A new generation of sensors based on extraordinary optical transmission.

[Reaction: see text]. Plasmonic-based chemical sensing technologies play a key role in chemical, biochemical, and biomedical research, but basic research in this area is still attracting interest. Researchers would like to develop new types of plasmonic nanostructures that can improve the analytical figures of merit, such as detection limits, sensitivity, selectivity, and dynamic range, relative to the commercial systems. They are also tackling issues such as cost, reproducibility, and multiplexing with the goal of providing the best plasmonic-based platform for chemical analysis. In this Account, we will describe recent advances in the optical and spectroscopic properties of nanohole arrays in thin gold films and their applications for chemical sensing. These nanostructures support the unusual phenomenon of "extraordinary optical transmission" (EOT), that is, they are more transparent at certain wavelengths than expected by the classical aperture theory. The EOT is a consequence of surface plasmon (SP) excitations; hence, the resonance should respond to the adsorption of organic molecules. We explored this effect and implemented the integration of the arrays of nanoholes as sensing elements in a microfluidic architecture. We then demonstrated how these devices could be applied in biochemical affinity tests. Arrays of nanoholes offer a small sensing footprint and operate at normal transmission mode, which make them more suitable for miniaturization. This new approach for SPR sensing is more compatible with the lab-on-chip concept and offers the possibility of high-throughput analysis from a single sensing chip. We explored the field localization properties of EOT for surface-enhanced spectroscopy. We could control the enhancement factors for SERS and SEFS by adjusting the geometry of the arrays. The shape of the individual nanoholes offers another handle to tune the enhancement factor for surface-enhanced spectroscopy and SPR sensitivity. Apexes in shaped nanostructures function as optical antennas, focusing the light at extremely small regions at the tips. We observed additional surface enhancement by tuning the apexes' properties. The extra enhancement in these cases originated only from the small number of molecules in the apex regions. The arrays of nanoholes are an exciting new substrate for chemical sensing and enhanced spectroscopy. This class of nanomaterials has the potential to provide a viable alternative to the commercial SPR-based sensors. Further research could exploit this platform to develop nanostructures that support high field localization for single-molecule spectroscopy.

[1]  J. Homola.  Surface Plasmon Resonance Sensors for Detection of Chemical and Biological Species , 2008 .

[2]  J. V. Coe,et al.  Extraordinary transmission of metal films with arrays of subwavelength holes. , 2008, Annual review of physical chemistry.

[3]  Hyungsoon Im,et al.  Laser-illuminated nanohole arrays for multiplex plasmonic microarray sensing. , 2008, Optics express.

[4]  P. Stark,et al.  Breaking the diffraction barrier outside of the optical near-field with bright, collimated light from nanometric apertures , 2007, Proceedings of the National Academy of Sciences.

[5]  Reuven Gordon.  Bethe's aperture theory for arrays , 2007 .

[6]  N. Ming,et al.  Shape‐Selective Synthesis of Gold Nanoparticles with Controlled Sizes, Shapes, and Plasmon Resonances , 2007 .

[7]  Katherine E. Cilwa,et al.  Metal Films with Arrays of Tiny Holes: Spectroscopy with Infrared Plasmonic Scaffolding , 2007 .

[8]  N. Halas,et al.  Nano-optics from sensing to waveguiding , 2007 .

[9]  Chunlei Du,et al.  Localized surface plasmon nanolithography with ultrahigh resolution. , 2007, Optics express.

[10]  Way-Seen Wang,et al.  Sensitive biosensor array using surface plasmon resonance on metallic nanoslits. , 2007, Journal of biomedical optics.

[11]  Hyungsoon Im,et al.  Periodic nanohole arrays with shape-enhanced plasmon resonance as real-time biosensors , 2007 .

[12]  D. Sinton,et al.  On-chip surface-based detection with nanohole arrays. , 2007, Analytical chemistry.

[13]  R. V. Van Duyne,et al.  Localized surface plasmon resonance spectroscopy and sensing. , 2007, Annual review of physical chemistry.

[14]  Thomas H. Reilly,et al.  Quantitative evaluation of plasmon enhanced Raman scattering from nanoaperture arrays , 2007 .

[15]  Diego Krapf,et al.  Mesoscopic concentration fluctuations in a fluidic nanocavity detected by redox cycling. , 2007, Nano letters.

[16]  Borja Sepúlveda,et al.  Nanohole plasmons in optically thin gold films , 2007 .

[17]  Alexandre G. Brolo,et al.  Apex-Enhanced Raman Spectroscopy Using Double-Hole Arrays in a Gold Film , 2007 .

[18]  R. Gordon,et al.  Apex-enhanced second-harmonic generation by using double-hole arrays in a gold film , 2007 .

[19]  T. Ebbesen,et al.  Light in tiny holes , 2007, Nature.

[20]  Qian-jin Wang,et al.  Dual effect of surface plasmons in light transmission through perforated metal films , 2006, physics/0612023.

[21]  J. V. Coe,et al.  Extraordinary infrared transmission of a stack of two metal micromeshes , 2007 .

[22]  A. Kumar,et al.  Microlens array fabrication by laser interference lithography for super-resolution surface nanopatterning , 2006 .

[23]  T. Ebbesen,et al.  Raman scattering and fluorescence emission in a single nanoaperture: Optimizing the local intensity enhancement , 2006 .

[24]  D. Qiu,et al.  Hole-Enhanced Raman Scattering , 2006, Applied spectroscopy.

[25]  Teri W Odom,et al.  Direct evidence for surface plasmon-mediated enhanced light transmission through metallic nanohole arrays. , 2006, Nano letters.

[26]  Jing Zhao,et al.  Localized Surface Plasmon Resonance Biosensing with Large Area of Gold Nanoholes Fabricated by Nanosphere Lithography , 2010, Nanoscale research letters.

[27]  Y. Fainman,et al.  High-resolution surface plasmon resonance sensor based on linewidth-optimized nanohole array transmittance. , 2006, Optics letters.

[28]  M. D. Cooper,et al.  Surface plasmon-quantum dot coupling from arrays of nanoholes. , 2006, The journal of physical chemistry. B.

[29]  J. Lakowicz.  Plasmonics in Biology and Plasmon-Controlled Fluorescence , 2006, Plasmonics.

[30]  E. Ozbay.  Plasmonics: Merging Photonics and Electronics at Nanoscale Dimensions , 2006, Science.

[31]  R. Aroca,et al.  Surface enhanced vibrational spectroscopy , 2006 .

[32]  Jason Riordon,et al.  Enhanced fluorescence from arrays of nanoholes in a gold film. , 2005, Journal of the American Chemical Society.

[33]  P. Stark,et al.  Short order nanohole arrays in metals for highly sensitive probing of local indices of refraction as the basis for a highly multiplexed biosensor technology. , 2005, Methods.

[34]  Stefan Enoch,et al.  Role of shape and localized resonances in extraordinary transmission through periodic arrays of subwavelength holes: Experiment and theory , 2005 .

[35]  K. Kavanagh,et al.  Basis and lattice polarization mechanisms for light transmission through nanohole arrays in a metal film. , 2005, Nano letters.

[36]  N. Fang,et al.  Sub–Diffraction-Limited Optical Imaging with a Silver Superlens , 2005, Science.

[37]  Chad A Mirkin,et al.  Nanostructures in biodiagnostics. , 2005, Chemical reviews.

[38]  Reuven Gordon,et al.  Increased cut-off wavelength for a subwavelength hole in a real metal. , 2005, Optics express.

[39]  G. Whitesides,et al.  New approaches to nanofabrication: molding, printing, and other techniques. , 2005, Chemical reviews.

[40]  Thomas W. Ebbesen,et al.  The role of localized surface plasmon modes in the enhanced transmission of periodic subwavelength apertures , 2005 .

[41]  Alexandre G. Brolo,et al.  Nanohole-Enhanced Raman Scattering , 2004 .

[42]  Thomas W. Ebbesen,et al.  Optical transmission properties of a single subwavelength aperture in a real metal , 2004 .

[43]  Henri Lezec,et al.  Diffracted evanescent wave model for enhanced and suppressed optical transmission through subwavelength hole arrays. , 2004, Optics express.

[44]  Y. Liu,et al.  Biosensing based upon molecular confinement in metallic nanocavity arrays , 2004, Digest of the LEOS Summer Topical Meetings Biophotonics/Optical Interconnects and VLSI Photonics/WBM Microcavities, 2004..

[45]  K. Kavanagh,et al.  Surface plasmon sensor based on the enhanced light transmission through arrays of nanoholes in gold films. , 2004, Langmuir : the ACS journal of surfaces and colloids.

[46]  N. V. van Hulst,et al.  Strong influence of hole shape on extraordinary transmission through periodic arrays of subwavelength holes. , 2004, Physical review letters.

[47]  K. Kavanagh,et al.  Strong polarization in the optical transmission through elliptical nanohole arrays. , 2004, Physical review letters.

[48]  J. P. Woerdman,et al.  Fano-type interpretation of red shifts and red tails in hole array transmission spectra , 2003, physics/0401054.

[49]  W. Barnes,et al.  Surface plasmon subwavelength optics , 2003, Nature.

[50]  Younan Xia,et al.  Gold and silver nanoparticles: a class of chromophores with colors tunable in the range from 400 to 750 nm. , 2003, The Analyst.

[51]  R A Linke,et al.  Beaming Light from a Subwavelength Aperture , 2002, Science.

[52]  Piers Andrew,et al.  Molecular fluorescence above metallic gratings , 2001 .

[53]  R. Wannemacher.  Plasmon-supported transmission of light through nanometric holes in metallic thin films , 2001 .

[54]  S. Blair,et al.  Resonant-enhanced evanescent-wave fluorescence biosensing with cylindrical optical cavities. , 2001, Applied optics.

[55]  H. Lezec,et al.  Extraordinary optical transmission through sub-wavelength hole arrays , 1998, Nature.

[56]  Leigh B. Bangs,et al.  New developments in particle-based immunoassays: Introduction , 1996 .

[57]  Thomas K. Gaylord,et al.  Rigorous coupled-wave analysis of metallic surface-relief gratings , 1986 .

[58]  H. Bethe.  Theory of Diffraction by Small Holes , 1944 .