Valerie Sheares Ashby got to where she is today by being new.

“It’s great being new in an area, because you can do things that nobody else who knew any better would try. And they’ll work. I love being new.”

In spring of 2003, when she moved her lab from Iowa State back home to UNC — only fifty miles from her hometown of Clayton — Ashby wasn’t just choosing between corn and tobacco; she was itching for change. So to be hip with the times and place, she ventured into a hot new territory: biomaterials. The chemistry remained the same, but the rules had to change. “We now have to look at materials that are FDA-approved, biocompatible, and biodegradable,” she says. And there aren’t very many on the market — yet.

Ashby discovers, designs, and synthesizes new bioelastomers — soft materials which can be incorporated into human tissue. She encountered them by accident while finding new ways to combine the long chains of molecules that we call polyesters. Typically, materials that are FDA-approved for health purposes, from joint replacement to drug delivery, are crystalline and rigid, providing little flexibility or malleability. On the other hand, bioelastomers are very…well, elastic. Anything doctors put into patients’ bodies, Ashby maintains, should possess mechanical properties that allow it to mimic the tissue that’s around it, because doing so reduces scarring, irritation, and other incompatibility issues.

Click to read photo caption. Image by David Olson, ©2007 Endeavors magazine.

An elastomer’s network of cross-linked polymers makes it flexible and strong. Imagine a spiderweb, with each ring of silk connected to the adjacent ones by smaller silk segments. The greater the number of these small links, the tighter and more durable the web; if the web were to have fewer, it might be flimsy and collapse. And without the links, the web would have no shape at all. Elastomers behave the same way, except instead of silk rings, straight-chain polymers are connected to one another via cross-links, or covalent bonds.

Before Ashby’s investigation, bioelastomers generally fell into one of two categories: thermoplastic or thermoset materials. Thermoplastics are easy to prepare and manipulate, but many of them are crystalline — likely to swell, but not break down in the body. These materials can remain in a person’s body anywhere from six months to several years. Thermoset materials don’t have those drawbacks but are tedious and difficult to make, and they do not allow for easy variation of the number of cross-links.

Ashby’s research group has discovered a hybrid that combines all the useful characteristics of these two bioelastomers. Their method involves using a simple reaction of commercially available ingredients — the kind of technique a student would learn during their first semester in Ashby’s organic chemistry course — and yet allows the team to control the number of cross-links and therefore the strength of the material. After synthesizing countless materials and investigating their mechanical properties, the group realized they had discovered several soft, biodegradable, malleable elastomers that could easily mimic human tissue.

Mentoring as a lifestyle

Joe DeSimone, professor of chemistry, was one of Ashby’s mentors. He asked her what she wanted to do. Not in the next five minutes. Not in the next five years. But what did she actually want to do? With her life? No one had ever asked her before. “I didn’t even care what he did,” she says. “He immediately bought into me.” Now, Ashby says that most of what she’s accomplished depended on the enthusiasm and encouragement she got from her mentors.

As an undergraduate studying chemistry at UNC, she knew she wanted to teach, but she didn’t know how to go about it. In 1988, the summer before her senior year, she met Henry Frierson and participated in the inaugural program that would come to be known as the Summer Pre-Graduate Research Education program (SPGRE). Frierson, professor of educational psychology and evaluation, instituted the program to encourage minority students to go to graduate school. “The typical undergraduate student who has academic talent and research aptitude is not encouraged to pursue a Ph.D.,” Frierson says. “Instead, there’s more focus on traditional careers such as law, medicine, or business. I see this program as a possible avenue for students to gain opportunities that they ordinarily would not have received.” (See “cultivating new scientists”.)

With encouragement from Frierson and SPGRE, Ashby went to work on a doctorate in chemistry with DeSimone, then a young professor who was unpacking his boxes. Two internships, a doctoral degree, a post doc, and fifteen years later, Ashby still credits DeSimone with some of her forward momentum as a polymer chemist.

In DeSimone’s lab, Ashby found a culture that valued diversity — in people and ideas. “There’s no more fertile ground for innovation than to have diversity of experience around the table,” DeSimone says. He recalls giving a lecture to a small group of polymer chemists in Germany in the early 1990s. “Not only were they all white men, but they were all white men that had graduated from the same group over the last thirty years. So they all knew the same stuff. It really reinforced to me how important diversity of thought is.”

Shaping a new generation

In the classroom, Ashby cultivates that diversity by focusing on individual students. While she claims that teaching is just in her blood, her students say she works hard at it. “She knows all of her students’ names,” says Benjamin Pierce, a fourth-year graduate student in Ashby’s lab. “She prints out seven or eight pages of faces and names and studies them. And she’ll get them.” This fall she’s teaching introductory chemistry, and with about four hundred students, it’s one of the largest classes at UNC. But Pierce doesn’t doubt she’ll know even their pets’ names by the end of the semester. She makes herself available, adds Andy Brown, a third-year graduate student, to talk to anyone, about anything, anywhere.

Brown says Ashby’s patience and adaptability have enabled her research group to rack up ten patents, a host of publications, and collaborations with DuPont, 3M, and Chevron Phillips. “It seems like some advisors have their style set, and it’s dependent on the student to interpret and work around that,” Brown says. “But she works around you.”

Rising above adversity?

When some people think of successful African American women, they think of Oprah. Or The Color Purple. Or Oprah in The Color Purple. An underprivileged female rises above adversity despite opposition from every front. Ashby says that’s not her story. But she knows that the path generally hasn’t been easy for many other women and minorities in science. In the year 2000, fewer than 3 percent of graduate students earning their doctorates in a scientific field were African American women. Ashby wants to change that. She’s active in programs that promote minority scholarship. Domonique Downing, a senior chemistry major who joined Ashby’s lab as an SPGRE student, was a 2006 finalist for a national undergraduate research award. Ashby first taught Downing, whom she calls “my child,” in an organic chemistry class during Downing’s sophomore year.

Ashby says, “My role in this is to say, ‘I appreciate that you are a minority, or a minority woman. So what? At the end of the day, you need to get your work done.’”

Danielle Jacobs was a student who formerly contributed to Endeavors.

Valerie Ashby is an associate professor of chemistry in the College of Arts and Sciences. She is a 2006 Bowman and Gordon Gray awardee for outstanding achievement in teaching.