Cu2+-Catechol Coordination-Enabled Chiral Fabry-Pérot Interferometer for Amplifying Weak Enantioselective Interactions.

Abstract

Efficient transduction of weak enantioselective adsorption into amplified optical signals remains challenging in label-free chiral sensing. Herein, we report a Cu2+-catechol coordination-enabled chiral Fabry-Pérot interferometer for amplified enantioselective sensing of catechol-containing chiral molecules. The sensing interface was constructed by in situ growing an l-glutamic-acid-modified MIL-125(Ti) layer within TiO2 nanotube Fabry-Pérot cavities, providing a homochiral porous microenvironment for differential enantiomer adsorption. Using DOPA enantiomers as model analytes, their distinct adsorption behaviors induce different local refractive-index changes, which are transduced into effective optical thickness variations by reflectometric interference spectroscopy. After target capture, Cu2+ ions coordinate with the catechol groups of adsorbed DOPA molecules, increasing interfacial loading and amplifying the refractive-index perturbation within the Fabry-Pérot cavity. This coordination-assisted amplification enlarges the optical response difference between DOPA enantiomers and enables sensitive discrimination with a detection limit down to 10-8 M under both static incubation and flow-through monitoring conditions. By integrating homochiral MOF recognition, Fabry-Pérot transduction, and Cu2+-catechol coordination amplification, this work provides a low-cost, label-free strategy for amplifying chiral host-guest interactions, with potential extension to catechol-containing enantiomers.

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