Polarization-based immunoassay in aqueous solution using Au nanoparticle-labeled antibody

N. Mizuno, Y. Takeshita, J. Kobayashi, K. Esashika, Toshiharu Saiki

Research output: Contribution to journalArticle

2 Citations (Scopus)

Abstract

Here we describe an ultrasensitive antigen-antibody immunoassay using gold nanoparticles (AuNPs). Polarization microscopy is used to discriminate individual AuNP dimers from isolated single AuNPs by means of their Brownian motion in aqueous solution. The optical anisotropy and rotational diffusion time were measured to provide accurate and robust discrimination. Since the size of a naked antibody is comparable to that of an AuNP, the distance between two AuNPs (inter-dimer distance) is rather large, and therefore the optical anisotropy is seriously degraded. To address this problem, we digested the antibody with the protease pepsin to reduce the distance. Autocorrelation analysis allowed discrimination of the difference in optical anisotropy and rotational diffusion time. Setting an appropriate threshold for the measurement enabled sufficient accuracy in the discrimination.

Original languageEnglish
Pages (from-to)75-78
Number of pages4
JournalApplied Physics A: Materials Science and Processing
Volume115
Issue number1
DOIs
Publication statusPublished - 2014

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Antibodies
Polarization
Nanoparticles
Gold
Optical anisotropy
Dimers
Brownian movement
Pepsin A
Antigens
Autocorrelation
Microscopic examination
Peptide Hydrolases

ASJC Scopus subject areas

  • Materials Science(all)
  • Chemistry(all)

Cite this

Polarization-based immunoassay in aqueous solution using Au nanoparticle-labeled antibody. / Mizuno, N.; Takeshita, Y.; Kobayashi, J.; Esashika, K.; Saiki, Toshiharu.

In: Applied Physics A: Materials Science and Processing, Vol. 115, No. 1, 2014, p. 75-78.

Research output: Contribution to journalArticle

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