Functionalized lanthanide coordination polymer nanoparticles for selective sensing of hydrogen peroxide in biological fluids

Abstract

Lanthanide coordination polymers have recently emerged as very fascinating sensing materials due to their tunable structures and unique optical properties. However, a major problem concerning the applications of lanthanide coordination polymers for fluorescent sensing is their unselective recognition to analytes. In this work, a direct post-modification strategy was employed to prepare functionalized lanthanide coordination polymer nanoparticles (Phe/Tb-CPBA CPNPs) with specific response ability to hydrogen peroxide (H₂O₂) by using phenylalanine (Phe) as bridging ligands, terbium ions (Tb³⁺) as metal nodes and carboxyphenylboronic acids (CPBAs) as guest ligands. Phe/Tb-CPBA CPNPs emit a strong green fluorescence due to the removal of coordinated water molecules and the sensitization effect of CPBA. Upon the addition of H₂O₂, however, the quenched fluorescence of Phe/Tb-CPBA CPNPs can be observed owing to an intramolecular charge transfer effect. This finding led to a method for the quantitation of H₂O₂ in the 6 μM to 1 mM concentration range and with a detection limit at 2 μM. Because of the chemoselective H₂O₂-mediated oxidative deboronation, Phe/Tb-CPBA CPNPs as fluorescent sensors exhibit excellent selectivity to H₂O₂. Furthermore, Phe/Tb-CPBA CPNPs were successfully used to measure the level of H₂O₂ in urine samples and showed satisfactory results. We envision that the presented strategy could be extended to design other functionalized coordination polymers with desired functions for various biomedical applications.