Fluorescence Transduction of Liquid Crystal Ordering Transitions for Biosensing

Area of Science:

• Soft Matter Physics
• Materials Science
• Biotechnology

Background:

• Liquid crystal (LC) ordering transitions are sensitive to interfacial molecular interactions, forming the basis for optical biosensors.
• Current LC biosensors primarily use polarized-light microscopy, limiting quantification and practical application.

Purpose of the Study:

• To develop a fluorescence-based method for quantifying LC ordering transitions.
• To create a novel biosensing platform for pathogen detection using LC emulsions and aggregation-induced emission (AIE) polymers.

Main Methods:

• Synthesized amphiphilic block copolymers with AIE motifs capable of dynamic covalent conjugation with antibodies.
• Utilized reversible imine chemistry for antibody conjugation.
• Designed LC emulsions where polymer localization and AIE unit concentration correlate with LC configuration (monopolar vs. radial).
• Integrated a ratiometric reference dye for enhanced robustness.

Main Results:

• Demonstrated conversion of LC ordering transitions into quantitative fluorescence ON/OFF states.
• Achieved sensitive detection of *Salmonella enterica* serovar Typhimurium with limits down to 10^2 cells/mL.
• Observed rapid fluorescence responses (approximately 1 hour) upon pathogen recognition.

Conclusions:

• Established fluorescence transduction of LC ordering transitions as a versatile and portable sensing paradigm.
• Bridged advancements in soft matter design with practical diagnostic applications.
• Showcased a robust biosensing platform with potential for real-world pathogen detection.