By REGINA CARSON
At Roanoke Valley Governor’s School, students are charged each year with carrying out a science fair project.
Occasionally a student gets so interested in his work that it becomes a multi-year commitment, and that is what happened this year with Gavin Oxley, a Lord Botetourt High School senior working in the biomedical field. His project, titled “Effect of Silver Nanoparticles on Antibacterial and Mechanical Properties of a Copolymer,” won first place at the Governor’s School’s Student Project Forum on February 3, and will next compete at the regional fair on March 17.
Last year Oxley discovered the most effective concentration of a polyethylene oxide polymer to make the stitches surgeons use able to dissolve in water without losing any of their mechanical properties. He used that as a control for this year’s project, in which he hypothesized that incorporating silver nanoparticles into the concentration would give those water-soluble sutures antibacterial properties and added strength.
Why silver? “I think true innovation takes something and makes it better without increasing the cost,” said Oxley. “Silver nanoparticles have long been known for their ability to prevent disease and enhance technologies. They’re already in use in a lot of hospitals in one form or another, and they’re relatively inexpensive.”
Thanks to the Governor’s School’s recent investment in an atomic force microscope (AFM), Oxley was able to complete his entire nanoscale project in-house. He recreated the polymer from last year to use as his control, and he created two variants that contain silver, one with a high concentration of silver nanoparticles and one with a low concentration of silver nanoparticles. The AFM allowed Oxley to see the tiny nanoparticles he was working with – the prefix “nano” means “one-billionth” – and compare the topography of the concentrations.
Oxley performed three types of tests on each polymer. To test for antibacterial properties, Oxley grew Staphylococcus epidermidis bacterium atop each of the solidified polymers and documented the bacteria’s growth. To test for solubility, he took a sample of each polymer, determined its mass and thickness, and then recorded the length of time each one took to dissolve in water. For tensile strength, he took sample strips from the polymers, hooked them up to a tensile test machine, stretched them until they snapped, and measured newtons at the cross sections.
As often happens in science, Oxley’s results both supported and refuted his hypothesis.
“The low silver concentration increased the strength of the polymer by 75 percent,” he said, “but the high silver concentration actually weakened it. Solubility decreased as silver concentration increased, but that ended up being a good thing because the lower solubility lengthened the time the polymer could remain in tissue without dissolving, making it even more optimal for suturing. Early testing showed that bacterial growth decreased as silver concentration increased, which is what I predicted, but then I ran out of time! The research is promising, but I need more trials to fully conclude the concentration’s antibacterial effects.”
With fear of infection a perennial concern in the medical community, I asked Oxley where he got the idea for such a significant, relevant project. Chemistry class? A medical journal? An alert from the CDC? Oxley laughed. “It was from Grey’s Anatomy,” he said, smiling. “Season 10, Episode 8.”
Gavin Oxley is just one of the 262 gifted and talented young scientists who attend the Roanoke Valley Governor’s School for Science and Technology. To learn more about the Governor’s School, a half-day regional public STEM school for motivated students in grades nine through twelve, please visit the school’s website at www.rvgs.k12.va.us or contact the school’s director, Mark Levy, or the school’s guidance counselor, Kathy Sebolt, at 540.853.2116.