Development of whole synthetic enzyme-liquid crystal platforms for next generation sensor applications

Date

2025-8-29

Author

Karaman, Deniz

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Liquid crystal (LC)–aqueous soft interface sensors have shown potential for a wide range of analytes, including the tracking of their reactions. While these sensors have shown promise in studying enzymatic activity, their utilization has been dominated by natural enzymes. In this thesis, we introduce a whole-synthetic approach for detecting molecular species through their interactions with enzyme mimics. We employed highly stable fullerene-based synthetic enzyme mimics and performed structural and response characterizations of the LC–aqueous interfaces to track the catalytic hydrolysis of p-nitrophenyl acetate (pNPA) in solutions in contact with nematic 4-pentyl-4′-cyanobiphenyl (5CB) droplets. Building upon this approach, we introduce chemical modifications to these enzyme mimics to explore chemistry- dependent response characteristics of LC–aqueous interfaces. We employed polarized light microscopy to monitor temporal configuration changes of 5CB droplets during hydrolysis, while interfacial tension measurements and UV–Vis spectrophotometry provided insights into adsorption characteristics, interfacial structuration, and reaction kinetics. Our findings reveal two distinct interfacial structuring: enzyme-mimic–immobilized interfaces and interfaces characterized by a dynamic adsorption–desorption equilibrium of enzyme mimics, with no influence of LCs on the reaction kinetics. We showed that LC droplets exhibit an instantaneous response originating from bulk enzyme mimic–substrate interactions, with recovery times governed by the bulk phase composition. The tailored modifications of enzyme mimics strongly affect the LC droplet responsiveness to enzymatic pNPA hydrolysis. Overall, the design flexibility of these fullerene-based enzyme mimics enables precise tuning of interfacial properties, enhancing LC sensor sensitivity and supporting their application in biochemical sensing, environmental monitoring, and diagnostics. These findings offer new insights into LC-based sensing systems adaptable to diverse substrates and enzyme–substrate interactions.

Subject Keywords

Liquid crystals, Emulsions, Enzyme mimics, Hydrolysis, Response

URI

https://hdl.handle.net/11511/115637

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Graduate School of Natural and Applied Sciences, Thesis