Evaluation of Silver Nanoparticles Stabilized with Sulfurized Ligands as Mercury (Hg II) Sensors in Water Samples

Abstract

In recent decades, Silver nanoparticles (SNPs) have attracted significant attention from the scientific community due to their distinctive property of localized surface Plasma resonance observed by Ultraviolet–visible spectroscopy. This relatively simple technique does not require sophisticated or instrumentation. Nanoparticles (NPs), unlike common dyes, have better stability, selectivity and viability characteristics to be very versatile, which allows these nanoparticles to be used as quite sensitive colorimetric sensors for the detection of Hg (II) ion, being able to form amalgams or aggregate. The proposed work aimed to prepare and evaluate colorimetric sensors based on SNPs for detecting mercury Hg (II ) in water and to synthesize SNPs and characterize them using UV-Vis spectrophotometry. The protocol for synthesizing spherical SNPs was standardized by the modified process of the Creighton method. SNPs with an average diameter of 30±2 nm were obtained according to the characterization by analysis of the TEM images. A functionalization protocol for SNPs with cysteamine (Cy) and cysteine ligands for detecting Hg (II) ions in water was implemented and optimized. A protocol for quantifying Hg (II) ions in water by UV-Vis spectrophotometry was established and optimized for each sensor under study. It was possible to obtain a detection limit of 109 nm for the SNPs-CyNH2 sensor with an incubation time of 2 min and a detection limit of 445 nm the SNPs-Cy sensor with an incubation Of 20 min The sensor-based on SNPs-CyNH2 presents good selectivity for most of the interfering ions studied.