Sensor made of crushed graphene
DNA sensors based on graphene have been created
Researchers at the University of Illinois at Urbana-Champaign have for the first time created graphene-based biosensors that can detect the DNA of cancer cells in a patient's blood. The authors reported on the development in the journal Nature Communications (Hwang et al., Ultrasensitive detection of nucleic acids using deformed graphene channel field effect biosensors).
"Our new sensor can detect ultra–low concentrations of molecules that are markers of the disease, which is important for their early diagnosis," said Rashid Bashir, the head of the study, professor of bioengineering at the University of Illinois. "It is very sensitive, inexpensive, easy to use and uses graphene properties in a new way."
Graphene– a layer of graphite one atom thick, is a popular inexpensive material for electronic sensors. However, the nucleic acid sensors developed so far require amplification – isolation of a fragment of DNA or RNA and repeated copying of it in a test tube. This process is very long and can lead to errors.
Therefore, the authors of the new work decided to increase the detecting ability of graphene to such an extent that it could be used for analysis without preliminary DNA amplification. However, instead of using traditional methods of modifying the surface of this material, which scientists used earlier to improve its electronic properties, the researchers created a thin sheet of plastic, stretched it, put graphene, and then removed the voltage from the plastic sheet. Because of this, graphene shrank and its surface became crumpled.
Then the scientists tested the ability of the new sensor to perceive DNA and cancer-related microRNA both in buffer solution and in undiluted human blood serum and saw that its performance improved tens of thousands of times compared to flat graphene. According to the authors, they managed to obtain the highest sensitivity ever obtained with the electrical detection of biomolecules.
To determine the reason for this increase in sensor power, the research team used computer simulations to study the electrical properties of crumpled graphene and how DNA physically interacts with the sensor surface. They found that cavities in graphene serve as a trap for attracting and retaining DNA and RNA molecules. In addition, deformations occurred in the material, which changed its electrical properties (in particular, the width of the band gap), creating an energy barrier for electrons passing through it. This made it more sensitive to electric charges on nucleic acid molecules.
Portal "Eternal youth" http://vechnayamolodost.ru