Brian T
authors.initials: BT
authors.lastname: Cunningham
mesh_terms: D000818:Animals; D015374:Biosensing Techniques; D001330:Electronic Data Processing; D004867:Equipment Design; D005453:Fluorescence; D005456:Fluorescent Dyes / Q000737:chemistry; D007124:Immunoenzyme Techniques; D018625:Microscopy, Atomic Force; D008962:Models, Theoretical; D020411:Oligonucleotide Array Sequence Analysis; D055095:Optics and Photonics; D045663:Quantum Dots; D013050:Spectrometry, Fluorescence / Q000379:methods*; D014409:Tumor Necrosis Factor-alpha / Q000378:metabolism
chemical_list: D005456:Fluorescent Dyes; D014409:Tumor Necrosis Factor-alpha