Highly Sensitive Colorimetric Detection of the Toxic Metal Cadmium in Rice Using the 3-(1h-Tetrazol-5-Yl) Aniline@Aunps Sensor

Abstract

A very poisonous heavy metal Cd2+ not only contaminates the living environment but also constitutes a serious menace to human health through water intake and food chains. Thus, monitoring and controlling the content of Cd2+ with rapidity, sensitivity, and simplicity in tap water, soil, and rice samples is important especially. In the work, a high-efficiency sensor based on gold nanoparticles (AuNPs) embellished and refined with 3-(1H-Tetrazol-5-yl) aniline (TAA) for the colorimetric detection of Cd2+ is rationally put forward. The chelation between Cd2+ and TAA@AuNPs is characterized using various test means including UV-visible spectroscopy, dynamic light scattering (DLS), Fourier transforms infrared (FTIR), Transmission electron microscopy (TEM) and analyzed by Gaussian16w and Multiwfn simulations. The interaction between Cd2+ and TAA@AuNPs leads to the agglomeration of the AuNPs solutions, resulting in the color of the system changing from wine-red to gray-blue. This color change can be easily captured by the naked eye, making it a visually perceivable detection method. The limit of detection (LOD) of the sensor is 1.0 μM when observe with the unaided eye, and UV-vis spectroscopy also has a LOD of 31 nM with an excellent linear relationship (R2 = 0.99049) in the concentration range of 0.0 ~ 8.0μM for Cd2+, indicating that AuNPs modified with TAA can be effectively used for the quantitative determination of Cd2+. Furthermore, the colorimetric sensor has been tested on tap water, soil, and rice samples, and it shows promising potential for the practical monitoring of harmful Cd2+ in environmental systems.

Keywords: AuNPs, Colorimetric detection, 3-(1H-Tetrazol-5-yl) aniline, Cd2+, Rice, Gaussian