Article

Multiple Label-Free Detection of Antigen−Antibody Reaction Using Localized Surface Plasmon Resonance-Based Core−Shell Structured Nanoparticle Layer Nanochip

Faculty of Engineering, Okayama University of Science, Okayama, Okayama, Japan
Analytical Chemistry (Impact Factor: 5.64). 10/2006; 78(18):6465-75. DOI: 10.1021/ac0608321
Source: PubMed

ABSTRACT

In this research, a localized surface plasmon resonance (LSPR)-based bioanalysis method for developing multiarray optical nanochip suitable for screening bimolecular interactions is described. LSPR-based label-free monitoring enables to solve the problems of conventional methods that require large sample volumes and time-consuming labeling procedures. We developed a multiarray LSPR-based nanochip for the label-free detection of proteins. The multiarray format was constructed by a core-shell-structured nanoparticle layer, which provided 300 nanospots on the sensing surface. Antibodies were immobilized onto the nanospots using their interaction with Protein A. The concentrations of antigens were determined from the peak absorption intensity of the LSPR spectra. We demonstrated the capability of the array measurement using immunoglobulins (IgA, IgD, IgG, IgM), C-reactive protein, and fibrinogen. The detection limit of our label-free method was 100 pg/mL. Our nanochip is readily transferable to monitor the interactions of other biomolecules, such as whole cells or receptors, with a massively parallel detection capability in a highly miniaturized package. We anticipate that the direct label-free optical immunoassay of proteins reported here will revolutionize clinical diagnosis and accelerate the development of hand-held and user-friendly point-of-care devices.

Download full-text

Full-text

Available from: Naoki Nagatani, Apr 25, 2014
    • "For point-of-care (POC) devices, dye-doped silica NPs are attracting significant attention and have already been integrated into commercial products [12] [13] [14] [15]. With a large amount of dye encapsulation, the increased brightness of these NPs results in improved signal-to-noise ratios compared "
    [Show abstract] [Hide abstract]
    ABSTRACT: This paper describes the fabrication of oligonucleotide-coated Cy5-doped silica nanoparticles using a combination of multivalent linkers and their use in surface-based DNA sandwich hybridization assays. Dipodal silane is introduced as a means to fabricate amine-coated silica nanoparticles and its advantages compared to monopodal silanes are discussed. The use of dipodal silane in conjunction with three different polymer linkers (oxidized dextran, linear and 8-arm polyethylene glycol (PEG)) to immobilize single-stranded DNA to Cy5-doped nanoparticles is investigated and dynamic light scattering measurements and Fourier transform infrared spectroscopy are used to follow the progression of the functionalization of the nanoparticles. We observe a significant improvement in the binding stability of the single-stranded DNA when the dipodal silane and 8-arm PEG are used in combination, when compared to alternative conjugation strategies. Both 8mer and 22mer oligonucleotides are securely conjugated to the high-brightness nanoparticles and their availability to hybridize with a complementary strand is confirmed using solution-based DNA hybridization experiments. In addition, a full surface-based sandwich assay demonstrates the potential these nanoparticles have in the detection of less than 500 femtomolar of a DNA analogue of micro RNA, miR-451.
    No preview · Article · Sep 2015 · Nanotechnology
  • Source
    • "The change in integrated absorbance was measured, rather than an LSPR peak shift. Antigens were detected for concentrations in the region of 100 pg/mL (Endo, et al., 2006). "

    Full-text · Chapter · Dec 2011
  • Source
    • "In particular, when binding molecules to the surface of LSPparticles , the according increase in the refractive index causes the extinction resonances to red-shift, as reported in various studies on the real-time molecular binding monitored by simple optical transmission spectrometry [3] [4] [5]. Among the studied analytes, LSP-based detection has been essayed with, e.g., heavy metal ions [6], toxin [7], glucose [8], nucleic acids [9], biotin-streptavidin [10], or antigen-antibody interactions [11] [12]. An ordered array of similar particles is usually applied for a high signal-to-noise ratio, with recent developments aiming at single molecule detection [13] [14]. "
    [Show abstract] [Hide abstract]
    ABSTRACT: Noble metal nanoparticles show specific optical properties due to the excitation of localized surface plasmons that make them attractive candidates for highly sensitive bionanosensors. The underlying physical principle is either an analyte-induced modification of the dielectric properties of the medium surrounding the nanoparticle or an increase of the excitation and emission rates of an optically active analyte by the resonantly enhanced plasmon field. Either way, besides the nanoparticle geometry the dielectric properties of the metal and nanoscale surface roughness play an important role for the sensing performance. As the underlying principles are however not yet well understood, we aim here at an improved understanding by analyzing the optical characteristics of lithographically fabricated nanoparticles with different crystallinity and roughness parameters. We vary these parameters by thermal annealing and apply a thin gold film as a model system to retrieve modifications in the dielectric function. We investigate, on one hand, extinction spectra that reflect the far-field properties of the plasmonic excitation and, on the other hand, surface-enhanced Raman spectra that serve as a near-field probe. Our results provide improved insight into localized surface plasmons and their application in bionanosensing.
    Full-text · Article · Nov 2011 · BioNanoScience
Show more