Biomaterials engineer Molly Stevens creates materials for tissue regeneration and ultrasensitive diagnostics

Molly Stevens has long been driven by the hope that her research will change people’s lives. Toward the end of her PhD work in single-molecule biophysics, she heard a talk by Massachusetts Institute of Technology biomedical engineer Robert Langer on how the lives of young people with organ failure might be saved by future developments in regenerative medicine. That inspired Stevens to take the skills she had developed studying fundamental molecular mechanisms into a more applied direction.

At Imperial College London, her large, interdisciplinary research group has been working on such bioengineering challenges for the past 15 years. As director of the Smart Materials Hub of the UK Regenerative Medicine Platform, a cross-university initiative, she is keen on integrating commercial, manufacturing, and regulatory expertise so that advances in materials technology actually reach patients.

In addition to developing biomaterials, Stevens’s group develops low-cost diagnostics for use in resource-limited countries. Rachel Brazil talked to Stevens about her approach to designing biomaterials and what drives her work. This interview was edited for length and clarity.

What is unique about your approach to designing biomaterials?

I’m coming at it from being interested in surfaces and how these can be decorated and manipulated, which is probably different from how a lot of other biomedical engineers would think about solving problems. We are interested in translation to the clinic, but looking into fundamental mechanisms also enables you to really think about how you’re going to design materials to interact with biology. I’ve always been interested in zooming in and understanding what happens at the interface between a material and biomolecules or cells.

Rather than just thinking about matching the bulk properties of a tissue, we are also thinking about the ways that you can structure those materials so that they interact with particular proteins or receptors on an individual cell. Our research brings in all sorts of chemistry but also nanostructuring of materials and new ways of thinking about processing materials. It needs an interdisciplinary approach, and I am so inspired by my wonderful team.

What’s an example of how you’re designing materials to better interact with cells?

We’ve done a lot of work on structuring of materials to make what we call nanoneedles (ACS Nano 2015, DOI: 10.1021/acsnano.5b01490). They’re really interesting because a cell can attach onto them. It’s like the cell is sitting on a bed of nails, and the membrane gets stimulated in a different way than how it would on a flat surface. We’ve found that it changes the way that the cell senses its mechanical environment. The cell membrane retains its integrity, but it becomes a bit more permeable, so you can start to deliver things across that membrane differently and also measure biochemical processes in the cell. So structuring on the micro- or nanoscale level results in a direct difference in how the cell perceives a material, and it can have really important medical applications, too.

How are you using materials for tissue repair?

I’ve had an interest in bone for a long time, and that has included really thinking about understanding the structure of bone. In my lab, we’ve used things like Raman spectroscopy to understand how, for example, embryonic stem cells mineralize (Nat. Mater. 2009, DOI: 10.1038/nmat2505). Those are fundamental studies that have gone on for a long time. We’ve also used electron microscopy to really zoom in and look at the nanoscale structure of bone (Science 2018, DOI: 10.1126/science.aao2189).

We’re considering combining 3D structuring of materials with interesting chemical signals that you could give to the cells at the surface of the material to try and promote mineralization. Then, how do we combine that with a slightly different material so that we can have a tissue adjacent to it that is nonmineralized—for example, at a bone-cartilage interface?

It’s a very intricate thing; the transition in the body from cartilage to bone happens in a way that’s mechanically very stable. So if you try and engineer that, but the whole thing isn’t well integrated, then it’s not going to be a successful repair. Getting a tissue that really spans across those two different materials is something that hasn’t yet successfully been re-created artificially. We also have made exciting advances in the cardiac field and in developing biomaterials for delivery of therapeutics.

What is your approach to diagnostics?

I’m very driven by making sure that the things we develop can have an impact on global health and are not so expensive that they can only benefit the developed world. A lot of the work we’ve been doing in diagnostics has been around discovering how we can get fantastic performance out of materials that could be accessible to everyone.

Some of the very exciting things we’ve done have been around particles that can provide an activity—a little bit like how artificial enzymes function—in a way that’s more stable than a normal artificial enzyme would be. So you can think about using these particles within situations where you might have extreme temperatures. We’re using these to develop a lot of different types of biosensing tests, but they’re more sensitive than traditional ones would be and can be read by a mobile phone (Nature 2019, DOI: 10.1038/s41586-019-0956-2). For HIV, we showed that we could get very, very sensitive detection with this sort of approach (ACS Nano 2017, DOI: 10.1021/acsnano.7b06229). We are also looking at this type of test for COVID-19 and for a number of cancer applications, and we’re working with industrial partners, as well as with collaborators in Africa, to take those forward.

We are excited to be working closely with the Bill and Melinda Gates Foundation to make sure that we can develop innovations that will be useful to people in the developing world. I want to make sure that the work we do impacts populations that really need those interventions in a cost-effective and scalable way.

Rachel Brazil is a freelance writer based in London. A version of this story first appeared in ACS Central Science: cenm.ag/stevens.