MIT’s DNA sensor detects HPV or HIV for less than a dollar

Scientists at the Massachusetts Institute of Technology (MIT) have succeeded in developing a robust disposable DNA sensor that can detect human papilloma and HI viruses. The application is very simple and can be carried out at home. The production costs of a sensor are around 50 US cents.

Electrochemical sensors detect diseases through changes in current when a target molecule interacts with an enzyme. The problem with such sensors is that they are not particularly durable without refrigeration and can therefore only be used in laboratories and surgeries, but not at home. This is because these sensors use a DNA-cleaving enzyme from the CRISPR gene editing system (Clustered Regularly Interspaced Short Palindromic Repeats), whose DNA coating breaks down quickly and therefore needs to be cooled.

The electrochemical sensor from MIT uses a strip of gold leaf coated with DNA and laminated to plastic, as shown in the study “Polymer Coating for the Long-Term Storage of Immobilized DNA” published in ACS Sensors. The DNA is anchored by the sulphur-based molecule thiol. The researchers have protected the DNA coating with an inexpensive polymer layer made of polyvinyl alcohol (PVA) so that it lasts for up to two months even at high temperatures of up to 65 °C. Due to its longer shelf life, the sensor can therefore also be used for self-diagnosis at home.

For self-diagnosis at home

The electrochemical sensor detects genetic material from viruses such as human papillomavirus (HPV) and HIV using a programmable guide RNA. This is linked to Cas12. This is an enzyme that is related to CRISPR’s Cas9. If the target molecule is present, Cas12 becomes active and cleaves the surrounding DNA, including the DNA strands on the sensor. The splitting changes an electrical signal that can be read using a device called a potentiostat. This allows the presence of the target gene to be confirmed or not confirmed.

The test is easy to use. It is sufficient to apply saliva or nasal swabs to the sensor, for example, to detect HPV or HIV. Other new infectious diseases can also be detected with adapted sensors, the MIT researchers write.

The sensors are already ready for use. MIT now wants to deliver them to test subjects for a broad field test via the MIT start-up delta v. They will then test the sensors under real conditions at home. Due to the shelf life of the sensors, they can be shipped without a cold chain.

(olb)