A surface plasmon resonance sensor array based upon a grating substrate was developed for the detection of biomolecular interactions. The substrate consisted of a gold grating prepared by wet chemical treatment of a commercial recordable compact disk. A custom-built floating pin microspotter was constructed to deliver solutions containing omega-functionalized linear alkanethiols to the grating surface and produce an array of sensor elements with different exposed functional end groups. This array platform can be used to study biomolecular interactions in a label-free, sensitive, and high-throughput format. To illustrate the performance of this device, a test protein (bovine serum albumin) was exposed to sensor elements containing an array of functionalized alkanethiols possessing either activated carboxylic acid-, amine-, or hydroxyl-terminated regions. Local changes in plasmon resonance were monitored in a fixed-angle imaging configuration. Plasmon images clearly distinguish the degree of protein attachment at the various surfaces. The molecular binding events on the grating were also confirmed by ellipsometry. This grating-based SPR imaging platform represents a simple and robust method for performing label-free, high-sensitivity, and high-throughput detection of biomolecular interactions.
"Two kinds of optical excitations can occur at metal/dielectric interfaces, propagating surface plasmons and localized ones, but the geometries of the excitations differ. Propagating surface plasmons are excited at flat metal/dielectric surfaces under total internal reflection of irradiated light or at grating metal/dielectric interfaces (Raether 1988), while localized surface plasmons are excited at metal-nanoparticle/dielectric interfaces (Willets and Van Duyne 2007). Both excitations are sensitive to material adsorption events, which change the dielectric constant on the metal surface. "
[Show abstract][Hide abstract] ABSTRACT: Grating-coupled propagating surface plasmons associated with silver-nanoparticle 2D crystalline sheets exhibit sensitive plasmonic resonance tuning. Multilayered silver-nanoparticle 2D crystalline sheets are fabricated on gold or silver grating surfaces by the Langmuir– Blodgett method. We show that the deposition of Ag crystalline nanosheets on Au or Ag grating surfaces causes a drastic change in propagating surface plasmon resonance (SPR) both in angle measurements at fixed wavelengths and in fixed incident-angle mode by irradiation of white light. The dielectric constant of the multilayered silver nanosheet is estimated by a rigorous coupled-wave analysis. We find that the dielectric constant drastically increases as the number of silver-nanosheet layers increases. The experimentally obtained SP dispersions of Ag crystalline nanosheets on Au and Ag gratings are compared with the calculated SP dispersion curves. The drastic change in the surface plasmon resonance caused by the deposition of Ag-nanoparticle 2D crystalline sheets on metal grating surfaces suggests the potential for applications in highly sensitive sensors or for plasmonic devices requiring greatly enhanced electric fields.
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"Although these techniques provide highly precise periodic structures and geometries on the nanoscale, they involve high cost and complexity in fabrication. Commercially available optical media on the other hand have drawn the attention of many researchers in the past few years as these offer an inexpensive alternative to fabrication of gratings  . CDs, DVDs and other optical disks have periodic gratings in the form of tracks on the polycarbonate substrate that can be coated with metal films to form plasmonic metal gratings   . "
[Show abstract][Hide abstract] ABSTRACT: We demonstrate strong electromagnetic field enhancement from nano-gaps embedded in silver gratings for visible wavelengths. These structures fabricated using a store-bought HD-DVD worth $10 and conventional micro-contact printing techniques have shown maximum fluorescence enhancement factors of up to 118 times when compared to a glass substrate under epi-fluorescent conditions. The novel fabrication procedure provides for the development of a cost-effective and facile plasmonic substrate for low-level chemical and biological detection. Electromagnetic field simulations were also performed that reveal the strong field confinement in the nano-gap region embedded in the silver grating, which is attributed to the combined effect of localized as well as propagating surface plasmons.
"One major advantage of using the grating-coupling excitation method is that a prism is not necessary. Hence, inexpensive and disposable plastics can be used as substrates, allowing for more flexible configurations     . In 2006, Zhang et al. reported a method for fabricating a periodic array of gold nanowire forms by spin-coating a colloidal gold suspension on indium tin oxide (ITO) grating structures, which were fabricated by interference lithography and functioned as a waveguide application. "
[Show abstract][Hide abstract] ABSTRACT: Imprinted solution-processible gold nanoparticle (AuNP) grating films were fabricated for use as a grating-coupled surface plasmon resonance (SPR) excitation substrate. The imprinted AuNP grating pattern, which consists of a 1.72 �m grating pitch, was fabricated on flat glass substrates by imprinting AuNP on silicon grating templates. In this study, the SPR measurements were carried out on an SPR device in the grating-coupling configuration with a He–Ne laser (� = 632.8 nm) as the excitation source, and multimode surface plasmon excitations were observed upon irradiation with white light. SPR excitation of our substrate was observed at the incident angle of 47.1◦. For SPR measurements using white light irradiation, multimode surface plasmon excitation resulting from several diffraction orders was observed in the wavelength region of 500–850 nm. The surface plasmon dispersion branches were calculated to obtain the diffraction order in this region. SPR excitation of the imprinted AuNP grating substrate was further studied by fabrication of a layer-by-layer ultrathin film of iron containing bis(terpyridine) polymer (Fe(II)-BTP) and poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS). A shift of the SPR excitation spectrum was observed when the ultrathin film was deposited on the imprinted AuNP grating surface. Thus, this substrate should be a useful SPR substrate in a variety of applications such as photoelectric conversions and sensors.
Sensors and Actuators B Chemical 07/2012; 173:316– 321. DOI:10.1016/j.snb.2012.07.003 · 4.10 Impact Factor
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