Students build single molecule FRET microscope for world-class biological imaging lab

John Cully and James BaxterMost science student projects use existing techniques and equipment to try to answer a scientific question. But for their final year project, two University of Sheffield chemical physics students decided to apply their specialist knowledge to a practical challenge: can a pair of undergraduates build a research-grade microscope that scientists can use in ground-breaking biological and medical research?

Undergraduate masters students John Cully and James Baxter worked with supervisor Dr Tim Craggs in the Department of Chemistry to build a single molecule FRET microscope. They took a DIY approach, spending a relatively modest £40,000 to build a piece of kit that would normally cost £400,000 to buy.

Single molecule FRET microscopes are used to study the structure of molecules by pointing powerful lasers at biological samples. The light emitted makes it possible to measure the distances between different components of a molecule, working at the scale of a nanometre, or one millionth of a millimetre.

Mapping the shapes and sizes of molecules in this much detail tells scientists how they function. The ability to observe the tiny differences in individual DNA molecules means researchers can better understand illnesses that have their roots in damaged DNA, such as cancer. It allows them to shed more light on the DNA repair process and, potentially, identify new drugs to treat disease.

To build the microscope, John used visual programming software LabVIEW to control the components that make it possible to study tiny biological samples. James then 3D printed numerous parts, using computer-aided design software to work out how to arrange the lasers, lenses and fibre optics in the most efficient way.

James said: "To me one of the most rewarding aspects of the project was the freedom Dr Craggs gave us to develop and build the microscope in a creative way. He was very supportive in our ideas and put a large amount of trust building a research-grade instrument. One of the most exciting moments was the first time we saw single molecule fluorescence."

The microscope was built with simplicity in mind: researchers interested in biological problems can use it with little training, and the lasers have been shielded in such a way that it can be used in normal lighting conditions, and is no more dangerous than a CD player.

"John and James' microscope is now an integral part of my lab's work," Dr Craggs said. "Since it was built, it's been used to study the conformations of both DNA and proteins involved in DNA repair, and proteins involved in neuronal transport."

It's also been used in a major international study which was published in Nature Methods and focussed on finding new ways to measure molecules that could lead to new targeted drugs.

smFRET microscope

Only a handful of labs in the UK have the tools to study molecules in this much detail. But because parts for the students' microscope were either 3D printed, machined by the chemistry workshop or easily bought online from optics specialist Thorlabs, the team plans to produce an open source assembly kit, so that researchers can build their own single molecule FRET microscope.

James and John both did our MPhys Chemical Physics degree and are now working on their PhDs at Imperial College London and the University of Oxford. Their microscope is being put to use in the University of Sheffield’s Biophysical Imaging Centre (BICEN). This state-of-the-art laboratory, based in the Department of Physics and Astronomy, houses several high performance atomic force microscopes, and is used by researchers to develop new super-resolution optical microscopy instruments.

BICEN was created as part of the Imagine: Imaging Life project, which brings together Sheffield physicists, biologists and chemists to develop new technologies and techniques for studying the building blocks of life in unprecedented detail.

Imagine researchers build microscopes that can generate high-resolution images of cells' inner workings, create chemical compounds that make that make the individual components of a cell visible, and use these insights to help solve major biological and medical challenges.

Learn more:

Imagine: Imaging Life

Academic staff:

Dr Timothy D. Craggs

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The process of life