In the presence of MTase, a methyl group attaches to the molecular beacon, breaking it and causing it to fluoresce. The other oligonucleotide – called the primer – then reacts with the now-shortened molecular beacon in such a way that starts a chain reaction that amplifies the fluorescence signal.
The system performs three functions in one: substrate, template and reporter. The substrate detects MTase, the template rebuilds the substrate after it breaks, and the reporter fluoresces to indicate the presence of MTase. Dr Kong compares this to a smartphone, which performs the functions of camera, phone, calculator and more, whereas previously you would have had to carry all these items with you separately. "We’re trying to simplify the processes contained in the traditional analytical method", he says, "making things more efficient, more convenient, and low cost".
The sensor has an exceptionally low limit of detection, believed to be the lowest ever for a sensor of this kind. This enhanced sensitivity makes it possible to detect MTase abnormalities even when they are present in tiny amounts.
Dr Kong says that the dean of the college where he’s based has a motto: "We have a long time, but the patients do not." "These words always encourage us to work hard and speed up on the way to build clinical platforms", he says.
This article is free to read in our open access, flagship journal Chemical Science: Yun-Xi Cui et al., Chem. Sci., 2019, Advance Article. DOI: 10.1039/C8SC05102J. You can access our 2018 ChemSci Picks in this article collection. Read more like this