From West Africa to the West Coast, Ottman Tertuliano's (MS '15, PhD '19) journey in materials science has brought him to the intersection of nanoscience, biomechanics, and biology. Now the AMA Assistant Professor of Mechanical Engineering and Applied Mechanics at Penn University, Tertuliano's research group explores how mechanics can combine with biology, leading to enhanced outcomes for musculoskeletal diseases and tissue engineering.
ENGenuity spoke with Tertuliano to learn about his research inspirations, his involvement with Black Scientists and Engineers at Caltech (BSEC), and how Caltech shaped his outlook on science.
ENGenuity: How would you describe what you're doing now and your professional contributions?
Ottman Tertuliano: I'm running my own research group focused on how we can rebuild tissues using mechanics. There's this idea of mechanobiology, where cells respond to mechanical stimuli in addition to biological cues, and this guides what the cells do, how they differentiate, proliferate, change their shape, etc. The non-cellular part of tissues, the extracellular matrix, is also interesting. Like collagen is mineralized in bone, these tissues respond and reconfigure to mechanical stimuli at timescales that are faster than cells can respond. We are trying to understand how that happens and how we can use mechanical loading to get cells and structures around them like collagen to adapt faster induce tissue regrowth. The long-term vision is to use 3D printing to create mechanically responsive structures around cells to get someone's limb to regrow. It's 3D printing on the body.
We're approaching that long-term vision by asking fundamental questions. The first part is understanding tissue deformation and fracture, and we do that at the nano and micro scales. We look at human bones and we fracture them and use different imaging modalities to observe how cracks propagate and arrest. Once we understand where cracks like to propagate, we can start to reinforce those aspects of the bone structure to get cracks to slow down or stop.
Another aspect is 3D printing. We're building nanostructure scaffolds—environments—for cells to interact with. This allows us to interrogate cell mechanical responses on the single-cell level. We can put a cell in an encasing and load it at different frequencies, loads, and stresses and observe how it responds to these loads. Then we can start to map out what a cell wants to do based on what we're applying to it. The simple idea we're trying to understand fundamentally is the notion that weightlifting helps strengthen your bones. Why and to what extent is that the case? What are the loads you would need to strengthen, and then beyond strengthening, enforce regeneration? When is it too much?
The last part involves metal 3D printing, which fits together with the idea of tissue regrowth. We're thinking about how to 3D print metals that are meant to interface better with the body. For example, hip and knee replacements are statistically the most successful orthopaedic surgeries, but they still lead to several problems after 5 to 10 years. This is because we typically use titanium to make those implants. Now, we're thinking about what we can do if we start to play around with materials that can be tuned to degrade in your body so that it enforces tissue regeneration and cell attachment. Basically, how do we use the mechanics and materials to guide the biology?
ENGenuity: What inspired you to get into science and then what led you to pursue materials science?
Tertuliano: When we first moved to the U.S. around 2001—we moved from Benin—I didn't speak any English. I was in ESL courses, and the courses that I did well in were primarily the math and science courses. Gabon, Benin, and Congo were ahead of what was being taught here in terms of math in elementary school, so that's where I felt comfortable. Otherwise, I felt like an outsider in the non-math and science courses. I didn't grow up with Legos or anything like that for inspiration.
At Columbia [as an undergraduate], I worked for a Black professor named Elon Terrell, who was also a phenomenal mentor. At the time, he was doing things for me that I didn't understand would help me so far down the line until I started applying for grad school and fellowships. All these things that we know look great on applications, I was already doing because he was structuring me to do them. He was also working on graphene, and there was another colleague of his, James Hone, who was working on graphene as well. I remember a quote from James in which he was describing the strength of graphene. He said something like, "graphene's strength is like if you had a single film of saran wrap, took a sharpened pencil, and you put an elephant on that pencil; that's what it would take to break it." That image made me curious and has stuck with me for over a decade. If this was how materials behave at the nanoscale, then I wanted to get into this field. I consulted with one of my mentors, Jeff Kysar, at Columbia, and at the top of his list and my list was Julia Greer [Ruben F. and Donna Mettler Professor of Materials Science, Mechanics and Medical Engineering; Fletcher Jones Foundation Director of the Kavli Nanoscience Institute].
ENGenuity: Is there a particular class or professor at Caltech that made the biggest impact on you?
Tertuliano: Other than Julia, Katherine Faber [Simon Ramo Professor of Materials Science], and I never even formally took a class with her. I was done with classes, but she came to Caltech and taught fracture mechanics. I sat in on her class, which was small, so it enabled her to deviate from the classic lecture style format and allowed for a lot of open discussion. She had a unique and practical approach to the subject matter. Also, with a lot of the papers we were discussing, she knew those people personally and could ask our questions to the authors directly. Beyond that, she was very kind with her time. She was one of the first faculty at Caltech that I wasn't working with that I would go and have meetings with. Bill Johnson [Ruben F. and Donna Mettler Professor of Engineering and Applied Science, Emeritus] also had an interesting and unique effect on me. Bill is a wonderful character and I'm very glad to have met him.
ENGenuity: How has your Caltech education influenced you?
Tertuliano: Applied Physics and Materials Science (APhMS) was oriented toward fundamentals, and being in APhMS was the first time when I knew I couldn't coast. I had to really have in-depth knowledge of the subject matter, and that starts to shape how you think about everything else. Once you start to have an appreciation for that, you take that with you and you apply it to other things, not just your work but your personal life, your interests, and hobbies. It forces you to want to build depth in everything that you do. I find that my friends and my colleagues who were also at Caltech have the same point of view where everything is focused on understanding things at the fundamental scale and building from the bottom up. You build a strong cohort going through Caltech grad school together.
ENGenuity: What advice would you give to current Caltech students?
Tertuliano: Try to have fun. Find your people and don't go through it alone. One of my colleagues at Caltech was Alessandro Maggi [Alessandro was previously featured in ENGenuity], and it would have been very different to have gone through grad school without him. We shared a similar work ethic and a similar social life, and it made the struggles easier and the fun parts more fun. Find your cohort, find your friends, and push through what is undoubtedly a very difficult but formative environment.
ENGenuity: Is there a project that you're most proud of in your career, either at Caltech or outside of Caltech?
Tertuliano: When I was at Caltech, maybe in my third or fourth year, I started getting a bit more active with Black Scientists and Engineers at Caltech (BSEC). There were four of us who were active at the time. We were pushing to do more outreach in the Pasadena area. We started developing "STEMonstrations" that were meant to be modular and engaging for high school students, and it was a lot fun. I had done things like that before, but in this instance, it was with three other detail-oriented people who I could relate to. We were trying to build BSEC in such a way that it would last beyond us. We were going for longevity and modularity and a good outreach program. I still do outreach now, I did it when I went to Stanford, and I still do it at Penn. I'm proud of that because it's lasting.
ENGenuity: What excites you outside of your work?
Tertuliano: Something I am excited about right now is runner, Deo Kato, who is based in London but was born in Uganda. He is running from Cape Town, South Africa to London. He's done things like this before, and he does it to raise awareness for social and racial injustices. Even if you take that aside, this guy is about to run across over fourteen countries and 9,000 miles. It's exciting to follow because that means he's going to have to find support from an absurdly diverse set of people. From Cape Town to London is a difficult territory. He's going to need a lot of endurance and determination to get through this, and the fact that people are going to be willing to help him get through this is also fascinating. It's exciting and motivating. I'm not doing anything near that, but I see someone pushing past a difficult struggle, and we all fight our own little struggles. It's motivation for me and helps me motivate my students as well.
ENGenuity: What is your favorite destination?
Tertuliano: In the past five years, the best trip I've done was when I went back to Benin. I was in Benin and saw family that I hadn't seen in over a decade. We did a trip from Cotonou in Benin to Accra in Ghana. It's an interesting way to travel in West Africa. You get in these seven-seater vans, but in Benin, they turn into twelve-seater vans and more. West Africa is also unstructured in terms of country boundaries. But if you can be relaxed, I think it can be one of the best trips that you can take. And the food is amazing. Drop me into 40-50% of the countries in West Africa and I'd be a happy person. I have not been to Senegal, that's where I'd like to go next because the food is amazing.
ENGenuity: What gives you the most satisfaction in your work?
Tertuliano: I love doing experiments. It's harder to do now because I have more responsibilities, but I do spend time working hands on with my new students. Seeing a difficult experiment work and get results is a feeling that can't be taken away. Also, seeing the transformation of my graduate students, especially first-year graduate students, has been rewarding, and I suspect that I'm growing through the process as well.
ENGenuity: What keeps you up at night?
In terms of work, deadlines. On a personal level, I have a younger brother who has been struggling in this job market and I think about him a lot. But he's a good kid and I think he'll push through.
ENGenuity: What gets you up in the morning?
Running. I try to be up by 5 to run every day. The nice thing about that is it makes sleeping easier.