Colorimetric detection for uranyl ions in water using vinylphosphonic acid functionalized gold nanoparticles based on smartphone

A simple and portable colorimetric sensor for colorimetric detection of UO 2 2+ in aqueous solution based on vinylphosphonic acid functionalized gold nanoparticles (VPA-AuNPs) has been developed. The VPA-AuNPs solution was prepared by sodium borohydride reduction in the presence of vinylphosphonic acid. The addition of UO 2 2+ would induce aggregation of VPA-AuNPs, resulting in the color change from wine-red to blue, and red-shift of the ultraviolet–visible (UV–vis) spectra. The UO 2 2+ assay based on VPA-AuNPs showed good selectivity and sensitivity, with a limit of detection to be approximately 2.0 μM by naked eyes and 1.07 μM by UV–vis (S/N = 3) respectively. Additionally, a smartphone with a free application named “ PhotoMetrix ” was employed to estimate the color intensities (red, green, blue value) of VPA-AuNPs in the presence of UO 2 2+ with different concentrations, and the concentration of UO 2 2+ samples could be conveniently exported by the calculated univariate calibration curves . This method shows good feasibility for on-site UO 2 2+ detection in an aqueous solution.