Genetics and Health

Quantum Dot DNA Sensor

by Hsien Hsien Lei, PhD on December 7th, 2005

Scientists at Johns Hopkins have developed a new method for detecting mutations that is “ultrasensitive, quick and relatively simple.” It can be used to detect specific DNA sequences, genetic defects, and mutations. Using quantum dots made of semiconductor materials just a few nanometers wide, researchers have been able to detect a critical mutation linked to ovarian cancer.

Here’s how it works:

1. Two biological probes are made out of synthetic DNA. Each probe can find and capture the target DNA.
2. Attached to one probe is a Cy5 molecule that glows when it receives energy.
3. Attached to the other probe is biotin which sticks to streptavidin that coats the surface of the quantum dot.
4. The two DNA probes and a quantum dot are combined.
5. The DNA and quantum dot complex is exposed to the DNA to be analyzed.
6. If the target DNA sequence is present, the two DNA probes will sandwich it between them.
7. Biotin is then activated adhering the DNA “sandwich” to the quantum dot.
8. To make the quantum dot glow, a laser is shined on the quantum dot, DNA probe, and target DNA mixture.
9. The quantum dot passes the energy from the laser on to the Cy5 molecule attached on one of the probes ONLY IF the probes are attached to the target DNA.
10. If the target DNA sequence is present, the glow can be detected with a microscope.

Makes me nostalgic for the thousands of PCR beads I used in the lab while working on my doctoral dissertation.

Science Daily, December 6, 2005

Share This

Related Stories

DNA Origami
Deepak Chopra Still Having Trouble with Genes
Electronic structure of DNA revealed - may lead to easier sequencing of DNA
DNA Stereotyping

POSTED IN: Genetic Ingenuity