Students play vital role in laser research

By Julie Neumann
Oct. 9, 2001

On projects ranging from bone surgery to protein identification, students play a vital role in the life of Vanderbilt's Free-Electron Laser Center. Undergraduates like Arman Hakimian get an invaluable introduction to the world of research, while doctoral students like Michelle Baltz-Knorr hone their research skills and painstakingly construct the intellectual groundwork upon which their future scientific careers will be based.

The Undergraduate Student

Eyebrow ring, spiky hair, trendy clothes…not exactly your typical nerd attire. Then again twenty-year-old Arman Hakimian is not your typical science geek. He is getting the sort of hands-on research experience about which most nerds can only dream.

Last summer Hakimian worked on bone ablation with physics research associate Borslav Ivanov. The research focuses on using the free-electron laser (FEL) to break apart bone by dissociating its bonds. Not only does the FEL allow a surgeon to cut with extreme precision, but it also is ideal for the work because it can be tuned to frequencies where most of its energy is absorbed by the water molecules or proteins that are present in abundance within living bones. As a result, bone ablation done with the FEL requires less energy than saws or other lasers, greatly reducing the damage it does to surrounding tissue.

The opportunity to work at the FEL was a lucky break for Hakimian, who was not expecting to have such a fascinating summer job. "I wanted to do something different for a change over the summer," explained Hakimian. "Every single summer that I was a waiter I told myself that it would be the last summer. Then the next summer would come and it'd be the easiest thing to make the most money." But this spring he took the initiative to ask his physics professor and major advisor if they knew of any summer positions for undergraduates. "Three days before school was out I got an e-mail from Professor Haglund saying that, if I was still interested, there was a job at the FEL. I was absolutely ecstatic. I was about to give up, to just be a waiter again."

When Hakimian showed up for work, it quickly became apparent that the bone ablation research would be a perfect fit. "I am more interested in something that could be surgically applied since I hope to be a surgeon one day," noted the premed physics major. "This is more applicable to what I enjoy."

Instead of being put to work as the lab peon, Hakimian got to work on every aspect of the research. "Borslav and I are the only two that work on this. We are the ones that are hands on and do everything. We both set up the optics and cut specimens; I personally got the computer up and running."

Such responsibility was not always easy. He remembers his first experiences in the lab were like "pushing me out of a plane with no parachute." But he is quick to remark "sometimes that is the best way to learn. You are either interested or not. If you're not you'll quit, but if you are you'll learn."

Learning became a daily occurrence for Hakimian. The bone ablation research has required him to work in areas of physics that were new to him. Though he has never taken an optics class, for example, he estimates that he has acquired a working knowledge of the subject equivalent to having completed a semester-long course.

He has also discovered the nature of real-world research. "The first experiments we did were so rough. I was controlling the read-out on the monitor, pausing it and printing it because we didn't have it hooked up to a computer yet. Borslav was manually working the laser shutter, flipping the thing on and off," Hakimian recalls, shaking his head with disbelief. "I was very shocked because I saw so many problems. Everyone told me to calm down; they said 'This is how it works.' You take all the problems and keep going."

The end result is that Hakimian has come to love the work. "You can take it as a stressful job, but I think of it as more of a challenge. As long as you are doing all that you can, you'll come out on top in the end."

He hopes to be kept on throughout the remainder of the project. Having been involved since nearly the beginning, he has watched the research evolve from scratch. He intends to squeeze in lab time between classes so that he can continue his involvement.

The Doctoral Student

Across the hall from Hakimian, Michelle Baltz-Knorr is in her third year of research at the FEL. The two labs appear to be mirror images of each other, the standard thick blue pipes of the laser rising distinctly from a mess of wires and metal. Despite the nearly identical environment, however, Baltz-Knorr's work is dramatically different. She devotes her time to running experiments designed to determine how best to utilize laser light to identify proteins, the molecular machinery essential to life.

Currently, one of the leading methods for identifying proteins is a technique called matrix-assisted laser desorption ionization (MALDI) . It is a form of mass spectrometry that utilizes a laser beam to separate proteins from a matrix and then ionize them so their mass can be measured with a high level of precision. Mixing proteins with matrix material is a complicated and time-consuming process. Also, a number of matrix materials are organic acids that can chemically attack protein molecules; drying the matrix into tiny crystallites also changes the delicate conformation of the proteins. But the matrix material is necessary because irradiating pure protein samples with high-power lasers breaks up most of the proteins rather than desorbing them. So researchers must add specific matrix materials to make the method work with the fixed-frequency lasers that they have available. This creates something of a Catch 22: The scientists want to identify a given protein, but to do so they must add agents that can alter the very molecules they are attempting to identify.

Baltz-Knorr hopes to change all that with the help of the FEL. The fact that the FEL beam can be tuned anywhere from 2 to 10 microns in wavelength greatly expands the universe of possible matrix materials beyond those that work with conventional lasers. This has allowed the doctoral student and her colleagues to explore novel matrix materials such as electrophoresis gel and, most notably, biologically relevant compounds including water.

"If you think about your body and you think about your cells, how much organic acid do you have in there?" Baltz-Knorr asks wryly. "Hopefully not a lot." With human cells being made up of nearly 80% water, the ability to perform mass spectrometry directly from water samples should have dramatic implications for genetics and medical research. "The end product," she explains, "is to study proteins directly from cells."

In addition to water, Baltz-Knorr has also worked with polyacrylamide gel, which is widely used in gel electrophoresis. By demonstrating that the gel itself can be used as the matrix, she has laid the ground work for a faster and more cost-effective method for identifying proteins than those currently in use.

"Having the FEL has allowed us to take more biologically relevant matrices such as polyacrylamide or water and ask, 'What wavelength would work? What can we do to not alter the sample?'" Explains Baltz-Knorr, "Most people have to say, 'This is the laser I have: What sample can I use to make it work? What processes do I need to go through?' With the free-electron laser, we can ask 'How should we adjust the laser wavelength and pulse duration to get the optimum yield of the proteins we are looking for?' The results are very exciting."

Three years of research have led to this point. Baltz-Knorr has spent five years at Vanderbilt as a doctoral student, two of those years under a molecular biophysics training grant funded by the National Institutes of Health. "I came in as undecided physics but was interested in biological physics. My advisor, Richard Haglund, encouraged me to apply for the grant, which pulls students from all disciplines…," she pauses. "But I had no bio background except for biology and anatomy in high school."

So Baltz-Knorr had to start from scratch in biochemistry, spending the summers catching up and relying on the sympathy of helpful professors. After the first year she was hooked, having developed a passionate interest in understanding the workings of the body at the molecular level. Soon after, she was brought into the IR-MALDI group at the FEL in hopes that she could apply her newfound knowledge.

Immediately the selection and treatment of matrix material caught Baltz-Knorr's interest. "I started saying to Richard, 'Why not look at different matrices, these acids aren't in your cells, it's not natural.'" The team started on glycerol but quickly moved on to explore more biologically relevant matrices. The FEL's variable wavelength pushed them in the direction of polyacrylamide and water.

After several long months of working out kinks in the equipment, Baltz-Knorr was finally able to put her ideas to the test. "The first time I saw a signal from polyacrylamide gel I just about did cartwheels around the room. It's just this feeling of, 'Oh it worked! Thank God.'"

"[When] you can produce signals that no one else has ever produced before, it's an incredible feeling. Especially when you look at it and know that this could have huge applications in the real world, that people could actually use this in the medical field."

She has remained passionate ever since. The work has certainly been challenging, but for Baltz-Knorr that is part of the fun. "Sometimes what we see is a puzzle... we have to work backwards and try to find the mechanisms and processes behind what's happening. Even when you don't necessarily understand what you are seeing and why you are seeing it, it's important. You know it will help you down the road."

The mass spectrometry research has been a slow but focused process, much like Baltz-Knorr's own growth as a physicist. "When you are starting out, you aren't sure if this is way you want to go and you are just trying to find your way, which can be a little daunting. I was very lucky that I had a great advisor that encouraged me to think up my own project and find something I wanted to do."