|
|||||
|
|
Plasmonic nanoparticles assemblies templated by helical bacteria and resulting optical activity |
|
| Authors: | Wenchun Feng Usha Kadiyala Jiao Yan Yichun Wang Victor J. DiRita J. Scott VanEpps Nicholas A. Kotov |
| Affiliation: | 1. US Food and Drug Administration, Silver Spring, Maryland, USA Biointerfaces Institute, University of Michigan, Ann Arbor, Michigan, USA Department of Chemical Engineering, University of Michigan, Ann Arbor, Michigan, USA;2. Biointerfaces Institute, University of Michigan, Ann Arbor, Michigan, USA Department of Emergency Medicine, University of Michigan, Ann Arbor, Michigan, USA;3. Biointerfaces Institute, University of Michigan, Ann Arbor, Michigan, USA Department of Chemical Engineering, University of Michigan, Ann Arbor, Michigan, USA;4. Biointerfaces Institute, University of Michigan, Ann Arbor, Michigan, USA Department of Biomedical Engineering, University of Michigan, Ann Arbor, Michigan, USA;5. Department of Microbiology and Molecular Genetics, Michigan State University, East Lansing, Michigan, USA;6. Biointerfaces Institute, University of Michigan, Ann Arbor, Michigan, USA Department of Emergency Medicine, University of Michigan, Ann Arbor, Michigan, USA Department of Biomedical Engineering, University of Michigan, Ann Arbor, Michigan, USA Michigan Center for Integrative Research in Critical Care, University of Michigan, Ann Arbor, Michigan, USA Macromolecular Science and Engineering Program, University of Michigan, Ann Arbor, Michigan, USA;7. Biointerfaces Institute, University of Michigan, Ann Arbor, Michigan, USA |
| Abstract: | Plasmonic nanoparticles (NPs) adsorbing onto helical bacteria can lead to formation of NP helicoids with micron scale pitch. Associated chiroptical effects can be utilized as bioanalytical tool for bacterial detection and better understanding of the spectral behavior of helical self-assembled structures with different scales. Here, we report that enantiomerically pure helices with micron scale of chirality can be assembled on Campylobacter jejuni, a helical bacterium known for severe stomach infections. These organisms have right-handed helical shapes with a pitch of 1–2 microns and can serve as versatile templates for a variety of NPs. The bacteria itself shows no observable rotatory activity in the visible, red, and near-IR ranges of electromagnetic spectrum. The bacterial dispersion acquires chiroptical activity at 500–750 nm upon plasmonic functionalization with Au NPs. Finite-difference time-domain simulations confirmed the attribution of the chiroptical activity to the helical assembly of gold nanoparticles. The position of the circular dichroism peaks observed for these chiral structures overlaps with those obtained before for Au NPs and their constructs with molecular and nanoscale chirality. This work provides an experimental and computational pathway to utilize chiroplasmonic particles assembled on bacteria for bioanalytical purposes. |
| Keywords: | bacteria biotechnology C. jejuni circular dichroism gold nanoparticle mesoscale plasmonic plasmonic simulation |