play vital role in laser research
Oct. 9, 2001
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.
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.
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
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
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
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."
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."
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."
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.
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."
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."
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 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.
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.
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.
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."
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.
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."
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."
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.
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.
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
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."
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
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."