Could nanomaterials hold the answer to reversing the effects of UV radiation?
By Sherrie Negrea
The link between sunlight and skin cancer is widely accepted — the absorption of ultraviolet radiation can damage skin cells. Exactly how the sun’s radiation breaks down the DNA within cells is a process that Changhong Ke, assistant professor of mechanical engineering, has spent the past six years trying to understand.
At first, Ke used an atomic force microscope with an extremely sharp tip to observe the single- or double-strand breaks that radiation causes in DNA molecules. More recently he has collaborated with Jie (Jayne) Wu, associate professor of electrical and computer engineering at the University of Tennessee, to use an electrical field to separate the DNA based on the impairment it has experienced.
“This can help us understand the damage caused by the radiation, and it can be used to study the repair of DNA,” Ke says. “You have to know how much damage occurred before you even consider repairing the DNA.”
Ke’s research on detecting DNA damage is one example of how he has integrated biology and physics with mechanical engineering at the nano level. While he is conducting foundational research, Ke says the tools he has developed to observe DNA molecules could be applied to evaluate new therapeutic drugs designed to rebuild impaired cells.
“Our tools can help determine how efficient the drug is,” Ke says. “If 50 percent of a cell’s DNA has been damaged and, after drug treatment, only 20 percent of the total DNA is still damaged, then the drug has fixed 60 percent of the damaged DNA.”
After earning a bachelor’s degree at Beijing Institute of Technology, Ke completed a doctoral degree in mechanical engineering at Northwestern University, where he focused on nanomechanics. It wasn’t until he began a post-doctoral fellowship at Duke University that he delved into biophysics, the study of the physical properties of biomolecular structures.
At Duke, Ke was part of a team of scientists who were the first to measure the force between the nucleotides in a single-stranded DNA molecule with an atomic force microscope. By quantifying a single strand of DNA, the Duke scientists could separate the effects of the two principal forces that characterize the double helix structures — the stacking force between base units along the length of the helix and the pairing force between opposing base units that form its rungs.
After arriving at Binghamton in 2007, Ke began a new area of research with many potential applications — nanotubes. These hollow structures form low-density, high-strength materials that can be used for tasks ranging from drug delivery to spacecraft development. When thousands of nanotubes are joined together, they’re still thinner than a single strand of hair.
In 2010, Ke was one of 43 researchers nationwide selected for the Air Force’s Young Investigator Research Program, which supports scientists and engineers who have received a PhD in the past five years and who show exceptional ability and promise for conducting basic research. With a grant of $120,000 annually for three years, Ke is investigating whether nanotubes, formed from either carbon or boron nitride, could enable the Air Force to reduce the weight of vehicles such as fighter planes and spacecraft.
In another angle of this research, Ke is combining the carbon nanotubes with DNA molecules to create a hybrid material that may have therapeutic applications. Working with Assistant Professor of Mechanical Engineering Pong-Yu “Peter” Huang, Ke is attempting to determine how strong the bond is between the DNA and the nanotubes and, conversely, how much force is required to separate the two materials after they interact. That question will have a bearing on potential applications because once the DNA wraps around these nanotubes, the DNA can no longer perform its chemical functions and is rendered useless.
“If you use these as some sort of drug delivery agents for gene therapy, you want to know exactly what kinds of impact they have when these carbon nanotubes are injected into cells,” says Huang, who has been collaborating with Ke since 2010.
In his nanomechanics laboratory, Ke works with three graduate and two undergraduate students, often conducting research late into the night. One of his students, Meng Zheng, who received his PhD in mechanical engineering in May 2012, has published nine journal articles with Ke and given four presentations at national and international conferences.
What impressed Zheng in the four years he worked for Ke was his dedication and his attitude toward his research. “I learned a lot from his research skills — how to define a problem, how to analyze a problem and how to solve a problem,” Zheng says. “He’s also a kind-hearted person and he can motivate people. He’s the best professor I’ve had in my life.”