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Characterizing the anchoring properties of smectic liquid crystals (LCs) in contact with bacterial solutions is crucial for developing biosensing platforms. In this study, we investigate the anchoring properties of a smectic LC when exposed to Bacillus subtilis and Escherichia coli bacterial suspensions using interfaces with known anchoring properties. By monitoring the optical response of the smectic film, we successfully distinguish different types of bacteria, leveraging the distinct changes in the LC’s response. Through a comprehensive analysis of the interactions between bacterial proteins and the smectic interface, we elucidate the potential underlying mechanisms responsible for these optical changes. Additionally, we introduce the utilization of topological defects, the focal conic domains (FCDs), at the smectic interface as an indicative measure of the bacterial concentration. Our findings contribute to the understanding of bacteria–LC interactions and demonstrate the significant potential of smectic LCs and their defects for biosensing applications, paving the way for advancements in pathogen detection and protein-based sensing.
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Focal conic flowers, dislocation rings, and undulation textures in smectic liquid crystal Janus droplets
Liquid crystalline phases of matter often exhibit visually stunning patterns or textures. Mostly, these liquid crystal (LC) configurations are uniquely determined by bulk LC elasticity, surface anchoring conditions, and confinement geometry. Here, we experimentally explore defect textures of the smectic LC phase in unique confining geometries with variable curvature. We show that a complex range of director configurations can arise from a single system, depending on sample processing procedures. Specifically, we report on LC textures in Janus drops comprised of silicone oil and 8CB in its smectic-A LC phase. The Janus droplets were made in aqueous suspension using solvent-induced phase separation. After drop creation, smectic layers form in the LC compartment, but their self-assembly is frustrated by the need to accommodate both the bowl-shaped cavity geometry and homeotropic (perpendicular) anchoring conditions at boundaries. A variety of stable and metastable smectic textures arise, including focal conic domains, dislocation rings, and undulations. We experimentally characterize their stabilities and follow their spatiotemporal evolution. Overall, a range of fabrication kinetics produce very different intermediate and final states. The observations elucidate assembly mechanisms and suggest new routes for fabrication of complex soft material structures in Janus drops and other confinement geometries.
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- Award ID(s):
- 2003659
- PAR ID:
- 10421912
- Date Published:
- Journal Name:
- Soft Matter
- Volume:
- 18
- Issue:
- 23
- ISSN:
- 1744-683X
- Page Range / eLocation ID:
- 4360 to 4371
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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- Free Publicly Accessible Full Text
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Accepted Manuscript1.0
- Journal Article:
- https://doi.org/10.1039/D1SM01623G
