Article

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

ABSTRACT

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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    • "In order to delegate some of responsibilities to equipments/instruments in sensing humans developed sensor. Sensors are the devices which can reacts to a perceptible action, such as heat, light, or pressure [1]. Sensor then responds to that action by generating a signal that can be deduced. "
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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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    ABSTRACT: The effect of DNA–DNA interaction on the localized surface plasmon resonance of single 80 nm gold nanoparticles is studied. Therefore, both the attachment of the capture DNA strands at the particle surface and the sequence-specific DNA bind-ing (hybridization) of analyte DNA to the immobilized capture DNA is subject of investigations. The influ-ence of substrate attachment chemistry, the packing density of DNA as controlled by an assisting layer of smaller molecules, and the distance as increased by a linker on the LSPR efficiency is investigated. The resulting changes in signal can be related to a higher hybridization efficiency of the analyte DNA to the immobilized capture DNA. The subsequent attach-ment of additional DNA strands to this system is studied, which allows for a multiple step detection of binding and an elucidation of the resulting resonance shifts. The detection limit was determined for the utilized DNA system by incubation with various concentration of analyte DNA. Although the method allows for a marker-free detection, we show that additional markers such as 20 nm gold particle labels increase the signal and thereby the sensitivity signif-icantly. The study of resonance shift for various DNA lengths revealed that the resonance shift per base is stronger for shorter DNA molecules (20 bases) as compared to longer ones (46 bases).
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