A bi-functionalized metal-organic framework based on N-methylation and Eu3+ post-synthetic modification for highly sensitive detection of 4-Aminophenol (4-AP), a biomarker for aniline in urine

Abstract

4-Aminophenol (4-AP), which is a biomarker of aniline and represents the internal dose of aniline exposure in the human body, has attracted much attention for its detection in recent years. In this work, a bi-functionalized luminescent metal-organic framework (MOF), Eu@MOF-253-CH3, is designed and prepared through encapsulating the methyl groups and the Eu3+ cations into MOF-253 based on post-synthetic modification strategy. This study shows that the bi-functionalized Eu@MOF-253-CH3 can specifically recognize 4-AP upon luminescence quenching, while refraining from the interference of other coexisting species in urine. The Eu@MOF-253-CH3 hybrid as a 4-AP sensor also displays excellent performances including high water tolerance, good pH-independent stability, fast response, great selectivity and elevated sensitivity (0.5 μg mL−1) attributed to N-viologenized ligand. These results suggest the bi-functionalized Eu@MOF-253-CH3 can act as a promising sensor to practically monitor 4-AP's concentrations in human urine system, and then to realize the screening and pre-diagnosis of human health. Moreover, the possible sensing mechanisms are further explored at length.