“The ultimate goal is to make something similar to a hand-held glucose monitor for future genetic testing,” said researcher Joseph Wang. “The electronic detection of DNA is a thing of beauty. You can make it small, low-power, inexpensive and robust, creating all sorts of advantages.”

Wang and colleagues used nanocrystals of zinc sulphide, cadmium sulphide, lead sulphide and copper sulphide. They linked each type of nanocrystal to mononucleotides containing a specific base - to adenine (A), cytosine (C), guanine (G) and thymine (T), respectively. The DNA bases A and T combine together to form complementary base pairs, as do the bases C and G.

Next, the researchers introduced each type of these monobase-conjugated nanocrystals in turn into a solution of mismatch-containing hybrids captured on magnetic beads. This caused the nanocrystals to bind via base-pairing to different complementary mismatched sites, as well as to previously linked monobase-conjugated nanocrystals.

As a result, each of the eight types of single-base mismatch captured different nanocrystal-mononucleotide conjugates. For example, the T-G mutation captured A-ZnS and C-CdS, which then base-paired to T-CuS and G-PbS respectively. This gave the mutation a characteristic four-potential voltammogram.

The scientists expect the other seven mutations to have different voltammetric signatures. That means this bioelectronic coding will enable identification of mutations in a single voltammetric run.

“The novelty of the approach is the combination of the nanocrystal tagging of DNA to create electro-diverse signatures and combining them with a fast, portable, low-cost electronic detection,” said Wang.

The technique can detect SNPs in as little as two hours - much faster than current methods. What’s more, it does not require heating above room temperature. The scientists say the method is also readily adaptable for identifying protein targets or single molecules, enabling applications in detecting infectious agents and providing reliable forensic analysis.

The researchers reported their work in Journal of the American Chemical Society.