New metal biosensing technology developed

A new litmus test for uncovering potential gold and other metals has been developed to support geochemical exploration.

Associate professor at the University of Nebraska – Lincoln, Rebecca Lai, has developed metal detecting biosensor to aid the gold exploration industry, according to Science Daily.

She is also creating biosensors to detect mercury, silver, and platinum.

"Geochemical exploration for gold is becoming increasingly important to the mining industry," Lai said.

"There is a need for developing sensitive, selective and cost-effective analytical methods capable of identifying and quantifying gold in complex biological and environmental samples."

The technology, used on paper strips about the size of a litmus strip is a portable, reusable alternative to existing methods and is built from long observed reactions between metal ions and the building blocks of life – DNA.

As different metals have different interactions DNA’s components – adenine, cytosine, guanine, and thymine – the biosensors can be used to identify which metals are present in the samples.

The research focuses on oligoadenines (short for adenine chains) and their use in measuring concentrations of the target metals in water samples, as well as their presence.

"Although these interactions have been well-studied, they have not been exploited for use in electrochemical metal ion sensing," Lai and doctoral student Yao Wu explained in Analytical Chemistry.

In terms of gold, the DNA based sensor detects a gold ion that originates from the dissolution of metallic gold, and measures electric current passing from an electrode to a tracer molecule – in this case methylene blue.

If no gold is detected then the measured current is high.

However if gold is detected then the flexibility of the oligoadenine DAN probes in hampered, causing a reduction in the current from the tracer molecule.

The size and type of current change is then used to determine the concentration of gold in the sample.

The sensor can be reused after this by removing the gold via application of another ligand.

"The detected Au(III) has to come from metallic gold, so if gold is found in a water supply, a gold deposit is somewhere nearby," Lai sad.

However, “the DNA-based biosensors need more refinement before they can be made commercially viable.”



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