Sensor detects Down syndrome DNA with blood tests during pregnancy

According to de Centers for Disease Control and Prevention, Down Syndrome is the most common birth defect, occurring once every 700 births. However, traditional non-invasive prenatal test for the condition are unreliable or carry risks to the mother and and fetus.

Researchers have now developed a sensitive new biosensor that could one day be used to detect fetal Down syndrome DNA in the blood of pregnant women. They report their results in ACS 'Nano Letters magazine.

Characterized by highly variable intellectual and developmental difficulties, Down syndrome is caused by the presence of an extra copy of chromosome 21.

To detect the condition, pregnant women can have ultrasound scans or indirect blood biomarker tests, but misdiagnosis rates are high. Amniocentesis, in which doctors insert a needle into the uterus to collect amniotic fluid, provides a definitive diagnosis, but the procedure poses risks to both the pregnant woman and the fetus.  

The emerging method of whole genome sequencing is highly accurate, but time consuming and expensive. Zhiyong Zhang and his colleagues wanted to develop a rapid, sensitive, and cost-effective test that could detect high concentrations of DNA from chromosome 21 DNA in the blood of pregnant women.

The researchers used field-effect transistor biosensor chips based on a single layer of molybdenum disulfide. They attached gold nanoparticles to the surface. On the nanoparticles, they immobilized probe DNA sequences that can recognize a specific sequence on chromosome 21.

When the team added DNA fragments from chromosome 21 to the sensor, they bonded to the probes, causing a drop in the device's electrical current. The biosensor could detect DNA concentrations as low as 0.1 fM / L, which is much more sensitive than other reported field-effect transistor DNA sensors. The researchers say that eventually, the test could be used to compare the DNA levels of chromosome 21 in the blood with that of another chromosome, such as 13, to determine if there are extra copies, suggesting that a fetus has Down syndrome.

Source

American Chemical Society

Materials provided by the American Chemical Society. Note: Content can be edited for style and length. Journal reference:
Jingxia Liu, Xihua Chen, Qinqin Wang, Mengmeng Xiao, Donglai Zhong, Wei Sun, Guangyu Zhang, Zhiyong Zhang. DNA sensors based on ultra-sensitive monolayer MoS2 field effect transistors for the detection of Down syndrome. Nano Letters, 2019; DOI: 10.1021 / acs.nanolett.8b03818