Undergraduate research is a critical resource for established labs. Students with fresh ideas infuse new creativity into the questions researchers are attempting to answer. Christina Tang, Ph.D., associate professor of chemical and life science engineering, encourages students to get involved early in their academic careers.
“I use an apprentice-style model where undergraduates take primary responsibility for the research and to provide substantial input into its direction,” Tang said. “Undergraduate projects are open-ended, but smaller and more defined in scope to produce significant results within one academic year.”
Tang’s lab recently explored different collector plate implementations in order to create functional 2D and 3D shapes from a single-step electrospinning process. Undergraduate students Jocelyn Trapp, Ioana Caloian and Ryan A. Kim worked alongside Tang and her graduate students.
Electrospinning is an established technique for creating nanofibers and microfibers. The process uses an electric current applied to, for example, the needle of a syringe filled with a solution of nylon and formic acid. Electrostatic stress from the current overcomes the surface tension keeping the solution contained. A thin jet of material leaves the syringe and, as the solvent within the solution evaporates, the resultant fibers gather on a nearby surface.
Collector plates made of foil are typically used as the surface to gather nonwoven fibers (think of the fibers in paper towels or coffee filters) generated by electrospinning. Researchers experiment with different implementations of the collector plate and spinneret, the syringe-like device containing the nanofiber solution, to achieve specific results.
Tang’s research is part of a multidisciplinary team of arts, business and engineering faculty and students. The goal was to construct fibers using different methods and materials in a collaborative project between the VCU College of Engineering and VCU School of the Arts (VCUarts). Funding for the initiative was made possible, in part, through Tang’s National Science Foundation (NSF) CAREER award for Directed Self-Assembly of Multifunctional Polymer Nanoreactors for Sustainable Chemical Manufacturing.
Trapp joined the lab after completing a research experience for undergraduate program (REU) in pharmaceutical engineering with Tang.
“My experience with research started as part of the nanomaterials vertically integrated project (VIP) team with Dr. Wei-Ning Wang,” Trapp said. “I fell in love with the research process and, afterwards, I was able to participate in a summer REU at VCU, which led me to work with Dr.Tang’s lab.”
Kim asked to join Tang’s lab while taking his chemical engineering fundamentals class in 2019. He joined the smart fabrics VIP team the following year and worked with Tang until graduating in spring of 2022.
Caloian was taking the same chemical engineering fundamentals class in 2020 and joined Tang’s lab soon after. A former chemistry major, she was accepted into the Dean’s Undergraduate Research Initiative (DURI), a program designed to broaden the undergraduate student experience and provide opportunities for graduate students and postdoctoral fellows to develop skills in mentoring. Caloian then joined the smart fabrics VIP team.
“My VCU academic career began with chemistry after moving to the United States from Romania,” said Caloian. “Aspects of the chemistry major weren’t a good fit for me, so chemical engineering seemed logical to explore. Dr. Tang was a wonderful mentor, she helped me realize chemical engineering spans more than just the oil and pharmaceutical industries.”
In their experiments, Tang’s lab uses a charged mesh collector plate to control how fibers deposit themselves when the solution jet evaporates and nanofiber material is formed. Material gathers more densely around the mesh structure and not the gaps between, creating a template the fibers build around. Variations in the mesh size and electric charge influence the patterning and thickness of the nanofibers.
“With a foil collector, fibers are deposited randomly during the electrospinning process,” Tang said, “The charged mesh serves as a patterned conductive electrode, generating a locally-concentrated electric field that attracts electrospun fibers. This allows us to control the form and makeup of resultant material by modifying the mesh collector.”
VCUarts’ Department of Fashion Design and Merchandising collaborated with Tang’s lab to design the mesh collector plates. Among the 3D meshes created was a protective hood to shield the wearer from rain.
Adding to the effect different collector plate and spinneret implementations have on the final product, the nanofiber solution blend also plays an important role. Combinations of materials used to create the nanofiber can affect the resulting materials' flexural rigidity, the ability of the material to bend without breaking, and hydrophobicity, the ability of the material to repel liquids.
“For this experiment, we had already decided nylon would be the base of our solution,” Tang said, “It has good mechanical properties in addition to being hydrophobic. We also found the higher molecular weight of nylon led to thicker and more durable products.”
Creating disposable items like surgical masks or shoe covers for clean rooms on demand using electrospinning with an electrically-charged mesh is one application of this technology. Rapid fabrication like this can also be applied to filtration, tissue engineering, drug delivery and electronics.
Undergraduates Trapp, Kim and Caloian used this project to gain practical experience once their passion for research manifested.
An interest in nanomaterials formed a path to Tang’s lab for Trapp. It was important for her to gain an understanding of research by interacting with faculty and graduate students. It provided her the information necessary to pursue that career path.
Kim’s interest in research began with the Science Olympiad club at his high school in Loudoun County, Virginia. He chose VCU for its urban feel and close distance to home. The versatility of chemical and life science engineering and the positive impact the industry makes in the world is what attracted Kim to Tang’s research.
Chemical engineering seemed a natural evolution for Caloian, who began her undergraduate education as a chemistry major. The undergraduate research in Tang’s lab helped develop her interest in materials science.
Tang and her undergraduate researchers were supported by graduate researchers Melissa W. Williams and Mahmoud E. Moustafa. Their research findings were published in Polymers, a peer-reviewed, open access journal of polymer science.