Engineering team recognized for breakthrough antimicrobial research

Published: Jun 19, 2008 10:30:29 AM
Media Contact: Sally Credille, src0007@auburn.edu, 334.844.3447

Antimicrobial coating process

Faculty member Aleksandr Simonian displays a slide sample dipped and coated as part of the process in creating their antimicrobial coatings.

A team of researchers from the Samuel Ginn College of Engineering has produced antimicrobial coatings that have the potential to prevent diseases from spreading on contaminated surfaces. This is a growing problem not only in hospitals but also in schools, offices, airplanes and elsewhere.

Led by Virginia Davis, assistant professor in the Department of Chemical Engineering, and Aleksandr Simonian, professor of materials engineering in the Department of Mechanical Engineering, the Auburn researchers mixed solutions of lysozyme, a natural product with antimicrobial properties found in egg whites and human tears, with single-walled carbon nanotubes (SWNTs). Similar to a rolled sheet of graphite, SWNTs, at one nanometer in diameter, are a perfect cylinder of carbon.

Davis, Nepal, Balasubramanian, Simonian

(From left to right) Faculty member Virginia Davis, postdoctoral student Dhriti Nepal, graduate student Shankar Balasubramanian and faculty member Aleksandr Simonian discuss future uses and applications for their coatings.

"Lysozyme is used in some commercial products such as Biotene mouthwash," said Davis. "However, lysozyme itself is not as tough. Single-walled carbon nanotubes, on the other hand, are among the strongest materials known to man. While they are 100 times as strong as steel, they have only one-sixth the weight."

By using a process called layer-by-layer deposition, the team demonstrated the inability of intact Staphylococcus aureus cells to grow on antimicrobial surfaces.

"Disinfection generally requires rigorous cleaning with solvent that must remain wet for a given period of time to insure that surface germs are killed," said Davis. "In contrast, we have created a surface that is inherently antimicrobial, so how long it is wet is not an issue."

Virginia Davis

Virginia Davis, assistant professor in the Department of Chemical Engineering, led the team of researchers at the Samuel Ginn College of Engineering in developing antimicrobial coatings made from a combination of the natural enzyme lysozyme and single-walled carbon nanotubes.

Davis' research paper, "Strong Antimicrobial Coatings: Single-Walled Carbon Nanotubes Armored with Biopolymers," was recently featured in NanoLetters, a premier journal in the field, frequently cited by top researchers.

"The material presented in NanoLetters is only the beginning," said Davis. "We plan to adapt processing to enable the assembly of coatings on a much larger scale. As a foundation for future applications, the combination of single-walled carbon nanotubes with DNA, proteins and enzymes enables a range of possibilities for sensing and smart-functionality capabilities."

Davis' research and teaching expertise is related to SWNTs, their dispersion and shear alignment, which involves nanotube exploitation of specific properties and alignment across large spaces. She is a former student of Matteo Pasquali, associate professor of chemical and biomolecular engineering at Rice University, and Nobel Prize winner Richard E. Smalley. Simonian is a recognized expert in smart bio-functionalized materials and bio-sensing. He founded the biosensors laboratory at Yerevan Physics Institute in Armenia and serves as a member of the Auburn University Detection and Food Safety Center.

Graduate student Shankar Balasubramanian, whose expertise is in biosensors and antimicrobial materials, and postdoctoral student Dhriti Nepal, whose background is in SWNT-biopolymer dispersion contributed to the project.

Davis' paper can be read online at http://pubs.acs.org/cgi-bin/abstract.cgi/nalefd/asap/abs/nl080522t.html

For additional information related to research conducted in the Department of Chemical Engineering or the Samuel Ginn College of Engineering at Auburn University please visit http://eng.auburn.edu/.