Colorimetric detection of Fe~(3+) ions using pyrophosphate functionalized gold nanoparticles

摘要

A sensitive, selective colorimetric Fe~(3+) detection method has been developed by using pyrophosphate functionalized gold nanoparticles (P 2O74--AuNPs). Gold nanoparticles were prepared by reducing HAuCl_4 with sodium borohydride, in the presence of Na_4P_2O_7. IR spectra suggested that pyrophosphates were capped on the surface of the gold nanoparticles. Aggregation of P_2O_7~(4-)-AuNPs was induced immediately in the presence of Fe~(3+) ions, yielding a color change from pink to violet. This Fe~(3+)-induced aggregation of P_2O_7~(4-)-AuNPs was monitored using first the naked eye and then UV-vis spectroscopy with a detection limit of 5.6 μM. The P_2O _7~(4-)-AuNPs bound by Fe~(3+) showed excellent selectivity compared to other metal ions (Ca~(2+), Cd~(2+), Co~(2+), Fe~(2+), Hg~(2+), K~+, Mg ~(2+), Mn~(2+), Na~+, Ni~(2+), Pb ~(2+), and Zn~(2+)). The best detection of Fe~(3+) was achieved in a pH range from 3 to 9. In addition, the P_2O _7~(4-)-AuNPs were also used to detect Fe~(3+) in lake water samples, with low interference.