Colorimetric Assay for Lead Ions Based on the Leaching of Gold Nanoparticles

Abstract

A colorimetric, label-free, and nonaggregation-based gold nanoparticles (Au NPs) probe has been developed for the detection of Pb(2+) in aqueous solution, based on the fact that Pb(2+) ions accelerate the leaching rate of Au NPs by thiosulfate (S(2)O(3)(2-)) and 2-mercaptoethanol (2-ME). Au NPs reacted with S(2)O(3)(2-) ions in solution to form Au(S(2)O(3))(2)(3-) complexes on the Au NP surfaces, leading to slight decreases in their surface plasmon resonance (SPR) absorption. Surface-assisted laser desorption/ionization time-of-flight ionization mass spectrometry (SALDI-TOF MS) data reveals the formation of Pb-Au alloys on the surfaces of the Au NPs in the presence of Pb(2+) ions and 2-ME. The formation of Pb-Au alloys accelerated the Au NPs rapidly dissolved into solution, leading to dramatic decreases in the SPR absorption. The 2-ME/S(2)O(3)(2-)-Au NP probe is highly sensitive (LOD = 0.5 nM) and selective (by at least 1000-fold over other metal ions) toward Pb(2+) ions, with a linear detection range (2.5 nM-10 muM) over nearly 4 orders of magnitude. The cost-effective probe allows rapid and simple determination of the concentrations of Pb(2+) ions in environmental samples (Montana soil and river), with results showing its great practicality for the detection of lead in real samples.

Colorimetric sensing of copper(II) based on catalytic etching of gold nanoparticles

“…The strategy is relatively simple but suffers from low sensitivity and selectivity. The third one was accomplished by the target induced or target catalyzed etching of AuNPs [22][23][24][25][26][27]. Such a method is promising due to its simplicity and excellent performance.…”

Colorimetric assay of lead using unmodified gold nanorods

“…Once introduced into the body, Pb 2+ is a potential neurotoxin that can cause chronic inflammation of the kidney and heart, inhibit brain development, and decrease nerve conduction velocity [1][2][3]. The maximum level of lead in drinking water permitted by the US Environmental Protection Agency is 15 μg/L (∼72 nM) [4,5]. These environmental and health problems of Pb 2+ have prompted researchers to develop efficient methods for selective and sensitive assay of the heavy metal ion to understand its distribution and pollution potential.…”

Colorimetric determination of copper ions based on the catalytic leaching of silver from the shell of silver-coated gold nanorods

“…It would be an excellent idea that using this dramatic color change caused by the different silver shell thickness to develop a colorimetric method. Herein, we designed a kind of Au@Ag NR-based platform for labelfree colorimetric determination of Cu )-Ag leaching system, which had been applied for extraction of Ag from minerals for many years [29][30][31][32]. In the presence of Cu 2+ , the catalytic leaching system induced obvious decreasing of thickness of the Ag shell and resulted in a red-shift concomitantly with a bright red-tobluish green color change.…”