Colorimetric Detection of UO 2+ ₂ Using Gold Nanoparticles Immobilized with Pillar[5]arene Complexes with Nitrophenyldiacetic Acids as a Chemoprobe.

Uranium is a crucial raw material in the nuclear energy industry; however, its radioactive nature makes it a critically damaging component to both the atmosphere and human health. In this study, we report a simple and cost-effective selective colorimetric detection technique for UO22+ using nitrophenyldiacetic acids (NPD)-functionalized gold nanoparticles (Au NPs 1). The hybrid Au NPs 1 can be induced to aggregate in the presence of UO22+ ions. UO22+ can be recognized by the colorimetric response of hybrid Au NPs 1, which can be observed by a UV-Vis spectrophotometer and it is easily detectable by the naked eye. The hybrid Au NPs 1 bound by UO22+ possess a good selective response compared to other metal ions (Li+, Na+, K+, Rb+, Cs+, Ca2+, Mg2+, Ba2+, Ni2+, Zn2+, and Co2+), which can be observed by a prominent color change. The color of the hybrid Au NPs 1 changed from red to dark red upon addition of UO22+ in the presence of other metal ions. Job's plot demonstrates that one NPD moiety attached onto the surface of Au NPs 1 forms 1: 1 stoichiometry with UO22+, hence providing a simple and effective colorimetric sensor for the real-time detection of UO22+.