Ultrasensitive colorimetric detection of manganese(Ⅱ) ions based on anti-aggregation of unmodified silver nanoparticles

摘要

We report a facile, selective, and sensitive colorimetric assay for Mn~(2+) ions based on the anti-aggregation of unmodified silver nanoparticles (AgNPs). In the absence of Mn~(2+) ions, the addition of L-arginine to the AgNPs dispersion caused the aggregation of AgNPs via Ag-N covalent interaction, and the color of the solution changed from yellow to colorless. While the presence of Mn~(2+) ions can prevent the aggregation of AgNPs due to the formation of the complex between Mn~(2+) ions and L-arginine, accompanying with a distinct color change from colorless to yellow with the increase of Mn~(2+) ions. Under the optimal experimental conditions, the absorbance at 390 nm was linearly proportional to the Mn~(2+) ions concentration in the ranges from 0 to 700 nM, and from 5 μM to 70 μM, with a detection limit of 20 nM. Also, it was successfully used for the detection of Mn~(2+) ions in environmental water samples.