Monitoring Mercury Levels with Gold Nanoparticles

Mercury is considered one of the top ten chemicals of major public health concern, and exposure to even small amounts can cause serious health problems. This issue is especially prevalent in developing nations.

Source: World Health Organization

Current Testing Methods

Current environmental testing methods include spectroscopic analysis and colorimetric analysis. Spectrometry has high sensitivity and selectivity, but requires expensive instrumentation with labor-intensive sample preparation. This makes field-analysis difficult and unpractical. On the other hand, colorimetric analysis is simple and low-cost requiring no sophisticated instruments. However, current colorimetric assays can suffer from nonspecific interactions with other metals and metal ions. In field analysis, sample matrices are often complex with many analytes that can greatly impact mercury readings. In response to the need for a more reliable, on-site mercury detection technology researchers have developed a nanoparticle mercury sensor that is highly sensitive, selective, and stable.

Table 1: Current Exposure Limits to Mercury to Avoid Health Problems, Illness, and Poising. Souce: ATSDR – Mercury – Regulations and Advisories

A New Nanoparticle Mercury Detector

The new technology relies on a novel system incorporating plasmonic gold nanoparticles (AuNPs), and only requires a visible spectrophotometer to read results. The detection assay is initially being developed to detect mercury in water. The true advance is the pairing of gold nanoparticles with M13 phages to greatly enhance selectivity.¹ While gold nanoparticles and mercury are naturally attracted to each other, alone gold suffers from interference from competing metallic ions. The researchers were able to successfully grow gold nanoparticles on the surface of M13 bacteriophages which served as a bio-template to create a AuNP-Phage network. The M13 phage acts as a double fail safe, since the phages themselves are highly selective binders of mercury, The combination of AuNPs and M13 phage greatly enhances mercury specific selectivity and was demonstrated to have a lower limit of detection of 8 x 10^-8 mol/L. This is roughly .016 ng/L (or 0.000000016 mg/L), and is 125,000 times less than the current EPA limit for drinking water.

With improved sensitivity, low cost, and no need for complicated instrumentation nanotechnology may provide a viable solution to reduce ongoing public health concerns about mercury poisoning.

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