Various methods have been developed in recent years for the determination of uranyl ion by making use of uranyl-specific DNAzymes. However, many of them suffer from hydrolysis by nucleases present in samples such as body fluids. We report here on an uranyl-specific nuclease-resistant DNA aptamer (UApt) as the recognition element, and how gold nanoparticles (AuNPs) can be used as signal reporters in the respective assay. The presence of uranyl ion leads to a conformational change of UApt, and this results in the dispersion of AuNPs and a decreas...