On-site, rapid and visual method for nanomolar Hg²⁺ detection based on the thymine–Hg²⁺–thymine triggered “double” aggregation of Au nanoparticles enhancing the Tyndall effect

Abstract

A new equipment-free colorimetric nanosensor was initially developed for quantitative point-of-need detection of nanomolar Hg2+ ions based on the enhancement in Tyndall effect of Au nanoparticles via their target-triggered “double” aggregation.

Captivating nano sensors for mercury detection: a promising approach for monitoring of toxic mercury in environmental samples

“…Additionally, using a smartphone to do portable TE measurement makes it easier to quantitatively detect Hg( ii ) ions throughout a linear concentration range of 156 to 2500 nM, with a LOD of 25 nM. 78 Hsin-Yun Chang et al devised a fluorescent sensor labeled as BSA@R6G/MPA-Au NP via introducing bovine serum albumin (BSA) to a solution of AuNPs containing rhodamine 6G (R6G) and 3-mercaptopropionic acid (MPA) as depicted in Scheme 3 . BSA used to protect R6G/MPA-AuNPs from settled aggregation in high salt concentration.…”

Recent Advances in the Application of Bionanosensors for the Analysis of Heavy Metals in Aquatic Environments

“…A red laser pointer (635 nm) is used to induce the TE reaction, visible TE changes alone can be used to perform a qualitative or semi-quantitative examination of Hg 2+ levels in the sample. The TEA approach requires only a low-cost laser pointer for the operator to achieve qualitative visual examination of 625 nm Hg 2+ in less than 10 min [ 125 ].…”

“…( c ) Schematic representation of the novel TEA method with the bare AuNPs for the colorimetric detection of Hg 2+ ions based on the specific T-Hg 2+ -T coordination chemistry. Transmission electron microscope (TEM) images and their average gray (AG) values measured [ 125 ]. Reprinted with permission [ 125 ].…”

“…Transmission electron microscope (TEM) images and their average gray (AG) values measured [ 125 ]. Reprinted with permission [ 125 ]. Copyright 2021, RSC advances.…”

Analyte-triggered in situ “off–on” of Tyndall effect for smartphone-based quantitative nanosensing of Ag+ ions

“…To address the two issues, our group has recently adopted the Tyndall effect (TE) of the AuNPs and AgNPs as alternative colorimetric signaling to design enhanced visual methods where a smartphone is used for portable, equipment-free quantitative readout [26][27][28][29]. The TE, which is named for the 19th-century British physicist John Tyndall, generally refers to a visible light path in a colloid after the involved colloidal nanoparticles scatter a light beam [30][31][32][33].…”