Mercury detection with gold nanorods

Mercury is harmful even in small amounts, but detecting it currently requires the use of expensive equipment. Now, researchers at Ireland’s University College Cork have discovered that tiny gold nanorods could be used to detect mercury with high sensitivity, making them potentially suitable for use as portable analysers that can perform a rapid analysis in the field.

Writing in the journal Science and Technology of Advanced Materials, the scientists detailed how they fixed an individual gold nanorod to a glass slide, which was placed under an electron microscope. Using an imaging method called dark-field microscopy, the team studied the composition of the sample by measuring how light scatters off the rod’s surface.

The gold nanorod typically produced a red wavelength pattern, but when it was dipped in a salty solution containing trace levels of mercury, the shape and composition of the rod changed, producing an orange wavelength pattern. The more mercury in the solution, the more the wavelength changed. The nanorods were found to be far more sensitive to mercury than to other metals, including lead, nickel, copper and magnesium.

The researchers acknowledged that hurdles do remain. The size and shape of gold nanorods vary from rod to rod, throwing off measurements, so manufacturers must improve their fabrication so they are consistent. Also, pre-purification protocols of the rods will be required before real-world analysis can be reliably performed. Nevertheless, the study authors believe their approach has the potential to be used for real sensing applications.

Image credit: ©FreeImages.com/grindean horea