Recent Advances on the Development of Chemosensors for the Detection of Mercury Toxicity: A Review

Shiva Prasad Kollur,Charley A Cull,Sharanagouda S Patil,Chandan Shivamallu,Ravindra Veerapur,Raghavendra G Amachawadi,Johann F Coetzee,Shashanka K Prasad

doi:10.3390/separations8100192

Abstract

The harmful impact of mercury on biological systems is of great concern. Regardless of the efforts made by the regulating agencies, a decrease in Hg2+ concentration has not been realized, and hence mercury accumulation in the environment remains of utmost concern. Designing novel and efficient probes for recognition and detection of toxic metals in environmental samples has been of primary importance. Among the available techniques, probe designs involving the study of spectral properties has been preferred because of its obvious ease of instrumentation. Furthermore, occurrence of significant changes in the visible portion of electronic spectra enables detection by the naked eye, thereby endorsing the preference for development of probes with off-on binary responses to aid in the in-field sample analysis. The prominence is further streamlined to the use of fluorescence to help characterize on-response the cellular detection of Hg2+ with ease. In order to overcome the problem of developing efficient probes or sensors bearing fluorescence on-response mechanism that can work effectively in physiological conditions, various methodologies, such as chemo-dosimetric reaction mechanisms for the designing of new luminescent ligands, are being adopted. Additionally, modified charge transfer processes are also being considered for optical detection of the mercury (II) ion. In this review, all such possible techniques have been discussed in detail.

Highlights

Mercury, previously named hydrargyrum (Hg) and commonly called quicksilver, is a chemical element with the atomic number 80 and a relatively high atomic mass of 200.59 u
Research on fluorescence sensor capable of detecting the heavy and transition metal ions has gained attention due to significant progress in synthesis of novel fluorophores and the development of cost-effective yet efficient methods. Advantages such as high sensitivity, selectivity, short response time, naked-eye detection, and fluorescence detection have been regarded as promising candidates in the molecular recognition and current applications of chemosensors
Results from this study suggested that the binding of Hg2+ to dissolved organic matter (DOM; hydrophobic acids isolated from the Florida Everglades by XAD-8 resin) under ambient conditions is controlled by a small number of DOM molecules containing a highly reactive thiol functional group (Figure 13)

Summary

Introduction

Previously named hydrargyrum (Hg) and commonly called quicksilver, is a chemical element with the atomic number 80 and a relatively high atomic mass of 200.59 u. Colorimetric receptors were developed for the selective recognition of heavy metal ions that received attention for several decades due to their ability to permit naked eye detection of color change and simplify the whole method. Research on fluorescence sensor capable of detecting the heavy and transition metal ions has gained attention due to significant progress in synthesis of novel fluorophores and the development of cost-effective yet efficient methods. Advantages such as high sensitivity, selectivity, short response time, naked-eye detection, and fluorescence detection have been regarded as promising candidates in the molecular recognition and current applications of chemosensors. Internal electron transfer (ICT) is an alternate mechanism where a fraction of the electron charge is transferred between the molecular entities [20]

Mercury Chemosensors

Formation of Hg-C Bond

With Porphyrine Binding Group

Conclusions