Aaron Wheeler: Big ideas, little chips
Even when approached with a seemingly outlandish research idea, the one word that isn’t in analytical chemist Aaron Wheeler’s vocabulary is “no.” Instead, he might be skeptical, says Mais Jebrail, one of Wheeler’s PhD students, but he’ll say, “Try it out and convince me.”
Wheeler has used his expertise in microfluidics to explore applications far beyond the separation and chemical analysis of droplets on tiny chips. At his University of Toronto laboratory, Wheeler and his team have used mazes made from miniscule channels to probe the learning capabilities of C. elegans1 and measured hormone levels from just a microliter of breast tissue.
As a chemistry undergraduate at Furman University in South Carolina, Wheeler wanted to work on life science problems and even considered medical school. But, in 1996, an analytical chemistry course forged a link between his love of instruments and optics and his fascination with biomedicine.
As a PhD student at Stanford University, Wheeler plunged into the emerging technology of microfluidics, using the technology to analyze the chemical contents of a single cell.2 He rapidly became enamored with the accessibility of working with microfluidic chips. “It is so visual—just a pen and a piece of paper are all that it takes” to dream up a cartoon to solve a particular problem, Wheeler says. But turning that vision into a reality requires troubleshooting myriad miniature plumbing problems: dust, bubbles, and fluids flowing in unexpected ways.
“He brought this passion for trying to get something to work and the ability to persevere in the face of great difficulty,” says Stanford chemist Richard Zare, Wheeler’s PhD adviser. “I could tell that he was going to become a great researcher.”
After an interdisciplinary postdoc at UCLA, where he was mentored by chemist Robin Garrell and collaborated with mechanical engineer Chang-Jin Kim and biochemist Joseph Loo, Wheeler moved to Toronto in 2005. Wheeler fosters a collaborative atmosphere among the chemists, engineers, and life scientists that make up his group and with researchers across the university, says Noha Mousa, a University of Toronto PhD student who collaborates with Wheeler.
Mousa recently teamed up with Wheeler to study anti-estrogen treatments in breast cancer using digital microfluidic chips, which use an array of controllable electrodes instead of miniscule channels and pits to direct and analyze liquids. Mousa thought that the new technology—Wheeler’s is one of a handful of labs using digital microfluidics—might allow her to measure hormone levels in breast tissue less invasively, avoiding traditional biopsies that can require up to a gram of tissue.
In early 2008, Mousa approached Wheeler with a cartoon and a research plan and began working in his lab full time, collaborating with Jebrail to develop a microfluidic system that successfully extracted estradiol from one microliter of breast tissue, blood, and serum.3 “This is the most fun project thatac I’ve ever had in research,” Mousa says.
“[Science] really is a social enterprise,” Wheeler says. “And that’s one of the parts of this job that I love.
Position: Assistant Professor, Department of Chemistry, University of Toront
1. J. Qin, A.K. Wheeler, “Maze exploration and learning in C. elegans, ”Lab on a Chip, 7:186–92, 2007. (Cited in 12 papers)
2. H.K. Wu et al., “Chemical cytometry on a picoliter-scale integrated microfluidic chip,” PNAS, 101:12809–813, 2004. (Cited in 98 papers)
3. N.A. Mousa et al., “Droplet-scale estrogen assays in breast tissue, blood, and serum,” Sci Transl Med, 1: ra2, DOI:10.1126/scitranslmed.3000105, 2009.