Colorimetric Assay for Determination of Lead (II) Based on Its Incorporation into Gold Nanoparticles during Their Synthesis

Abstract

In this report, we present a new method for visual detection of Pb2+. Gold nanoparticles (Au-NPs) were synthesized in one step at room temperature, using gallic acid (GA) as reducer and stabilizer. Pb2+ is added during the gold nanoparticle formation. Analysis of Pb2+ is conducted by a dual strategy, namely, colorimetry and spectrometry. During Au-NPs synthesis, addition of Pb2+ would lead to formation of Pb-GA complex, which can induce the aggregation of newly-formed small unstable gold nanoclusters. Consequently, colorimetric detection of trace Pb2+ can be realized. As the Pb2+ concentration increases, the color turns from red-wine to purple, and finally blue. This method offers a sensitive linear correlation between the shift of the absorption band (Δλ) and logarithm of Pb2+ concentration ranging from 5.0 × 10−8 to 1.0 × 10−6 M with a linear fit coefficient of 0.998, and a high selectivity for Pb2+ detection with a low detection limit down to 2.5 × 10−8 M.

Controlled spontaneous generation of gold nanoparticles assisted by dual reducing and capping agents

“…Interesting findings were notably obtained with tannic acid [113,114], ascorbic acid [115], ascorbic-acid-based amphiphiles [116], gallic acid [117], 2-mercaptosuccinic acid [118,119], lactic acid [120], cinnamic acid [121], and the synthetic antibiotic ciprofloxacin (1-cyclopropyl-6-fluoro-1,4-dihydro-4-oxo-7-piperazinylquinolone-3-carboxylic acid) [122]. The main interest of these weak organic acids compared with some other reducing agents relies on the fact that Au-NPs can be synthesized at neutral pH and at room temperature.…”

Green synthesis of gold and silver nanoparticles using gallic acid: catalytic activity and conversion yield toward the 4-nitrophenol reduction reaction

“…In this work, gallic acid was utilized as both a reducing and stabilizing agent for synthesizing both GA-AuNPs and GAAgNPs. GA-AuNPs and GA-AgNPs have been synthesized by other researchers (Yoosaf et al 2007;Martinez-Castanon et al 2008;Ding et al 2010;Huang et al 2010;Moreno-Alvarez et al 2010;Su et al 2012). These researchers employed a green synthetic strategy in a one-step process in which gallic acid was utilized as both a reducing and stabilizing agent without using any other chemicals.…”

“…GA-AuNPs are primarily used for the selective colorimetric sensing of Pb 2? ions (Yoosaf et al 2007;MartinezCastanon et al 2008;Ding et al 2010;Huang et al 2010;Moreno-Alvarez et al 2010;Su et al 2012). Cyromazine, an insecticide, has also been selectively detected by GA-AuNPs with a detection limit of 0.07 lM in aqueous solution (Su et al 2012).…”

Optical paper-based sensor for ascorbic acid quantification using silver nanoparticles

“…Recent advances with these materials have allowed the development of robust, highly sensitive and selective detection methods that are envisaged to surpass some limitations of conventional detection procedures [3]. In this context, silver nanoparticles have been considered as promising and powerful tools for sensing and imaging applications due to their optical properties [4][5][6][7][8][9][10][11][12][13]. Thompson et al used oligonucleotide silver nanoparticle conjugates in a sandwich assay to detect a target oligonucleotide through colorimetric analysis to differentiate a single base mismatch with a lower concentration of a specific DNA sequence [14].…”