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 UO22+ 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 UO22+ would induce aggregation of VPA-AuNPs, resulting in the color change from winered to blue, and red-shift of the ultraviolet-visible (UV-vis) spectra. The UO22+ assay based on VPA-AuNPs showed good selectivity and sensitivity, with a limit of detection to be approximately 2.0 mu M by naked eyes and 1.07 mu M 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 UO22+ with different concentrations, and the concentration of UO22+ samples could be conveniently exported by the calculated univariate calibration curves. This method shows good feasibility for on-site UO22+ detection in an aqueous solution. (C) 2021 Elsevier B.V. All rights reserved.