Biomacromolecular stereostructure mediates mode hybridization in chiral plasmonic nanostructures

Jack, C., Karimullah, A. S. , Leyman, R., Tullius, R., Rotello, V. M., Cooke, G. , Gadegaard, N. , Barron, L. D. and Kadodwala, M. (2016) Biomacromolecular stereostructure mediates mode hybridization in chiral plasmonic nanostructures. Nano Letters, 16(9), pp. 5806-5814. (doi: 10.1021/acs.nanolett.6b02549) (PMID:27547978)

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The refractive index sensitivity of plasmonic fields has been exploited for over 20 years in analytical technologies. While this sensitivity can be used to achieve attomole detection levels, they are in essence binary measurements that sense the presence/absence of a predetermined analyte. Using plasmonic fields, not to sense effective refractive indices but to provide more “granular” information about the structural characteristics of a medium, provides a more information rich output, which affords opportunities to create new powerful and flexible sensing technologies not limited by the need to synthesize chemical recognition elements. Here we report a new plasmonic phenomenon that is sensitive to the biomacromolecular structure without relying on measuring effective refractive indices. Chiral biomaterials mediate the hybridization of electric and magnetic modes of a chiral solid-inverse plasmonic structure, resulting in a measurable change in both reflectivity and chiroptical properties. The phenomenon originates from the electric-dipole–magnetic-dipole response of the biomaterial and is hence sensitive to biomacromolecular secondary structure providing unique fingerprints of α-helical, β-sheet, and disordered motifs. The phenomenon can be observed for subchiral plasmonic fields (i.e., fields with a lower chiral asymmetry than circularly polarized light) hence lifting constraints to engineer structures that produce fields with enhanced chirality, thus providing greater flexibility in nanostructure design. To demonstrate the efficacy of the phenomenon, we have detected and characterized picogram quantities of simple model helical biopolymers and more complex real proteins.

Item Type:Articles
Glasgow Author(s) Enlighten ID:Kadodwala, Professor Malcolm and Cooke, Professor Graeme and TULLIUS, Ryan and Karimullah, Dr Affar and Barron, Professor Laurence and Gadegaard, Professor Nikolaj and JACK, CALUM and Leyman, Mr Ross
Authors: Jack, C., Karimullah, A. S., Leyman, R., Tullius, R., Rotello, V. M., Cooke, G., Gadegaard, N., Barron, L. D., and Kadodwala, M.
College/School:College of Science and Engineering > School of Chemistry
College of Science and Engineering > School of Engineering > Biomedical Engineering
Journal Name:Nano Letters
Publisher:American Chemical Society
ISSN (Online):1530-6992
Published Online:22 August 2016
Copyright Holders:Copyright © 2016 American Chemical Society
First Published:First published in Nano Letters 16(9): 5806-5814
Publisher Policy:Reproduced under a Creative Commons License

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Project CodeAward NoProject NamePrincipal InvestigatorFunder's NameFunder RefLead Dept
618701Plasmon-Enhanced Chiroptical SensorsMalcolm KadodwalaEngineering & Physical Sciences Research Council (EPSRC)EP/K034936/1CHEM - CHEMISTRY