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Anthony Turcios ’20 works on configuring a laser pulse shaping apparatus in Professor Michael Durst's Biomedical Optics Lab.

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Students Harness the Power of Light in Biomedical Optics Lab

April 9, 2018

MIDDLEBURY, Vt. – Hang out in one of Michael Durst’s physics classes for a little while and you’ll hear two key phrases: “Now you get to use all the math you’ve ever known” and “That’s a great question.”

Both underscore his love of physics and his love of teaching.

“I like seeing students discover physics,” said Durst, an assistant professor of physics. “I like to see them have that aha moment when they realize they have the tools to understand something that is complex. I think the liberal arts model is an excellent way to make physics approachable and welcoming. And I think it’s important for students to understand what research is.”

Anthony Turcios ’20, Professor Mike Durst, and Emma Moskovitz ’18 in Durst's biomedical optics lab in McCardell Bicentennial Hall.

    Durst’s research focuses on using laser-based microscopes to image living organisms. Eventually this science can lead to new medical imaging technology that will allow us to look deep within the body without making an incision. It’s a tantalizing prospect, and students are seizing the opportunity to learn research methods in a field that could dramatically improve health care in the future.

    “I feel like I’m adding to something that’s bigger than me,” said Anthony Turcios ’20 of his work in Durst’s Biomedical Optics Lab. “Eventually, this will affect someone else’s life. It’s amazing to reflect on that and think, ‘Wow! I was a part of that process.’ I can say I contributed something.”

    For physics major and computer science minor Emma Moskovitz ’18 “it’s the first time I’ve felt like my physics was being used to solve real problems at their full complexity and not simplified versions of problems. I feel like what I’m learning is cutting edge.”

    Moskovitz’s senior project continues work she began last summer as a research assistant in Durst’s lab.

    Optics, the study of light, is one of the oldest branches of physics inquiry.

    “What’s fun about optics is that it’s not a black box; it’s more like an Erector Set for adults,” said Durst. “It’s really hands on. Basically, you can build any kind of apparatus you want because in optics there’s only three kinds of things that you ever need: a mirror, a lens, and a diffraction grating or prism.

    “And if you put those lenses and mirrors in the right orientation on the table you can publish a paper or get a Nobel Prize. . . . I’m interested in using our physics knowledge to make better microscopes.”

    Current whole-body medical imaging technologies—X-rays, ultrasound, MRIs, PET scans—have limitations, be it cost, tissue damage, or risks of radiation exposure. And none provide sufficient resolution to see cells.

    Take the example of cancer. A mammogram can spot tumorous growth, but to diagnose cancer requires a biopsy. Cells must be removed, put on a slide and examined under a microscope at sufficient magnification to prescribe treatment.

    Emma Moskovitz ’18 adjusts a laser-scanning microscope with motorized simple stage objective lens.

      Some diseases—especially those involving the brain, like Alzheimer’s or chronic traumatic encephalopathy—can only be truly diagnosed post-mortem. It’s simply too dangerous to cut into the brain to sample tissue.

      To do “optical biopsy” you need to be able to see through tissue one depth at a time, Durst explained. Whereas conventional microscopy gets that one depth by putting a thin slice of biopsied tissue on a slide, Durst uses a laser-based microscope to do “optical sectioning.” The laser illuminates one depth at a time and then the images taken at various depths are reassembled into a three-dimensional image. It’s like looking inside a loaf of bread by pulling out one slice at a time and then putting the whole thing back together, said Durst.

      The physics powering this capability involves the laser’s ability to excite two-photon absorption. In roughly oversimplified terms, we see what we see when photons—packets of light-energy—reflect off objects and are absorbed by our eyes one photon at a time. Despite the countless photons arriving from the sun all the time, for example, it’s exceedingly rare for two photons to arrive at the same spot and be absorbed simultaneously. Using a pulsed laser as a light source, scientists can create this rare phenomenon at a targeted depth.

      If you focus your laser at the right place at the right time, it will excite fluorescence only from the microscopic bit of cell you want—at the precise spot where the two photons are absorbed.

      In the lab, Durst and his students work on imaging nerve cells inside fruit flies and roundworms in conjunction with faculty members Amanda Crocker (neuroscience) and Glen Ernstrom (biology and neuroscience). They also spend long hours improving their approach to two-photon microscopy using nothing fancier than lens paper stained with fluorescent highlighter.

      “I’m interested in using physics to go faster, go deeper, and have better resolution,” said Durst.

      The Biomedical Optics Lab focuses on those goals, with a priority placed on student learning. For Durst, this commitment goes back to his own experience as an undergraduate.

      “I had a professor approach me and invite me to work in his lab. . . . And that summer research opportunity gave me some ownership. I felt like the physics department was my home. I felt like I belonged there. It made me just love all things physics.

      “And because a professor reached out to me and it made such a difference for me, I make sure to do that here for our students.”

      Together Durst and his students built the lab’s custom two-photon laser-scanning microscope from scratch. It dominates the room, perched on a one-ton optics table.

      “Everything on that table,” said Durst, “was first put there by a student as part of their project.”

      Durst carefully tailors summer lab assignments to student interest and assigns each lab assistant his or her own area of responsibility. He places a high priority on communication skills. Students present weekly lab progress reports and outline next steps for the coming week.

      “The way that Professor Durst structured our summer lab work was really great,” said Moskovitz, who was recently hired by the healthcare software giant Epic Systems. “Anthony and I had different projects that were on the same table. So they were similar enough that we could talk to each other about it. And if we ran into problems, we could bounce ideas off each other. It really made you take ownership for what you were doing.”

      In addition to the weekly lab reports, Moskovitz and Turcios both presented at the College’s summer symposium and at the Optical Society of America conference in Washington, D.C.

      A paper coauthored by Durst, Moskovitz, Turcios and 2017 physics graduate Colin Laurence is currently under peer review.

      Moskovitz noted that support and independence have both bolstered her research success.

      “Professor Durst has found the way to balance perfectly being involved and giving me guidance but also letting me figure it out for myself and struggle a bit, which is such an important part of the senior project experience.”

      Both Moskovitz and Turcios reflected on how being assigned and entrusted with their independent part of an ongoing research project instilled a new level of self-confidence.

      “I know he’s relying on me,” said Turcios. “The fact that he’s willing to trust me to work in his lab and produce results—that’s huge. I’ve never done this sort of thing before, and he was willing to say, ‘Hey, I think you have the potential to do this for me.’ When you realize that somebody’s put their trust in you, you definitely start to trust yourself and think ‘Hey, if he believes in me, I can do it too.’”

      By Gaen Murphree; Photos by Todd Balfour

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