New Sensor Electrically Detects Genetic Mutations

A new graphene chip that detects a single nucleotide mutation in DNA molecules is a first step toward implantable and portable wireless biosensors that could provide early warning of cancer or other diseases, researchers at the Univ. of California, San Diego (UCSD) say.

The chip uses a method called DNA strand displacement to detect single nucleotide polymorphisms (SNPs), variations of one single building block in a DNA or RNA sequence. Some SNPs are associated with increased risk of developing cancer and other disorders. Using the new chip, the researchers were able to detect a single nucleotide change in a 47-nucleotide-long string of DNA.

“It doesn’t require an expensive laser scanner or lab-scale setting,” says Michael Hwang, a doctoral student in materials science at UCSD. In fact, because the chip uses changes in an electrical signal to detect the mutation, the signal can be sent wirelessly to a desktop computer or even to a smartphone.

“The portability and cost-efficiency of this technology make it highly promising for a broad range of global health and disease management applications,” says Ratneshwar Lal, a UCSD bioengineer.

Currently, researchers detect SNPs either with enzyme-based methods, which are accurate but expensive, or with hybridization-based methods and optical sensing. The hybridization-based methods involve designing single-strand DNA probes with a single SNP present. If the target DNA contains the same SNP, then that target DNA will bond to the DNA probe. Typically, fluorescent...