This week I spoke with George Lewis, a final year PhD student in the electron microscopy group, who gave me a round-up of his experience as a NanoDTC student and his work throughout his PhD, from 3D imaging, simulations as well as life after the NanoDTC. Hello George!
Thanks for speaking with me today! To introduce yourself, could you tell me a bit about you and your background?
No problem! I’m originally from Coventry, but I did my undergrad in Durham, which is in the north of England, just below Newcastle. Throughout my undergraduate degree, I studied Chemistry and Physics, so already the typical NanoDTC mix! I remember I was initially torn between studying English or Science, but I eventually chose Science because I was only interested in certain parts of English, and I thought I could study that on my own. Whereas with science, I thought it would be probably a lot harder to teach myself. Afterall, you don't have a lab at home!
Definitely not! What types of projects did you do throughout your undergraduate degree?
My course was a four-year masters course, and I my master's project was about soft matter. I was also very lucky because I got lots of chances to go and work throughout the summer in different labs and companies. I also worked at the EPSRC for a year, the funding body for the NanoDTC. I thought it was a bit weird at first, helping the people working there give out grants, to CDTs like the NanoDTC, and then joining the NanoDTC itself! But I think that gave me an insight on where the money for research comes from and what is available beyond just undergraduate degree.
That’s really interesting George, and must have given you an interesting perspective on the NanoDTC. How did you find the first year of the NanoDTC, the MRes year? Did you come to the NanoDTC knowing what you wanted to focus on?
Yeah, I was kind of set on doing my PhD on energy materials. I did three internships during my degree which were all vaguely energy related either on batteries or materials for energy application. That was what I thought I wanted to do when I arrived here. But my first mini research project with Emilie Ringe’s research group was on iron oxide nanoparticles and imaging them using electron microscopy, which essentially turned into my PhD. I thought that project was really fun! Emilie had six huge datasets and I had two months to figure out what to do with them and what was going on!
That sounds like a lot of work! But what is Electron Microscopy?
Electron microscopy is essentially a way of seeing really small things! I think most people probably recognize the word microscope. Usually with a microscope, we concentrate light on an object to look at it. With an electron microscope, it's the same idea. But instead of using light, we use electrons. The reason we use electrons is because they're actually smaller than light. If you try to use light to look at something like an atom, you can't do it using light because light itself is bigger than the atom. But electrons are actually smaller than light an allow us to get around this problem! Here at Cambridge, we can measure down to about a tenth of an Angstrom.
Ah, that makes sense! And how do you use electron microscopy in your PhD?
Yes, my PhD focused on 3D imaging, which is also called tomography. In particular, I take images of magnetic materials. At such small scales, the exact shape of the object really makes a big difference as to how it behaves, because we're at this level where nothing quite behaves how you think it should! Especially when you're talking about something like magnetism, there's lots of effects that you can only really explain by understanding the shape of the object really well. And that's what tomography allows you to study.
Taking a 3D image seems quite complicated. How do you take a 3D image using an electron microscope?
The idea is you can tilt the sample around and take a picture of it at lots of different angles. It’s a bit like an X-ray, because with an electron microscope we measure the electrons that go through the material, and you can see the density of the object as the electrons go through. If you rotated your sample around and kept on taking more images, you'd eventually be able to build up an entire 3D picture of the object. And that's exactly what we do with the electrons.
What makes the magnetic materials interesting?
One of the cool things about working in the electron microscopy group, is that I get to look at all sorts of different samples! The first sample I looked at throughout my PhD were iron oxide nanoparticles I was talking about. Iron and oxygen is basically rust, but at the nanoscale, it has very different properties as to what you would normally think rust to be. The particular particles I was looking at were donut shaped and the reason these particular particles are interesting is because they have the potential to be used as an anti-cancer therapy.
Oh wow! There's big applications for this then.
Yeah. The general idea is that you can use these magnetic nanoparticles to heat up and destroy tumours. It's called hyperthermia. Tumours are generally more sensitive to heat than the rest of the body is. So if you can heat them up even a few degrees, there's a good chance you can kill the tissue. But currently the only way you can do that is to heat up the entire part of your body, which can be very bad for you! This technique of heating up the body part is usually a last resort. But if there's any way to localize that, heating, it can be much more effective.
Nanoparticles in general are a very good way of targeting specific areas in the body. If the nanoparticles are magnetic, you can apply a really strong magnetic field outside of the person, similar to a CAT scan. They apply strong magnetic fields that don’t affect you but move the magnetic materials towards the tumour, targeting it and heating it up.
That’s amazing! So, it’s their shape that gives them this property?
Exactly. The reason we are interested in these ring shapes is because the ring gives them special magnetic properties. In particular, the ring means that they can act as though the external magnetic field is switched off when they're traveling to a tumour. This is really important because if they were permanently magnetic, they would just stick to each other. Your body would then notice this large formation of nanoparticles and try to get rid of it! So, if all the particles stuck together, they would never make it to the tumour. But because these particular particles have this ring shape, we can trap the magnetic field inside the ring so none of that field escapes, and that's what makes them act as if they're not magnetic. They can then travel to the tumour without your body attacking them!
Magnetization patterns in an iron oxide nanoring, with the shape experimentally determined by electron tomography.
So, was your project a lot of experimental work?
The whole idea of my PhD was to work towards an image of the magnetic fields themselves, and to do this I needed to simulate the magnetic fields that you would get from a particle of that shape. A lot of my PhD has been coming up with an algorithm and building a reconstruction of the field from the 3D image taken with the electron microscope, which turns out to be quite difficult. My PhD initially started out more experimental and turned into more of a coding and simulation project as time went on. I’ve been focusing on how can we get more out of the data we collect by applying certain assumptions, while still having an accurate simulation of the magnetic field.
One example of an assumption we make is that a magnetic field behaves smoothly. This means you can't have a situation where there's a magnetic field traveling, and then it just suddenly stops. I’ve focused on naturally incorporating such assumptions into a reconstruction algorithm using the 3D imaging data we’ve collected. It’s been a fun challenge, and I’ve really enjoyed tackling it!
And now that your nearly finished your PhD, where do you see yourself next?
I've been working for a company part time for the last year of my PhD. It's called WaterScope, which is a start-up in Cambridge that makes microscopes for testing the water quality in developing countries.
It's a small company, only a few of us with each of us having different backgrounds and expertise. One person in the company focuses on building the kit itself and does all the prototyping with 3D printed parts. Another person focuses on the biochemistry aspect and figures out the method of treating and analysing the water. This involves filtering a sample of water through a membrane and any E. Coli or other bacteria in the sample will get caught.
This person essentially figures out what nutrients you have to add to the trapped bacteria, how long and what temperature the kit should be at to get colonies of E. Coli developing and keep them growing. We want these kits to be transportable, but bacteria are so small that you can't see them unless you have quite a high-power microscope. But if you leave them and give them enough nutrients to let them grow for about 20 hours, you can see them by eye. And I'm working on the last aspect of the system and I’m currently trying to make an algorithm that will just look at the image of bacteria and will automatically tell you all the necessary information.
Wow George, that sounds like an amazing job! Thank you so much for speaking with me today and telling me about your work and your life in Cambridge!
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