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

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.