Article

Detection of a biomarker for Alzheimer's disease from synthetic and clinical samples using a nanoscale optical biosensor

Department of Chemistry, Northwestern University, Evanston, Illinois, United States
Journal of the American Chemical Society (Impact Factor: 11.44). 03/2005; 127(7):2264-71. DOI: 10.1021/ja044087q
Source: PubMed

ABSTRACT A nanoscale optical biosensor based on localized surface plasmon resonance (LSPR) spectroscopy has been developed to monitor the interaction between the antigen, amyloid-beta derived diffusible ligands (ADDLs), and specific anti-ADDL antibodies. Using the sandwich assay format, this nanosensor provides quantitative binding information for both antigen and second antibody detection that permits the determination of ADDL concentration and offers the unique analysis of the aggregation mechanisms of this putative Alzheimer's disease pathogen at physiologically relevant monomer concentrations. Monitoring the LSPR-induced shifts from both ADDLs and a second polyclonal anti-ADDL antibody as a function of ADDL concentration reveals two ADDL epitopes that have binding constants to the specific anti-ADDL antibodies of 7.3 x 10(12) M(-1) and 9.5 x 10(8) M(-1). The analysis of human brain extract and cerebrospinal fluid samples from control and Alzheimer's disease patients reveals that the LSPR nanosensor provides new information relevant to the understanding and possible diagnosis of Alzheimer's disease.

1 Follower
 · 
202 Views
  • [Show abstract] [Hide abstract]
    ABSTRACT: Large area monolayer of self-assembled polystyrene sphere (PS) arrays were formed by an interface self-assembly method and the gap of PS was adjusted by O2 plasma treatment (OPT). After different duration of OPT, the spacing between the PSs varied from 5 to 88 nm. Then, 20 nm Au film was deposited on the PS arrays by electron beam deposition. The absorption peaks of Au-coated PS array red-shifted obviously by changing the gap of PS. The new absorption peaks emerged when the gap of the PS decreased to about 20 nm. The surface plasmon resonance (SPR) was employed to explain the absorption proportion of this Au-PS structure. These micro-nano structures exhibit tunable SPR bands, which may be useful to the applications in some research fields, such as biosensing, single molecule detection, and novel optoelectronic devices.
    Plasmonics 06/2014; 9(3):565-571. DOI:10.1007/s11468-013-9665-0 · 2.74 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: Herein, we combine the advantage of aptamer technique with the amplifying effect of an enzyme-free signal-amplification and Au nanoparticles (NPs) to design a sensitive surface plasmon resonance (SPR) aptasensor for detecting small molecules. This detection system consists of aptamer, detection probe (c-DNA1) partially hybridizing to the aptamer strand, Au NPs-linked hairpin DNA (Au-H-DNA1), and thiolated hairpin DNA (H-DNA2) previously immobilized on SPR gold chip. In the absence of target, the H-DNA1 possessing hairpin structure cannot hybridize with H-DNA2 and thereby Au NPs will not be captured on the SPR gold chip surface. Upon addition of target, the detection probe c-DNA1 is forced to dissociate from the c-DNA1/aptamer duplex by the specific recognition of the target to its aptamer. The released c-DNA1 hybridizes with Au-H-DNA1 and opens the hairpin structure, which accelerate the hybridization between Au-H-DNA1 and H-DNA2, leading to the displacement of the c-DNA1 through a branch migration process. The released c-DNA1 then hybridizes with another Au-H-DNA1 probe, and the cycle starts anew, resulting in the continuous immobilization of Au-H-DNA1 probes on the SPR chip, generating a significant change of SPR signal due to the electronic coupling interaction between the localized surface plasma of the Au NPs and the surface plasma wave. With the use of adenosine as a proof-of-principle analyte, this sensing platform can detect adenosine specifically with a detection limit as low as 0.21pM, providing a simple, sensitive and selective protocol for small target molecules detection. Copyright © 2015 Elsevier B.V. All rights reserved.
    Analytica chimica acta 02/2015; 871. DOI:10.1016/j.aca.2015.02.028 · 4.52 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: We implement a simple and fast technique to detect spectral shifts in the light scattering of gold nanoparticles due to refractive index changes of the surrounding medium. Spectral shifts are detected using spectrally balanced photon counting from the scattering spectrum of colloidal gold nanoparticles. We demonstrate the use of this technique for sensing ethanol concentration down to 0.1 M.
    Sensors and Actuators B Chemical 08/2012; 171-172:1269-1271. DOI:10.1016/j.snb.2012.04.053 · 3.84 Impact Factor

Preview

Download
11 Downloads
Available from