Engineered Fullerene-Based Enzyme Mimics for Enhanced Sensing of Aqueous-Phase Reactions Using Liquid Crystals

The responsive interfaces formed by thermotropic liquid crystals (LC) and aqueous phases have been utilized in reactive and catalytic applications, yet their utilization in enzymatic studies has been dominated by natural enzymes. We introduced fullerene-based enzyme mimics and investigated the enzyme mimic-chemistry-dependent response characteristics of LC–aqueous interfaces. We employed hydrophilic and hydrophobic modifications to the fullerene-based enzyme mimics and performed structure and response characterizations of the LC–aqueous interfaces for tracking aqueous-phase catalytic hydrolysis of p-nitrophenyl acetate (pNPA) in solutions in contact with nematic 4-pentyl-4’-cyanobiphenyl (5CB) droplets. Polarized light microscopy revealed temporal 5CB droplet configuration changes upon substrate hydrolysis, while interfacial tension measurements and UV–vis spectrophotometry provided insight into adsorption characteristics, interfacial structuration, and reaction kinetics. Our findings demonstrated two distinct interfacial structuring: the enzyme-immobilized interfaces and the interfaces formed with the adsorption–desorption equilibrium of enzyme mimics. We showed that the tailored modifications of fullerene-based enzyme mimics significantly influenced the LC responsiveness toward enzymatic pNPA hydrolysis. The design flexibility of fullerene-based enzyme mimics allows for fine-tuned control of interfacial properties, significantly improves LC sensitivity, and promises to advance synthetic enzyme designs for use in biochemical sensing, environmental monitoring, and diagnostic technologies.