A new surface ion-imprinted covalent organic framework nanoprobe for selective determination of trace uranium via...

In environmental monitoring and nuclear emergency response, uranium-induced environmental pollution and nuclear incidents have garnered significant attention. Therefore, it is of great importance to establish a rapid, highly selective and sensitive method for detecting UO₂²⁺. In this study, the 50 nm Fe₃O₄ was used as the substrate, UO₂²⁺ as the template ion,1,3,5-benzenetricarboxaldehyde,2,4,6-trihydroxy(TFP) and p-phenylenediamine (PDA) as functional monomers of the covalent organic framework (COF) ion-imprinted layer to synthesize a new COF probe Fe₃O₄ _{50 nm}@TFP-PDA. This probe exhibits a resonance Rayleigh scattering (RRS) peak at 560 nm. In the presence of UO₂²⁺ and ascorbic acid, the COF probe demonstrates a pronounced RRS energy transfer (RRS-ET) effect, to establish a rapid, highly sensitive and selective method for detection of UO₂²⁺. The detection range is 0.20-19 nmol/L, with a detection limit of 0.024 nmol/L UO₂²⁺. This method was applied to determine trace UO₂²⁺ in seawater, with recovery of 91.0-108.8% and relative standard deviation of 1.01-6.05%. This work provides a new COF probe-RRS detection strategy for trace uranium, and has certain application potential in food safety and environmental protection.