Researchers at the University of Illinois at Chicago have shown that by interfacing brain cells onto graphene, they can differentiate a single hyperactive cancerous cell from a normal cell, pointing the way to developing a simple, noninvasive tool for early cancer diagnosis. This system is able to detect the level of activity of an interfaced cell, according to Vikas Berry, associate professor and head of chemical engineering at UIC. Berry led the research along with Ankit Mehta, assistant professor of clinical neurosurgery in the UIC College of Medicine.
Graphene is very sensitive to whatever happens on its surface and is the thinnest known material. The nanomaterial is composed of a single layer of carbon atoms that are linked in a hexagonal chicken-wire pattern. All of the atoms share a cloud of electron that move freely about the surface. Berry also said that the cell’s interface with graphene then rearranges the charge distribution in the graphene and modifies the energy of atomic vibration as detected by Raman spectroscopy. She refers this to a powerful workhorse technique that is routinely used to study graphene.
The atomic vibration energy in graphene’s crystal lattice does differ, depending on whether it’s in contact with a cancer cell or a normal cell. This is because the cancer cell’s hyperactivity leads to a higher negative charge on its surface and the release of more protons.
The electrons in graphene’s electron cloud are pushed away by the electric field around the cell. This changes the vibration energy of the carbon atoms. Raman mapping with a resolution of 300 nanometers, allowing characterization of the activity of a single cell, can pinpoint this change.
The journal ACS Applied Materials & Interfaces published the report that looked at cultured human brain cells, compared normal astrocytes to their cancerous counterpart and the highly malignant brain tumor glioblastoma multiforme. They are now studying the technique in a mouse model of cancer with results that look very promising. Down the road the experiments would be with patient biopsies.
They could use this technique to see if the tumor relapses once a patient has brain tumor surgery. They would need a cell sample that they could interface with graphene and look to see if cancer cells are still present. This same technique might also work to differentiate between other types of cells or the activity of cells.
They may be able to use it with bacteria to see if the strain is Gram-positive or Gram-negative and might be able to use it to detect sickle cells. Berry and other coworkers introduced nanoscale ripples in graphene earlier this year causing it to conduct differently in perpendicular directions, useful for electronics. The graphene was wrinkled by draping it over a string of rod-shaped bacteria and vacuum-shrinking the germs.
The earlier work was essentially flipped over so that instead of laying graphene on cells, they laid cells on graphene and studied graphene’s atomic vibrations.
Co-authors on the study are Bijentimala Keisham and Phong Nguyen of UIC chemical engineering and Arron Cole of UIC neurosurgery.
Dr Fredda Branyon