High-resolution biosensor based on localized surface plasmons

Institute of Photonics and Electronics, Academy of Sciences of the Czech Republic, Chaberská 57, Prague, Czech Republic.
Optics Express (Impact Factor: 3.49). 01/2012; 20(1):672-80. DOI: 10.1364/OE.20.000672
Source: PubMed


We report on a new biosensor with localized surface plasmons (LSP) based on an array of gold nanorods and the total internal reflection imaging in polarization contrast. The sensitivity of the new biosensor is characterized and a model detection of DNA hybridization is carried out. The results are compared with a reference experiment using a conventional high-resolution surface plasmon resonance (SPR) biosensor. We show that the LSP-based biosensor delivers the same performance as the SPR system while involving significantly lower surface densities of interacting molecules. We demonstrate a limit of detection of 100 pM and a surface density resolution of only 35 fg×mm-2 that corresponds to less than one DNA molecule per nanoparticle on average.

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Available from: Hana Sípová, Aug 18, 2014
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    • "The propagation constant of the SPs is highly sensitive to changes in the relative electric permittivity, or equivalently, the refractive index of dielectric. The SPR biosensor is known as a very effective optical detection for absorption of biomolecules [6]. This is due to the great change in the excitation angle of SPs which made by local variation of refractive index in sensing medium near the sensor surface. "
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    • "Also the usage of single-and double-stranded DNA molecules as molecular ruler between two nanoparticles has been shown, concurrently being the first experiment where a DNA hybridization step has been demonstrated on a single particle level (Sönnichsen et al. 2005a). LSPR sensing with a limit of detection of 100 pM with an average density of less than one DNA molecule per involved gold nanostructures has been demonstrated (Piliarik et al. 2012). A parallel approach with an array consisting of hundreds of nanoparticles has shown a femtomolar detection limit for DNA hybridization events (Verdoold et al. 2011). "
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    • "LSPRs are collective oscillations of conducting electrons in the nanoparticles, and they give rise to strongly enhanced and highly localized electromagnetic fields polarized perpendicularly to the metal surfaces. Compared to SPPs, LSPRs are much more localized and allow probing processes at the interface with spatial sensitivities on the nanometre scale [5] [6] [7]. LSPRs have been widely used in various sensing devices due to their high sensitivity to the refractive index of the surroundings [6] [7] [8] [9], as well as for enhancing Raman [10] [11], fluorescence [12] [13] [14] [15], IR [16] or second harmonic [17] signals. "
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