Ask the Experts: David Rovnyak on the NMR and undergraduate research
March 08, 2012
LEWISBURG, Pa. — David Rovnyak, associate professor of chemistry, describes the University's NMR imager and its role in undergraduate research. || Related link: Faculty profile
Q: Bucknell's students and faculty have access to a powerful piece of instrumentation - a 600 MHz nuclear magnetic resonance (NMR) imager. What is nuclear magnetic resonance, and why is it important?
A: Magnetic resonance is a property involving the nucleus of an atom. Think of the nucleus of an atom as being a tiny bell ringing with a characteristic note. With NMR, we detect that note for each atom, and that gives us rich information on the molecule the atom is a part of.
NMR touches on many people's lives at one point or another. Many of us have heard of things like magnetic resonance imaging, or MRI — and that's just the tip of the iceberg. Magnetic resonance is widely used from detecting landmines to enabling the drug discovery process. The chemical industry broadly depends on it. It's even being introduced into the security screening process.
Q: Is NMR dangerous?
A: No. The word "nuclear" sometimes raises public fears, but it refers to the nucleus of an atom. There's no radioactivity involved in the process. In fact, one of the reasons the technology is so widespread is that it's not dangerous.
Q: Is it common for a primarily undergraduate, liberal arts university like Bucknell to have this technology?
A: It's extremely unusual for an undergraduate institution to have an instrument this powerful. The American Chemical Society requires that every chemistry department operate an NMR spectrometer — that's how critical it is to the work that we do — but we're one of only three or four undergraduate institutions in the nation that offers NMR technology of this caliber.
Q: How and why did Bucknell acquire the 600 MHz NMR?
A: Back in 2004, a team of five Bucknell faculty members were awarded a major National Science Foundation grant to acquire a high-grade NMR with extra channels and extra capabilities, such as being able to test solids. With additional support from Bucknell's offices of the president, provost and department of chemistry, we acquired a fabulous instrument with a magnetic field about 250,000 times stronger than the earth's.
Bucknell has an unusually broad expertise in NMR. A few examples within the chemistry department are Professor Stockland who uses NMR to study metals in inorganic compounds and Professor Tillman who uses it to study polymers. In chemical engineering, Professor Maneval uses it to study engineering materials. In physics, Professor Ligare uses NMR to study novel ways to stimulate transitions between quantum states of oriented nuclei. We are always reaching out to collaborate with members of the University and region. The instrument should serve us for the next 20 or 30 years.
Q: Your research team has recently had a couple of breakthroughs. Can you describe those?
A: We had a very big break last year. We solved a problem that's been unsolved for more than 20 years relating to a fundamental question of how the NMR signal — this ringing of the bell — is acquired. There's a limit to how much signal can be gotten out of a sample, and there are relatively few techniques out there to enhance the signal. We've shown how to enhance the signal by factors of two, three and sometimes even four and five.
We published a paper last year with two student co-authors on this work, and we submitted a major follow-up paper this week involving a large collaborative network with a number of laboratories on the East Coast. That paper also includes a Bucknell student co-author. We're excited to see where this goes. We're really gratified by the attention we've received for solving this problem.
Q: And the other breakthrough?
A: Professor of Chemistry Timothy Strein and I have been studying molecular aggregates called micelles. We study a particular kind of micelle that occurs in our bodies.
Bile micelles have been poorly understood for about 50 years, especially with regard to something called a critical micelle concentration. In other words, how many of these molecules do you have to put into a flask in order to get them to form an aggregate?
We've made observations lately that we think bring together views that researchers thought were contradictory. We realized that micelles were forming aggregates in two separate stages, and some labs were observing the second stage and other labs were observing the first stage. So we've been able to show that instead of being contradictory both views are correct. For the first time, we've also seen how small molecules insert structurally into the interior of micelles.
We're really looking forwarding to writing about our work and sharing it. The high-field NMR has been crucial to give us enough sensitivity and resolution to be able to observe molecular details on that scale.
Q: What are some of the potential applications of your new understanding of micelles?
A: It is very common in the lab to need to isolate components of a mixture. With expertise found in the Strein lab, bile micelles can be used to do that; some of the things we've learned may make it possible separate these components more completely. || Related link: Rovnyak lab
We're also curious to see whether what we've learned has any relevance in physiological processes. We're looking to see whether this new knowledge will inform our understanding of how bile micelles work in the body. There are a vast number of questions about how bile micelles are participating more broadly in biochemistry. For instance, there are medical studies that show that bile micelles in some cases accelerate and in some cases inhibit specific cancers. It's extremely complicated to try to unravel how bile micelles are affecting some of these cancers. We hope that we've made some fundamental discoveries that could be the basis for tackling these difficult questions.
Interviewed by Molly O'Brien-Foelsch
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