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

Abstract A magnetic sensor for detection of Pb 2+ has been developed based on Fe/Fe 3 O 4 nanoparticles modified by 3-(3,4-dihydroxyphenyl)propionic acid (DHCA). The carboxyl groups of DHCA have a strong affinity to coordination behavior of Pb 2+ thus inducing the transformation of Fe/Fe 3 O 4 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 Pb 2+ to an aq. solution of DHCA functionalized Fe/Fe 3 O 4 nanoparticles (DHCA-Fe/Fe 3 O 4 NPs) ([Fe] = 90 μmol/L), the change of T 2 values display a good linear relationship with the concentration of Pb 2+ from 40 μmol/L to 100 μmol/L and from 130 μmol/L to 200 μmol/L, respectively. Owing to the especially strong interaction between DHCA and Pb 2+ , DHCA-Fe/Fe 3 O 4 NPs exhibited a high selectivity over other metal ions.