Plasmonic amplification for bioassays with epi-fluorescence readout.

Corrugated metallic surfaces offer means for efficient amplification of fluorescence bioassay signal based on the near field coupling between surface plasmons and fluorophore emitters that are used as labels. This paper discusses the design of such plasmonic structure to enhance the sensitivity of immunoassays with epi-fluorescence readout geometry. In particular, crossed gold grating is theoretically and experimentally investigated for combined increasing of the excitation rate at the fluorophore excitation wavelength and utilizing directional surface plasmon-coupled fluorescence emission. For Alexa Fluor 647 dye, the enhancement factor of around EF = 102 was simulated and experimentally measured. When applied to a sandwich interleukin-6 immunoassay, highly surface-selective enhancement reaching a similar value was observed. Besides increasing the measured fluorescence signal associated with the molecular binding events on a surface by two orders of magnitude, the presented approach enables measuring kinetics of the surface reaction that is otherwise masked by strong background signal originating from bulk solution.

[1]  I. Kumagai,et al.  Zinc oxide-coated plasmonic chip modified with a bispecific antibody for sensitive detection of a fluorescent labeled-antigen. , 2011, Analytical chemistry.

[2]  J. Nishii,et al.  Sensitive bioimaging in microfluidic channels on the plasmonic substrate: Application of an enhanced fluorescence based on the reverse coupling mode , 2011 .

[3]  W. Knoll,et al.  Emission of light from Ag metal gratings coated with dye monolayer assemblies , 1981 .

[4]  Gang-yu Liu,et al.  A nanoengineering approach for investigation and regulation of protein immobilization. , 2008, ACS nano.

[5]  Wolfgang Knoll,et al.  Surface-Plasmon Field-Enhanced Fluorescence Spectroscopy , 2000 .

[6]  J. Lakowicz,et al.  Plasmon-controlled fluorescence: a new paradigm in fluorescence spectroscopy. , 2008, The Analyst.

[7]  G. W. Ford,et al.  Electromagnetic interactions of molecules with metal surfaces , 1984 .

[8]  Milan Vala,et al.  Compact surface plasmon-enhanced fluorescence biochip. , 2013, Optics express.

[9]  Jiří Homola,et al.  Surface plasmon-coupled emission on plasmonic Bragg gratings. , 2012, Optics express.

[10]  Zygmunt Gryczynski,et al.  Directional surface plasmon-coupled emission: A new method for high sensitivity detection. , 2003, Biochemical and biophysical research communications.

[11]  R. W. Christy,et al.  Optical Constants of the Noble Metals , 1972 .

[12]  Lukas Novotny,et al.  Spectral dependence of single molecule fluorescence enhancement. , 2007, Optics express.

[13]  W H Weber,et al.  Energy transfer from an excited dye molecule to the surface plasmons of an adjacent metal. , 1979, Optics letters.

[14]  J. Attridge,et al.  Sensitivity enhancement of optical immunosensors by the use of a surface plasmon resonance fluoroimmunoassay. , 1991, Biosensors & bioelectronics.

[15]  F. J. Wolf,et al.  THE PROPERTIES OF STREPTAVIDIN, A BIOTIN-BINDING PROTEIN PRODUCED BY STREPTOMYCETES. , 1964, Archives of biochemistry and biophysics.

[16]  B. MacCraith,et al.  Surface plasmon-coupled emission (SPCE)-based immunoassay using a novel paraboloid array biochip. , 2010, Biosensors & bioelectronics.

[17]  William L. Barnes,et al.  Photoluminescence from dye molecules on silver gratings , 1996 .

[18]  Collective localized surface plasmons for high performance fluorescence biosensing. , 2013, Optics express.

[19]  Wolfgang Knoll,et al.  Biosensors based on surface plasmon-enhanced fluorescence spectroscopy (Review) , 2008, Biointerphases.

[20]  J. Nishii,et al.  Enhanced Fluorescence Microscopic Imaging by Plasmonic Nanostructures: From a 1D Grating to a 2D Nanohole Array , 2010 .

[21]  P. Tinnefeld,et al.  Breaking the concentration limit of optical single-molecule detection. , 2014, Chemical Society reviews.

[22]  Jakub Dostalek,et al.  Plasmon-Enhanced Fluorescence Biosensors: a Review , 2013, Plasmonics.