According to the Centers for Disease Control and Prevention, Down syndrome is the most common birth defect, occurring once in every 700 births. However, traditional non-invasive prenatal tests for the condition are unreliable or carry risks for the mother and fetus. Now, researchers have developed a sensitive new biosensor that could someday be used to detect fetal Down syndrome DNA in pregnant women’s blood. They report their results in the ACS journal Nano Letters.
blood test is a laboratory analysis perform on a blood sample that is usually extracted from a vein in the arm using a hypodermic needle, or via finger prick. Multiple tests for specific blood components, such as a glucose test or a cholesterol test, are often grouped together into one test panel called a blood panel or blood work.
Pregnant women can have ultrasound
Blood tests are often use in health care to determine physiological and biochemical states, such as disease, mineral content, pharmaceutical drug effectiveness, and organ function. Typical clinical blood panels include a basic metabolic panel or a complete blood count. Blood tests are also use in drug tests to detect drug abuse. In some of the United States, a blood test is require before marriage.
Characterize by variable degrees of intellectual and developmental problems; so Down syndrome is cause by the presence of an extra copy of chromosome 21. To screen for 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; so 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 it is a slow and expensive process. Zhiyong Zhang and colleagues want to develop a fast; so sensitive and cost-effective test that could detect elevate DNA concentrations of chromosome 21 DNA in pregnant women’s blood.
Immobilize probe DNA
The researchers use field-effect transistor biosensor chips base on a single layer of molybdenum disulfide. They attached gold nanoparticles to the surface. On the nanoparticles, they immobilize probe DNA sequences that can recognize a specific sequence from chromosome 21. When the team add chromosome 21 DNA fragments to the sensor; hence they bound to the probes, causing a drop in the electrical current of the device.
The biosensor could detect DNA concentrations as low as 0.1 fM/L; which is much more sensitive than other report field-effect transistor DNA sensors. The researchers say that eventually; so the test be use to compare levels of chromosome 21 DNA in blood with that of another chromosome; such as 13, to determine if there are extra copies; suggesting a fetus has Down syndrome.