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​Can scientists ‘magnetize’ defective DNA as a cancer detection tool?

​An international team has found a way to attach clusters of magnetic nanoparticles to DNA, then pick out cancer signals the way a computer reads data off a hard drive.

yellow illustration of DNA

Detecting dangerous DNA: the nano solution | Illustration by Stefani Billings

DNA is the body’s blueprint for making healthy cells and proteins, and many forms of cancer can occur when it is altered through, for instance, exposure to chemicals or radiation.

In some cases, it is a mutation to the DNA that redraws the blueprint in a cancer-causing way. In other instances, through a process known as epigenetic modification, the DNA is unaltered, but a chemical group gets added to the genetic code causing the body to misinterpret the blueprint.

Unfortunately, existing tests to detect these mutations and epigenetic modifications are costly, time-consuming and imprecise. But a Stanford-led research team has discovered a new way to identify certain type of cancers at a very early stage by using a sophisticated version of the sensor technology that is used to find specific data files on magnetic hard disk drives.

The technique, described in a recent paper in the journal ASC Nano, promises to be cheaper, faster and more accurate because of the way it uses magnetic nanoparticles to tag defective DNA, says Stanford engineer Shan X. Wang, who led the project along with Danish physicist Mikkel Hansen.

“We can do more experiments and test for more mutations and epigenetic modifications,” Wang said. “This is going to increase the pace of discovery.”

How it works

The new process depends on the fact that magnetic particles—billions of times smaller than the eye can see—attach themselves to DNA much the same as magnets can be attached to a refrigerator. However, unlike the refrigerator magnet, when researchers heated the DNA, the magnetic particles quickly fell off the normal—or “wild type,” to use the scientific term—DNA, but clung to altered, cancer-causing DNA.

Over months of experiments the researchers showed how they could use the same sort of sensors that find data on hard drives to spot the clusters of magnetic nanoparticles to identify the presence of potentially cancer-causing DNA.

Giovanni Rizzi, a postdoctoral fellow in the Department of Micro and Nanotechnology at the Technical University of Denmark, said the sensors can clearly detect the magnetic nanoparticles without being distracted by the biological “noise” of the cellular or genetic material that can interfere with other types of tests for DNA that has undergone mutation or epigenetic modification.

Cancer finder

Wang has used this procedure of tagging biomolecules with magnetic particles to experiment with other health-related issues, but the technique is particularly valuable for cancer detection because of the complexity of the disease. Cancer is rooted in the genes, and is driven by both mutation and epigenesis. As a general rule, the more mutations and epigenetic modifications present in DNA, the greater the chances for cancer to occur. There are always some bad copies of DNA floating around in an individual’s body, but thanks to the new technique researchers say they will eventually be able to quantify a patient’s cancer risk by identifying the prevalence of genomic anomalies that could lead to a malignancy.

In their ACS Nano paper, the researchers focused on melanoma. However, Wang and his collaborators believe the process should yield similar results for other forms of cancer. They are now designing larger studies that could be applied to a variety of malignancies.

Much work remains to be done to turn this experimental test procedure into a useful diagnostic device, but the researchers say their international collaboration is one way to speed things up. “We were working in Denmark on a comparable system, and it was clear we would all benefit by combining our resources,” Rizzi said. “Our partnership, the sharing of our technologies and ideas, made this success possible.”

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