A highly selective magnetic sensor with functionalized Fe/Fe3O4 nanoparticles for detection of Pb2+

A magnetic sensor for detection of Pb2+ has been developed based on Fe/Fe3O4 nanoparticles modified by 3-(3,4-dihydroxyphenyl)propionic acid (DHCA). The carboxyl groups of DHCA have a strong affinity to coordination behavior of Pb2+ thus inducing the transformation of Fe/Fe3O4 nanoparticles from a dispersed to an aggregated state with a corresponding decrease, then increase in transverse relaxation time (T-2) of the surrounding water protons. Upon addition of the different concentrations of Pb2+ to an aq. solution of DHCA functionalized Fe/Fe3O4 nanoparticles (DHCA-Fe/Fe3O4 NPs) ([Fe] = 90 mu mol/L), the change of T-2 values display a good linear relationship with the concentration of Pb2+ from 40 mu mol/L to 100 mu mol/L and from 130 mu mol/L to 200 mu mol/L, respectively. Owing to the especially strong interaction between DHCA and Pb2+, DHCA-Fe/Fe3O4 NPs exhibited a high selectivity over other metal ions. (C) 2016 Chinese Chemical Society and Institute of Materia Medica, Chinese Academy of Medical Sciences. Published by Elsevier B.V. All rights reserved.