Ratiometric Molecularly\nImprinted Particle Probes\nfor Reliable Fluorescence Signaling of Carboxylate-Containing Molecules

In addition to sensitivity, selectivity, and portability,\nchemical\nsensing systems must generate reliable signals and offer modular configurability\nto address various small molecule targets, particularly in environmental\napplications. We present a versatile, modular strategy utilizing ratiometric\nmolecularly imprinted particle probes based on BODIPY indicators and\ndyes for recognition and internal referencing. Our approach employs\npolystyrene core particles doped with a red fluorescent BODIPY as\nan internal standard, providing built-in reference for environmental\ninfluences. A molecularly imprinted polymer (MIP) recognition shell,\nincorporating a green-fluorescent BODIPY indicator monomer with a\nthiourea binding site for carboxylate-containing analytes, is grafted\nfrom the core particles in the presence of the analyte as the template.\nThe dual-fluorescent MIP probe detects fexofenadine as the model analyte\nwith a change in green emission signal referenced against a stable\nred signal, achieving a detection limit of 0.13 μM and a broad\ndynamic range from 0.16 μM to 1.2 mM, with good discrimination\nagainst other antibiotics in acetonitrile. By selecting a versatile\ndye scaffold and recognition element, this approach can be extended\nto other carboxylate-containing analytes and/or wavelength combinations,\npotentially serving as a robust multiplexing platform.