Synthesis, detection, and modification of the surface of gold nanorods and their optical sensitivity for low concentrations of iron (III) ions

Mahsa Mohammadzadeh and Mohsen Ashjari

Abstract

In this paper, a nanosensor has been developed to detect metal Fe3 + ions based on gold nanorods. The gold nanorods used in this research were synthesized using a modified seed-mediated growth method that minimizes the presence of spherical gold nanoparticles in the solution and, with controlled growth of nanorods, uniformly distributes them in the solution. Under reaction conditions, iron metal ions react with gold nanorods, resulting in a change in the structure of the nanoparticles and, consequently, their plasmonic properties. The detection of Fe³⁺ ions was carried out solely by the absorption mechanism and due to the changes in the longitudinal plasmon wavelength of the gold nanorods. One of the important achievements of this method is the detection limit of water-soluble Fe³⁺ ions, which is obtained at 0.1 ppm. The properties of gold nanorods and the interaction of Fe³⁺ ions with nanosensors were studied using a UV–vis spectrophotometer; FT-IR, XRD and transmission electron microscopy (TEM) spectroscopies were used to investigate the morphology and nature of synthetized gold nanorods. In this research, a new nanosensor was introduced to detect water-soluble Fe³⁺ ions at a concentration of parts per million (ppm), which could eliminate the need for complex chemical sensors and advanced expensive equipment, and provide a simple, low-cost and highly selective detection platform