A sensitive resonance light scattering assay for uranyl ion based on the conformational change of a nuclease-resistant aptamer and gold nanoparticles acting as signal reporters

摘要

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 decrease in the intensity of resonance light scattering (RLS) at around 573.0 nm. The conformational changes were also studied by polyacrylamide gel electrophoresis, circular dichroism, and UV-vis spectroscopy. The RLS signals are linearly related to the concentration of uranyl ion in the 22 to 550 nM range, with a detection limit of 6.7 nM. This method is more simple and robust than others owing to use of a UApt without a ribonucleotide adenosine. It has been successfully applied to the determination of uranyl ion in real samples. We presume that this method may be extended to the determination of other analytes by making use of the corresponding aptamer for the target.