Effect of dielectric spacer thickness on signal intensity of surface plasmon field-enhanced fluorescence spectroscopy

Takashi Murakami, Yusuke Arima, Mitsuaki Toda, Hiromi Takiguchi, Hiroo Iwata

Research output: Contribution to journalArticle

11 Citations (Scopus)

Abstract

Surface plasmon field-enhanced fluorescence spectroscopy (SPFS) combines enhanced field platform and fluorescence detection. Its advantages are the strong intensity of the electromagnetic field and the high signal/noise (S/N) ratio due to the localized evanescent field at the water/metal interface. However, the energy transfer from the fluorophore to the metal surface diminishes the fluorescence intensity, and this reduces the sensitivity. In this study, we tested whether polystyrene (PSt) could act as a dielectric layer to suppress the energy transfer from the fluorophore to the metal surface. We hypothesized that this would improve the sensitivity of SPFS-based immunoassays. We used α-fetoprotein (AFP) as a model tumor biomarker in the sandwich-type immunoassay. We determined the relationship between fluorescent signal intensity and PSt layer thickness and compared this to theoretical predictions. We found that the fluorescence signal increased by optimally controlling the thickness of the PSt layer. Our results indicated that the SPFS-based immunoassay is a promising clinical diagnostic tool for quantitatively determining the concentrations of low-level biomarkers in blood samples.

Original languageEnglish
Pages (from-to)632-639
Number of pages8
JournalAnalytical Biochemistry
Volume421
Issue number2
DOIs
Publication statusPublished - Feb 15 2012
Externally publishedYes

All Science Journal Classification (ASJC) codes

  • Biophysics
  • Biochemistry
  • Molecular Biology
  • Cell Biology

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