Lanthanide-based Single-Chain Nanoparticles as "Visual" Pass/Fail Sensors of Maximum Permissible Concentration of Cu2+ Ions in Drinking Water.

Abstract

The maximum permissible concentration (m.p.c.) of Cu2+ ions in drinking water, as set by the World Health Organization (WHO) is m.p.c. (Cu2+)WHO = 30 μM, whereas the US Environmental Protection Agency (EPA) establishes a more restrictive value of m.p.c. (Cu2+)EPA = 20 μM. Herein, we develop-for the first time ever-a family of m.p.c. (Cu2+) "visual" pass/fail sensors based on water-soluble lanthanide-containing single-chain nanoparticles (SCNPs) exhibiting an average hydrodynamic diameter less than 10 nm. Both europium (Eu)- and terbium (Tb)-based SCNPs allow excessive Cu2+ to be readily detected in water, as indicated by the red-to-transparent and green-to-transparent changes, respectively, under ultra-violet (UV) light irradiation, occurring at 30 μM Cu2+ in both cases. Complementary, dysprosium (Dy)-based SCNPs show a yellow color-to-transparent transition under UV light irradiation at approximately 15 μM Cu2+. Eu-, Tb- and Dy-containing SCNPs prove to be selective for Cu2+ ions as they do not respond against other metal ions, such as Fe2+, Ag+, Co2+, Ba2+, Ni2+, Hg2+, Pb2+, Zn2+, Fe3+, Ca2+, Mn2+, Mg2+ or Cr3+. These new m.p.c. (Cu2+) "visual" pass/fail sensors are thoroughly characterized by a combination of techniques, including size exclusion chromatography, dynamic light scattering, inductively coupled plasma-mass spectrometry, as well as infrared, UV and fluorescence spectroscopy. This article is protected by copyright. All rights reserved.