Colorimetric Sensing of Pb2+ Ion by Using Ag Nanoparticles in the Presence of Dithizone

Abstract

Colorimetric analysis of heavy metal ions can be realized by the aid of Ag nanoparticles to improve the analytical characteristics. The method is based on the localized surface plasmon resonance (LSPR) properties of the Ag nanoparticles (AgNPs). In this work, we applied the AgNPs with the addition of dithizone to further improve the selectivity and sensitivity of Pb2+ analysis. Colorimetric sensing of Pb2+ ions based on the polyvinyl alcohol (PVA)-stabilized-colloidal AgNPs in the presence of dithizone is reported. A linear decrease in the AgNPs LSPR absorbance at 421 nm was observed along with the increase in the Pb2+ concentration in the range of 0.50–10 µg/L. The other ions give a minor change in the LSPR absorbance of colloidal AgNPs. The Pb2+ limit of detection, the limit of quantification, and sensitivity were found to be 0.64 ± 0.04 µg/L, 2.1 ± 0.15 µg/L, 0.0282 ± 0.0040 L/µg (n = 5), respectively. The obtained sensitivity is comparable with that of the immunosensing method. The proposed method could offer a good alternative for colorimetric analysis of Pb2+ ions by using nanoparticles in the presence of ligands, which can improve selectivity.

Silver Nanoparticles as Colorimetric Sensors for Water Pollutants

“…The nanospheres, highly symmetrical particles, are the most studied because of their monodispersity and synthetic reproducibility, that assure the repeatability of experiments and results. Spherical AgNPs and their composites have a widely application range, mostly in biotechnology and sensors [79][80][81]85,95,96]. The AgNPs show a typical localized surface plasmon resonance (LSPR) whereby the electrons on the AgNPs surface interact with electromagnetic radiation, generating LSPR and producing extinction and scattering spectra, with absorption bands in the 370-470 nm range.…”

“…On the other hand, the void area has been used to tune the refractive index, increase the active region for catalysis, and advance the ability to tolerate cyclic volume modifications. The morphology plays a key role, especially for the possibility of having materials with different symmetries (spheres, AgNPs, cubes AgNCs) [79][80][81][82][83][84][85][86][87] or without defined and reproducible symmetry (stars, AgNSs, flower, AgNFs, wires, AgNWs) [69,[88][89][90][91][92][93][94]. TEM images of silver nanoparticles of different geometries and shape are presented in Figure 4.…”

Silver Nanoparticles for Water Pollution Monitoring and Treatments: Ecosafety Challenge and Cellulose-Based Hybrids Solution

“…By choosing the appropriate method and experimental parameters for the synthesis it is possible to control shapes and obtain spheres (AgNPhs), cubes (AgNCs), stars (AgNSs) and rods (AgNRs) [ 72 , 73 , 74 , 75 , 76 , 77 , 78 , 79 , 80 , 81 , 82 , 83 , 84 , 85 , 86 , 87 , 88 , 89 , 90 , 91 , 92 , 93 , 94 , 95 , 96 , 97 , 98 , 99 , 100 ]. Some examples with TEM images showing AgNPs with different geometries and shapes are presented in Figure 1 [ 68 , 81 , 88 ].…”

“…Among other shapes, the spherical one is the most symmetrical and is the most used because of the easy synthetic control of reproducibility and monodispersity, both being key aspects for ensuring the repeatability of experiments and results. The AgNPhs are synthesized by Turchevich and Shiffrin Brust methods and their modifications, producing the typical LSPR in the range 370–470 nm [ 26 , 54 , 72 , 73 , 74 , 75 , 76 , 77 ]. The well-assessed synthetic studies make it possible to also introduce these silver nanomaterials in nanocomposites, finding application above all in biotechnology and as sensors [ 55 , 74 , 78 , 79 ].…”

“…In fact, by changing the type of surface functionalization and by choosing a specific ligand, it is possible to make particles selective to a particular analyte, and by optimizing the degree of surface functionalization, their sensitivity can be improved. The main chemical molecules and capping agents used for direct functionalization of AgNPs during the synthesis of different morphologies are reported in Table 1 , together with dimension and applications for water pollution monitoring [ 26 , 54 , 72 , 73 , 74 , 76 , 77 , 78 , 79 , 80 , 81 , 82 , 83 , 84 , 85 , 86 , 87 , 88 , 101 , 102 , 103 , 104 , 105 , 106 , 107 , 108 ].…”