Colorimetric Signal Amplification Assay for Mercury Ions Based on the Catalysis of Gold Amalgam

Abstract

Mercury is a major threat to the environment and to human health. It is highly desirable to develop a user-friendly kit for on-site mercury detection. Such a method must be able to detect mercury below the threshold levels (10 nM) for drinking water defined by the U.S. Environmental Protection Agency. Herein, we for the first time reported catalytically active gold amalgam-based reaction between 4-nitrophenol and NaBH4 with colorimetric sensing function. We take advantage of the correlation between the catalytic properties and the surface area of gold amalgam, which is proportional to the amount of the gold nanoparticle (AuNP)-bound Hg(2+). As the concentration of Hg(2+) increases until the saturation of Hg onto the AuNPs, the catalytic performance of the gold amalgam is much stronger due to the formation of gold amalgam and the increase of the nanoparticle surface area, leading to the decrease of the reduction time of 4-nitrophenol for the color change. This sensing system exhibits excellent selectivity and ultrahigh sensitivity up to the 1.45 nM detection limit. The practical use of this system for Hg(2+) determination in tap water samples is also demonstrated successfully.

Enhancement of the Intrinsic Peroxidase-Like Activity of Graphitic Carbon Nitride Nanosheets by ssDNAs and Its Application for Detection of Exosomes

“…10 These advantageous features encourage extensive exploration of the applications of nanozymes in diverse areas including biosensing, imaging, and therapeutics over the past few decades. 11,12 However, it remains challenging to obtain nanozymes that enhance the catalytic activity, which greatly limits the scope and performance of their applications. 13–15 The typical approaches to promote the catalytic activity of nanozymes are to construct hybrid nanostructures or to combine the nanozymes with a natural enzyme.…”

Fluorescent Gold Clusters as Logic Gates for the Detection of Different Metal Ions

“…In this study, Au NCs facilitate the reduction of Hg 2+ via surface‐capped citrate. The amalgam formation also indicates citrate‐capped Au NCs . The QY of Au NCs is ~10 % ( n = 3).…”

“…The results show that the fluorescence of Fe 3+ and Cr 3+ can be recovered after adding EDTA. The fluorescence response of Au NCs with Hg 2+ (Figure ) could not be recovered because of the formation of an amalgam . It is known that the Au surface has strong affinity for Hg 2+ .…”

A Simple Paper-Based Colorimetric Device for Rapid Mercury(II) Assay

“…Recently, many works have discovered that mercury ions could interact with other metal nanoparticles to form bimetallic NPs4748. In addition, it was also confirmed that the citrate around the surface of metal NPs was essential to promote the process of these combinations.…”