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Directional fluorescence emission co-enhanced by localized and propagating surface plasmons for biosensing
Yi Wang1, Lin Wu2, Ten It Wong3
1Centre for Biomimetic Sensor Science, School of Materials Science and Engineering, Nanyang Technological University, 50 Nanyang Drive, Singapore 637553. bliedberg@ntu.edu.sg and Wenzhou Institute of Biomaterials and Engineering, Chinese Academy of Sciences, Wenzhou, 325001 China. wangyi@wibe.ac.cn.
Simultaneous excitation of localized and propagating surface plasmons on nanohole arrays significantly enhances fluorescence intensity for bioassays. This plasmonic enhancement offers a pathway to ultra-sensitive biosensing applications.
Area of Science:
- Plasmonics
- Nanophotonics
- Biophysics
Background:
- Surface plasmons, including localized (LSPs) and propagating (PSPs), are crucial for light-matter interactions.
- Heterogeneous bioassays require sensitive detection methods for accurate results.
- Enhancing fluorescence intensity is key to improving the sensitivity of bioanalytical techniques.
Purpose of the Study:
- To investigate the simultaneous excitation of LSPs and PSPs on a nanohole array for fluorescence enhancement in bioassays.
- To de-convolute the origin of plasmon-enhanced fluorescence and identify optimization strategies.
- To assess the potential for implementing this technique in ultra-sensitive bioassays.
Main Methods:
- Fabrication of a thin metallic film with an array of nanoholes.
- Utilizing a Kretschmann configuration for surface plasmon excitation.
- Combining experimental measurements with electromagnetic simulations.
- Quantifying fluorescence intensity enhancement compared to control surfaces.
Main Results:
- Co-excitation of PSP and LSP modes on the nanohole array resulted in approximately 10^2-fold fluorescence enhancement compared to a flat gold surface under off-resonance conditions.
- The substrate supporting both PSPs and LSPs showed a 3-fold higher fluorescence signal than a flat surface with only resonant PSP excitation.
- Simulations predicted highly directional fluorescence emission and efficient fluorescence collection from the nanohole array substrate.
Conclusions:
- Simultaneous excitation of localized and propagating surface plasmons on nanohole arrays offers significant fluorescence enhancement for bioassays.
- Nanohole array substrates provide superior performance for surface plasmon-enhanced fluorescence spectroscopy compared to flat surfaces.
- This approach holds promise for developing ultra-sensitive biosensing platforms.
