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Plasmonic nanoparticles assemblies templated by helical bacteria and resulting optical activity
Wenchun Feng1,2,3, Usha Kadiyala2,4, Jiao Yan2,3
1US Food and Drug Administration, Silver Spring, Maryland, USA.
Chirality
|April 23, 2020
Summary
Researchers assembled gold nanoparticles onto Campylobacter jejuni bacteria, creating chiral structures. This novel bioanalytical tool detects bacteria using chiroptical effects, enhancing spectral analysis of helical assemblies.
Area of Science:
- Plasmonics
- Bacteriology
- Chiroptical Spectroscopy
Background:
- Helical bacteria can template plasmonic nanoparticle (NP) assemblies, forming chiral structures with potential bioanalytical applications.
- Campylobacter jejuni, a helical bacterium, serves as a template for creating micron-scale chiral NP helicoids.
- Understanding the spectral behavior of these self-assembled chiral structures is crucial for bioanalytical tool development.
Purpose of the Study:
- To assemble enantiomerically pure helices on Campylobacter jejuni using plasmonic nanoparticles.
- To investigate the chiroptical properties of these bacterial-NP assemblies.
- To establish a bioanalytical method for bacterial detection utilizing chiroplasmonic effects.
Main Methods:
- Utilizing Campylobacter jejuni as a natural helical template for nanoparticle assembly.
- Functionalizing bacteria with gold nanoparticles (Au NPs) to form NP helicoids.
- Characterizing chiroptical activity using spectroscopy (500-750 nm).
- Employing finite-difference time-domain (FDTD) simulations to confirm chiroptical attribution.
Main Results:
- Enantiomerically pure helices with micron-scale chirality were successfully assembled on Campylobacter jejuni.
- Bacterial dispersions functionalized with Au NPs exhibited chiroptical activity in the 500-750 nm range.
- FDTD simulations confirmed that the helical assembly of Au NPs is responsible for the observed chiroptical activity.
- The circular dichroism peaks of the bacterial-NP constructs align with those of other chiral Au NP assemblies.
Conclusions:
- Campylobacter jejuni can serve as a versatile template for assembling chiral plasmonic structures.
- Functionalized bacteria exhibit significant chiroptical activity, enabling potential bacterial detection.
- This study presents a combined experimental and computational approach for developing bioanalytical tools based on bacterial-templated chiroplasmonic assemblies.
