Lanthanide ions sensitized hydrogen-bonded organic framework as fluorescent sensing platform for ultra-low concentration breath ammonia detection

Abstract

Ammonia (NH3) as a biomarker of liver and kidney lesions, developing precision and credible exhaled ammonia fluorescent sensors is of major importance to replace time-consuming blood tests, while the insufficient sensitivity and weak response for low concentration analyte in expiratory limits their generalization and application. Herein, we adopt a “ligand-to-metal charge transfer-induced energy transfer (LMCT-ET)” strategy, through coordination post-synthetic modification, target introduction terbium (III) ions (Tb3+) into hydrogen-bonded organic framework (HOF). With the charge rearrangement and energy transfer between photoluminescence HOF-16 and lanthanide metal, a ratiometric fluorescence sensor has been successfully constructed and has achieved significant amplification of the response signal. Tb@HOF-16 realizes sensitive sensing of ultra-low concentration ammonia with the limit of detection of 36 ppb. Notably, Tb@HOF-16 is able to accurately quantify ammonia concentrations in patient’s exhaled components, and the analysis results have greatly positive correlation with blood ammonia testing. The visible fluorescent platform developed in this work provides a productive method for early diagnosis of liver and kidney lesions.