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Ramanenka A.A.,Belarusian State University | Vaschenko S.V.,Belarusian State University | Vaschenko S.V.,National Academy of Sciences of Belarus | Stankevich V.V.,National Academy of Sciences of Belarus | And 3 more authors.
Journal of Applied Spectroscopy | Year: 2014

Plasmonic enhancement of the luminescence of fl uorescein isothiocyanate and human immunoglobulin conjugates near silver nanoparticles was investigated as functions of the nanoparticle-conjugate distance and the excitation polarization. The maximum luminescence enhancement of 7.4 was achieved for p-polarized excitation and nanoparticle-conjugate distance 3.3 nm. The luminescence enhancement factor increased experimentally for p-polarized excitation and decreased for s-polarized excitation as compared with unpolarized excitation. © 2014 Springer Science+Business Media New York.

Kozhukh S.,National Academy of Sciences of Belarus | Zhukovsky S.,University of Toronto | Yurkevich I.,National Academy of Sciences of Belarus | Stepkova S.,National Academy of Sciences of Belarus | And 3 more authors.
Journal of Nanophotonics | Year: 2012

Based on analysis of light propagation in multiple cavity aperiodic structures, a filter with three narrow passbands with high transmission is designed. The design is implemented for use in express early-stage oral cancer screening by means of Raman spectroscopy. A combination of SiO2/Nb2O5 is used in a vacuum deposition process to ensure high refractive index contrast and durability of materials. The approach enables the development of simple and affordable Raman testers for multiple medical, forensic, and environmental applications. © 2012 Society of Photo-Optical Instrumentation Engineers (SPIE).

Guzatov D.V.,Kupala State University | Vaschenko S.V.,National Academy of Sciences of Belarus | Vaschenko S.V.,Belarusian State University | Stankevich V.V.,National Academy of Sciences of Belarus | And 3 more authors.
Journal of Physical Chemistry C | Year: 2012

Metal-enhanced fluorescence of molecular probes in plasmonic nanostructures offers highly sensitive chemical and biomedical analyses, but a comprehensive theory of the phenomenon is far from being complete. In this study, a systematic theoretical analysis is provided for overall luminescence enhancement/quenching for fluorophores near silver spherical nanoparticles. The approach accounts for local intensity enhancement, radiative and nonradiative rates modification, light polarization, molecule position, and its dipole moment orientation. Numerical modeling has been performed for fluorescein-based labels (e.g., Alexa Fluor 488) widely used in biomedical studies and development. The maximal enhancement exceeding 50 times is predicted for nanoparticle diameter 50 nm, the optimal excitation wavelength being 370 nm. For long-wave excitation, bigger particles are more efficient. The experiments with a fluorescein isothiocyanate conjugate of bovine serum albumin confirmed theoretical predictions. The results provide an extensive and promising estimate for simple and affordable silver-based nanostructures to be used in fluorescent plasmonic sensors. © 2012 American Chemical Society.

Vaschenko S.,B. I. Stepanov Institute of Physics | Ramanenka A.,B. I. Stepanov Institute of Physics | Kulakovich O.,B. I. Stepanov Institute of Physics | Muravitskaya A.,B. I. Stepanov Institute of Physics | And 4 more authors.
Procedia Engineering | Year: 2016

A model immunoassay test system is proposed based on metal enhanced photoluminescence to analyze low concentrations of alpha-fetoprotein, a tumor marker. Antigen-antibody reaction was performed on polystyrene plates coated with silver nanoparticles to increase sensitivity of fluorescent immunoassay and signal-to-noise ratio as compared to silver-free system. The proposed test system model uses layer-by-layer assembly approach, LED excitation and nanowatt photodetection set-up, so it is characterized by smaller probe volume, fast analysis and simplicity. The proposed model system offers alpha-fetoprotein detection at concentrations used in clinical practice. Photostability and photoluminescence enhancement for labeled alpha-fetoprotein antibodies on a silver substrate were found to depend on antibodies concentration. Labeled antibodies photostability on substrates was found to deviate within 20% as compared to silver-free samples whereas photoluminescence intensity enhancement is typically in the range of 6-8 times. © 2016 The Authors.

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