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Journal of Biomedical Optics

Reflected light microspectroscopy for single-nanoparticle biosensing
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Paper Abstract

Conventional and dark-field microscopy in the transmission mode is extensively used for single plasmonic nanoparticle (NP) imaging and spectral analysis. However, application of the transmission mode for real-time biosensing to single NP poses strict limitations on the size and material properties of the microfluidic system. This article proposes a simple optical technique based on reflected light microscopy to perform microspectroscopy of a single NP placed in a conventional, nontransparent liquid delivery system. The insertion of a variable spot diaphragm in the optical path reduces the interference effect that occurs at the NP-substrate interface and improves the signal-to-noise ratio in NP imaging. Using this method, we demonstrated spatial imaging and spectral analyses of 60-, 80-, and 100-nm single gold NPs. A single-NP sensor based on a 100-nm NP was used for real-time measurement of bulk refractive index changes in the microfluidic channel and for detection of fast dynamic poly(ethylene glycol) attachment to the NP surface. Finally, electrochemical single-particle microspectroscopy was demonstrated by using a methylene blue electroactive redox tag. The proposed optical approach is expected to significantly improve the miniaturization and multiplexing capabilities of high-throughput biosensing based on single NP.

Paper Details

Date Published: 21 September 2015
PDF: 7 pages
J. Biomed. Opt. 20(9) 097001 doi: 10.1117/1.JBO.20.9.097001
Published in: Journal of Biomedical Optics Volume 20, Issue 9
Show Author Affiliations
Sergiy Patskovsky, Ecole Polytechnique de Montréal (Canada)
Michel Meunier, Ecole Polytechnique de Montréal (Canada)

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