Article review: Mercury Nanosensor uses DNA

Ming, L.; Wang, Q.; Shi, X.; Hornak, L. A.; Wu, N. Detection of Mercury (11) by Quantum Dot/ DNA/ Gold Nanoparticle Ensemble Based Nanosensor Via Nanometal Surface Energy Transfer. Analytical Chemistry 2011, 83, 7061-7065
https://pubs.acs.org/doi/abs/10.1021/ac2019014

In this article, Ming et al. describe the use of fluorescence spectroscopy to detect mercury [Hg(Il)] in both buffer and environmental samples. In order to do this, both a Quantum Dot and gold (Au) nanoparticle are functionalized with complimentary DNA strands with only one mismatch, a T-T pairing. When these two pieces are in solution without Hg(II), the quantum dot and the Au nanoparticle do not interact, which allows for the quantum dot to fluoresce. However, should Hg(II) be present, the Hg(II) will bind between the T-T mismatch, thereby bringing the quantum dot and the Au nanoparticle together and the fluorescence is quenched.

It was seen that as the amount of Hg(II) increased, less and less fluorescence was observed, as was expected. Additionally, it was found that there was high selectivity for Hg(II) as opposed to other environmental contaminants, such as Cu(II) and even Hg(I). A detection I limit was found for the both the buffer and environmental samples to be 0.4 and 1.2 ppb/g respectively.

This method has many potential uses for environmental testing. It is able to detect very small amounts of Hg(II) in water samples and can be employed for in the field testing, should the instrumentation be available. It would be interesting to see if different nanoparticles and quantum dots could be used to detect some other environmental contaminants via fluorescence, because fluorescence spectroscopy is a very sensitive technique that can produce rapid results, which may be important in the event of a catastrophe, if water quality measurements need to be made.