Topological defects at smectic interfaces as a potential tool for the biosensing of living microorganisms

TL;DR

This paper explores how smectic liquid crystals and their topological defects can be used to detect and distinguish bacteria, offering a novel approach for biosensing of microorganisms based on optical and defect analysis.

Contribution

It introduces a new method utilizing smectic LC interfaces and topological defects for bacterial detection and concentration measurement, advancing biosensing technology.

Findings

Different bacteria induce distinct optical responses in smectic LCs.

Topological defects correlate with bacterial concentration levels.

The approach enables differentiation between bacterial species.

Abstract

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 solutions 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 demonstrate the significant potential of smectic LCs and their defects for biosensing applications and contribute to our understanding of bacteria- LC interactions, paving the way for advancements in pathogen detection and protein-based sensing.