Rapid and high precision detection of toxic metal ions is one of the chief requirements today to combat environment pollution. Gold nanoparticles play a key role in this by assisting the development of smart sensors and detection agents. Their high surface to volume ratio and unique optical property facilitates the development of high sensitive analytical GNP based bio-sensing tools. Recently, a major research thrust area has been the design and development of smartly fabricated GNPs as probes for selective detection of toxic contaminates and metal pollutants. In this review we focus on the use of GNPs and its functionalization for colorimetric detection of metal ions. Colorimetric detection enables cost effective and simple monitoring of toxic ions accompanied with the advantages of on-site applicability, avoids complex instrumentation, ease of analysis and usage. We also discuss the promising prospects and future potentiality of GNPs to serve as next generation multi-functional sensing tools and “lab-on-chip” detection agents.

Gold nanoparticles as efficient sensors in colorimetric detection of toxic metal ions: A review

Microorganism remediation strategies towards heavy metals.

Plasmonic colorimetric sensors based on etching and growth of noble metal nanoparticles: Strategies and applications.

Nanomaterials based electrochemical sensor and biosensor platforms for environmental applications

A simple and low cost chemosensor is described. This sensor could simultaneously detect three biologically important metal ions through fluorogenic (Zn2+) and chromogenic (Fe2+, Cu2+, and Zn2+) methods in aqueous solution. The sensor could function as a “turn-on” fluorescence receptor only to Zn2+ ions. In addition, the sensor could be successfully applied to the detection of intracellular Zn2+. Meanwhile, the sensor displayed an obvious red color upon selective binding with Fe2+. Therefore, the sensor could serve as a useful tool for the discrimination of Fe2+ from Fe3+ in aqueous media. Moreover, the sensor also showed color changes from yellow to colorless upon selective binding with Zn2+ and Cu2+, respectively. The detection limit of the sensor for Cu2+ (1.5 μM) is far below the guidelines of the World Health Organization (30 μM) as the maximum allowable copper concentration in drinking water, and therefore it is capable of being a practical system for the monitoring of Cu2+ concentrations in aqueous samples. These results provide a new approach for selectively recognizing the most important three trace elements in the human body simultaneously, for Zn2+ by emission spectra and Fe2+, Cu2+, and Zn2+ by the naked eye.

A cap-type Schiff base acting as a fluorescence sensor for zinc(II) and a colorimetric sensor for iron(II), copper(II), and zinc(II) in aqueous media

As one of the most toxic heavy metals, mercury ion (Hg 2+ ) has become a concern focus for its severe threats to environment and human health. As a result, it is of great importance to develop novel methods to realize the recognition and quantification of Hg 2+ . The past decades witness the development of nanomaterial-based optical sensors for Hg 2+ detection, showing the benefits of simplicity, rapidity, high sensitivity and selectivity, and cost-effectiveness. The reported methods have allowed the detectability down to nanomolar concentrations or much lower levels, and proved their practical applications for detecting and quantifying Hg 2+ in synthetic solutions or natural water samples. In this review, we summarize the published innovations in nanomaterial-based optical sensors for the detection of Hg 2+ according to different sensing strategies, including colorimetric, fluorescent and surface enhanced Raman scattering detection. Moreover, some challenges and significant attempts related to these methods are also discussed.

http://ir.yic.ac.cn/bitstream/133337/17510/1/Nanomaterial-based%20optical%20sensors%20for%20mercury%20ions.pdf

Nanomaterial-based optical sensors for mercury ions

Here, we propose a plasmonic enzyme-linked immunosorbent assay (ELISA) based on highly sensitive colorimetric detection of alkaline phosphatase (ALP), which is achieved by iodine-mediated etching of gold nanorods (AuNRs). Once the sandwich-type immunocomplex is formed, the ALP bound on the polystyrene microwells will hydrolyze ascorbic acid 2-phosphate into ascorbic acid. Subsequently, iodate is reduced to iodine, a moderate oxidant, which etches AuNRs from rod to sphere in shape. The shape change of AuNRs leads to a blue-shift of longitudinal localized surface plasmon resonance. As a result, the solution of AuNRs changes from blue to red. Benefiting from the highly sensitive detection of ALP, the proposed plasmonic ELISA has achieved an ultralow detection limit (100 pg/mL) for human immunoglobulin G (IgG). Importantly, the visual detection limit (3.0 ng/mL) allows the rapid differential diagnosis with the naked eye. The further detection of human IgG in fetal bovine serum indicates its applicability to the determination of low abundance protein in complex biological samples.

http://ir.yic.ac.cn/bitstream/133337/9299/4/Iodine-Mediated%20Etching%20of%20Gold%20Nanorods%20for%20Plasmonic%20ELISA%20Based%20on%20Colorimetric%20Detection%20of%20Alkaline%20Phosphatase.pdf

Iodine-Mediated Etching of Gold Nanorods for Plasmonic ELISA Based on Colorimetric Detection of Alkaline Phosphatase.

http://ir.yic.ac.cn/bitstream/133337/6993/2/Colorimetric%20sensing%20of%20copper%28II%29%20based%20on%20catalytic%20etching%20of%20gold%20nanorods.pdf

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

/pdf/red-to-blue-colorimetric-detection-of-chromium-via-cr-iii-4v490iswbx.pdf

Red-to-blue colorimetric detection of chromium via Cr (III)-citrate chelating based on Tween 20-stabilized gold nanoparticles

We have described a simple and low-cost visual method for on-site detection of hydrogen sulfide (H2S) in air based on the antiaggregation of gold nanoparticles (AuNPs). The bubbling of H2S into a weak alkaline buffer solution leads to the formation of HS–, which can stabilize the AuNPs and ensure the AuNPs maintain their red color even in a Tris buffer solution containing 80 mM NaCl with the presence of Tween 80. The stabilization of the AuNPs is attributed to the adsorption of negatively charged S2– on the AuNPs surface. In contrast, without the bubbling of H2S, AuNPs aggregate and change color from red to blue. Under optimal conditions, the proposed method exhibits excellent visual sensitivity with a naked-eye detectable limit of 0.5 ppm (v/v), making the on-site detection of H2S possible. This method also possesses good selectivity toward H2S over other gases by using a simple SO2 removal device. The successful determination of the concentrations of H2S in local air indicates the potential application ...

/pdf/on-site-visual-detection-of-hydrogen-sulfide-in-air-based-on-73p4jv8cvu.pdf

Shasha Wang

Papers

Nanomaterial-based optical sensors for mercury ions

Iodine-Mediated Etching of Gold Nanorods for Plasmonic ELISA Based on Colorimetric Detection of Alkaline Phosphatase.

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

Red-to-blue colorimetric detection of chromium via Cr (III)-citrate chelating based on Tween 20-stabilized gold nanoparticles

On-Site Visual Detection of Hydrogen Sulfide in Air Based on Enhancing the Stability of Gold Nanoparticles