A colorimetric method is described for the determination of ferrous ion (Fe2+) with high sensitivity and selectivity. The method is
based on catalytic etching of gold nanorod (NR). In an acid condition, Fe2+ reacts with H2O2 to produce superoxide radical (O2
•−)
that etches gold NRs from the low energy surface along the longitudinal direction preferentially. As a result, the changes in the
absorption spectrum and color of gold NR can be measured and also can be detected visually. Under the optimal conditions, the
assay has very low detection limit (13.5 nM) and a linear response in a concentration range of 75 to 1 μM. The method was
applied to the determination of Fe2+ in spiked samples of fetal bovine serum and also transferred to a kind of test stripe for use in
fast practical applications. A unique colorimetric sensing method is demonstrated for the colorimetric detection of Fe2+, again
based on the oxidation of gold nanorods which leads to the blue-shift of the absorption.

EB00000002729K

Available

• Colorimetric determination of ferrous ion via morphology transition of gold nanorods