Development of an ultrasensitive colorimetric detection method of Cr2O72- ions with a colorimetric sensor based on gold nano flower particles

Abstract

A simple and facile colorimetric method for the detection of dichromate ions (Cr2O72？) using flower-shape gold nanoparticles (AuNFs) has been developed. Herein, a novel approach method was developed, based on the measurement of localized surface plasmon resonance absorption. Addition of Cr2O72？ ions selectively induced the aggregation of flower-shape gold nanoparticles, which resulted in red-shifted absorption accompanied by a color change from magenta purple to pale blue. The binding site and sensing mechanism for Cr2O72？ ions flower-shape gold nanoparticles were characterized by Fourier Transform infrared spectroscopy, ultraviolet-visible spectroscopy, and transmission electron microscopy. The optimized detection of Cr2O72？ via the flower-shape gold nanoparticle-based probe occurred at pH 4.0 and 30 ？C. The absorption ratios (A800 nm/A575 nm) were proportional to the Cr2O72？ concentrations within the range 0.0 μM？1.1 μM, with a detection limit of 3.03 nM in tap and pond water, respectively. The highly selective and sensitive colorimetric assay reported herein has been successfully applied to monitor the Cr2O72？ ion concentrations in spiked tap water, pond water samples. This sensing system allows rapid and facile determination of Cr2O72？ ions in various types of mineral supplement, and environmental samples.