A cation-mediated fluorescence enhanced hydrogel for the sensitive detection of uranyl ions in water

Uranium, in terms of both its radioactivity and chemical toxicity, poses significant environmental and health risks when released through nuclear industry activities and its mining. The sensitive detection of uranyl ions (UO₂²⁺) in wastewater is crucial for mitigating these risks and safeguarding public health. Herein, we present an innovative approach by synthesizing the functional monomer 6-(3-(2-(methacryloyloxy)ethyl)ureido)picolinate (K6MUPA) to create a novel europium ion (Eu³⁺)-K6MUPA-AAm hydrogel sensor. Through simple ionic coordination, europium ions (Eu³⁺) were incorporated into the hydrogel, which initially exhibited weak fluorescence. Remarkably, the fluorescence intensity was significantly enhanced by the cationic interactions between UO₂²⁺ and Eu³⁺, enabling highly sensitive and selective detection of UO₂²⁺. The sensor demonstrated a linear response in the range of 1-100 nmol L^-1 (F - F₀ = 10.52C_uranyl + 97.38) with a detection limit of 1 nmol L^-1. Practical applicability was confirmed through real sample analysis, achieving excellent recoveries of 100.18-107.36%. This work not only advances UO₂²⁺ detection but also highlights the potential of innovative hydrogel-based sensors for environmental monitoring.