Season 6 - Episode 608
“Safety by design” is a focus of Christie Sayes’ work at the intersection of toxicology and materials science. An associate professor of environmental science at Baylor, Sayes uncovers unintended consequences of new materials to promote safer design. In this Baylor Connections, she takes listeners inside products that utilize advanced materials, talks about her research with the U.S. Air Force and unpacks the “lung-on-a-chip” she developed to simulate the lung in real operational environments.
Derek Smith:Hello and welcome to Baylor Connections, a conversation series with the people shaping our future. Each week we go in depth with Baylor leaders, professors, and more discussing important topics in higher education, research, and student life. I'm Derek Smith, and today we are talking with Dr. Christie Sayes. Dr. Sayes serves as associate professor of environmental science at Baylor. An Air Force Research fellow, her focus is at the intersection of toxicology and advanced materials, and its led her to develop among other products along on a chip, which simulates the human lung in real operational environments. Attention to the unintended consequences of new materials helps promote human health as advancements lead people to interact with a new class of products. So you can tell there's a lot of different angles to her research as she joins us on the program today. Dr. Sayes, thanks so much for joining us. It's great to have you here.
Christie Sayes:Thanks, Derek. It's great to be here.
Derek Smith:Well, it's great to visit with you and unpack what it is that you do. So let's start off, hopefully something that people can latch onto quickly. If we were to walk around the grocery store, a department store and just look at products in there, what are some that people would see that tie into what you do?
Christie Sayes:Wow, what a interesting question, Derek. I would say what type of product doesn't have any sort of advanced materials in it these days? As you mentioned before, I'm at the intersection of toxicology and material science, and within material science, that word is advanced materials. So it's often the same materials that we're used to thinking about such as textiles in our clothing at a department store. But if you think about an advanced material, what if that material could help reduce odor, for instance, in your athletic wear? So it's often those advanced kind of smart materials that you hear about that have the advanced materials like engineered nano materials or advanced smart carbon fibers. These things are in textiles. They're in food packaging, and even the cars that we drive every day.
Derek Smith:Visiting with Dr. Christie Sayes, and what are some questions that you try to answer through your work? As we know now, kind of what it is that we can see in the real world, what are some questions you're trying to ask?
Christie Sayes:Well, now I can put on my toxicology hat, right? So of course I am absolutely 100% a champion for advanced materials and other technology such as nanotechnology, picotechnology, and all the like to be successful and to improve our quality of life. After all, that is what technology is, some application to improve our quality of life. But I often think about if things maybe were unintentional or maybe things were used not by the manufacturer's intended use. So for instance, what if that food packaging was accidentally taken by a kid, like a toddler, and they started chewing on it? The intended application of that food packaging, which may include advanced materials, it wasn't meant to be eaten. It was unfortunately meant to be just thrown away in the trash and go to our landfill, which also as an environmentalist, that causes other problems too. But let's just take that example. If a child were to chew or eat on that food packaging material, there are no safety studies out there by the USDA, US Department of Agriculture or the FDA, Food and Drug Administration, that were designed to test such unintended consequences. So this is where my toxicology hat comes in, and I want to be able to understand if there are unintended consequences, if you were to swallow those advanced materials that may have leached from the food packaging, or if you were just to chew that particular material and it makes it to your stomach.
Derek Smith:And as we move forward in the program, I think we can picture that on a larger product level. We talk about what? Airplanes and servicemen and women and things of that nature.
Christie Sayes:Absolutely. The occupational workforce even, I mean, there are people out there including US consumers that are breathing in off-gassing. Or if it was a production line, often there is an aerosol that's being produced. An aerosol can be fumes or vapors that we breathe, but it also could be particulates. You might have heard particulate matter. Particulate matter is an air pollution that comes from the complete or incomplete combustion of carbon, but that aerosol doesn't have to be just carbon. It can be metals. It could be other types of materials. One common one we're looking at the lab right now was called silica, SiO2, silicon dioxide. And it's made in a variety of different processes to be able to increase its malleability or its translucence, or even if it's conductive versus insulating. And all those different processes produce different types of particulates that can easily be aerosolized. And if you're in a room where that's being aerosolized, you're breathing that in.
Derek Smith:Let's just say you're talking to a colleague from another discipline, another building on campus, and they said, "Oh, so what do you do?" How would you describe that in this short amount of time?
Christie Sayes:Man, to another faculty member or graduate student, I often say I have expertise at the intersection of chemistry and toxicology. But to a even higher level, I would say materials, material science, and something called environmental health. Environmental health is of course concerned about the health of the environment, but as humans, we're part of that environment. So it really dives deep into human health effects too.
Derek Smith:So you're in the Department of Environmental Science. Any other, are there joint appointments there with that?
Christie Sayes:Well, yes. I do interact a lot with the Department of Biology as a toxicologist. Toxicology focuses, my discipline, focus on human health, so things like anatomy and physiology and molecular mechanisms, that's all related to our great Department of biology here at Baylor. I'm also connected with the interdisciplinary faculty of material science. Now, the material science program, as we have it set up right now, is a degree granting program. You know what? Right now we're starting with a PhD or a doctorate level type of program, training program, where students take interdisciplinary sciences and sustainability and engineering, nanotechnology and some of these other types of advanced materials optics, for instance. That interdisciplinary program will eventually have undergraduate degree or a minor as well. And we will be a full faculty that are really supportive of each other in going after some of the biggest challenges that the world faces today and in the future.
Derek Smith:That's exciting. Is that an outgrowth of Illuminate as we look at that focus on material science?
Christie Sayes:Absolutely. Material science is a pillar of the Illuminate way of thinking and its strategy, and I'm very proud to be a part of it
Derek Smith:Talking with Dr. Christie Sayes. So let's talk now about that material science side even a little bit more, and the work you do, particularly with the Air Force, really a great example. So the Air Force is an important partner in your work. So first off, how did you connect with them and become an Air Force research fellow?
Christie Sayes:I was very lucky in my training personally through graduate school and into my postdoc position where I was able to interact with a lot of different subject matter experts. I got my degree, my PhD, at Rice University. And at the time, there were a couple federally funded centers of research there. And when you're at a university that has federally funded centers, they often open their doors to all kinds of stakeholders, be it the public, but also government officials including feds from agencies like the Environmental Protection Agency, or the CDC, or DOD. In my interactions through the centers at Rice and then into my postdoc as an industrial postdoc at the DuPont Company, I interacted with many people from the DOD who were thinking about advanced materials and how they might use them. So one of my mentors was my current program officer at the Air Force Research Laboratory. He's probably been as a mentor of mine for 20 years, and we love to tell our joint students that we've been connected for 20 years years. They always find that very interesting, that someone can graduate from being someone who was a mentor to actually being your close, trusted colleague and collaborator.
Derek Smith:That's great. And it's led to some pretty cool things over the years too.
Christie Sayes:Really cool things. And I've gotten to see how the Air Force strategies have changed. You would think that maybe they would stick to one thing and run with it. But no, I mean, they go lightning fast. They have different research agendas every couple of years, and they expect and demand of its partners and collaborators that if this is a two-year program, then you're going to get it done from the lab to the market in that time period.
Derek Smith:Wow. That's pretty intense, or at least it sounds like it at times.
Christie Sayes:It does. Puts a lot of stress, but the opportunities are awesome for both myself and of course, more importantly, my trainees because often they will want to go into a research position in the federal government. So far I've graduated at least two PhD students who are NRC posts, National Research Council postdocs, and both of those individuals went on to do their postdocs in the DOD, which is awesome for their career.
Derek Smith:Visiting with Dr. Christie Sayes. Well, let's talk about some of the questions that you're trying to answer, the problems you're trying to solve for them. What are some of the areas, the angles you've taken in your research with the Air Force?
Christie Sayes:Yeah, that's a really great question, and I really like that word angle, what perspective, what direction I come from. Well, I would define that as these three little words called safety by design. This is exactly the motto that we use in our laboratory and what we use at this interface of material science and environmental health. As I said previously, we are champions of advanced materials and additive manufacturing and things that are next generation that help the US economy and of course make technology work globally to make everybody's life a better place. But when you're thinking about the design of a new material and a new product and the application of that material or product, you kind of have to think about the safety of it as well. So one particular aspect that I can share with you is that we synthesize and create a lot of different engineered nanomaterials in my laboratory. We focus on colloidal based construction of these particles from a bottom-up approach, meaning we break down starting materials that are from the earth, break them down to their molecular and even elemental composition, and then start building them back up into a material that we want, being a perfect sphere that's in the nanometer size range, or if they grow into very long whiskers or rods or wires. These types of materials, what we like to do for the design aspect of this is to eliminate harsh solvents that are used to create these advanced materials. All of our synthesis for the nanomaterials that we make in the laboratory is aqueous-based, water-based. And we find this is really important for us to do because the solvents that we create, it's not a toxic solvent water. Well, I need to correct myself. Everything is toxic at a certain dose, but it's not a harsh solvent that would cause some immediate damage to an environment or to a human if they were evaporating off that solvent. We evaporate off water into water vapor, and then the collected residue is our waste. It's much less in volume and mass, and it can be degraded in an incineration type process, which we think about when we think about the product lifecycle and the product value chain of these different additive materials into products.
Derek Smith:So if you find something that is intriguing that seems to you like it's worthy of further study, what happens then? You're in the lab, you're working with this water set up, and what happens then? What's next?
Christie Sayes:So once we produce our engineered nanomaterials, we then think about what its potential application might be, and of course we think about how it could be misused. So at the very beginning, we perform some, what's called, high-throughput screening to be able to see what is an acceptable exposure limit if you were exposed to this particular advanced material through the air, through ingestion, or even dermally. The lung is the target organ for if you breathe something in. The gut is the target organ if you ingest something. And of course your skin is the target organ if you were exposed to it dermally. We have each of those organ systems built on a chip. You mentioned at the beginning of the program-
Derek Smith:Yes. This is where it ties in.
Christie Sayes:Yeah. The lung on the chip model, we use that lung on a chip model to do some high-throughput screening of the various nanomaterials. This is tens and hundreds of different materials with different surface coatings and different shapes and sizes and even colors. And we can aerosolize those materials and look at what the effects would be if you were to breathe this in but using a simulated model of the lung on the chip. The lung is a complex organ. Of course, we can't recapitulate everything going on in an intact in-vivo or whole animal, whole human lung. But we can get some specific biomarkers to be able to say if there is a potential to have dysfunction in the lung, or maybe some biochemical changes that are not really physiologically relevant.
Derek Smith:So what does this look like? You've got the lung on a chip. I'm sure all of us when we hear that, have a different picture in our head.
Derek Smith:So what does it look like and then how do you utilize that setup to determine that?
Christie Sayes:Yeah, so with any organ on a chip model, our skin model, our gut model, our lung model, and our newest development of the brain on a chip, all of these things must be submerged in serum, a simulated serum, commonly known as cell culture media. What it is a simulated serum, blood serum, that these cells are submerged when they're kept in the incubator and ready for use. And then when we use them, we take them out of the womb, I suppose. Our incubator, we call it the farm. It's where we keep them and store them when we're not using them. We take them out and it's usually a destructive process where each long on a chip or each organ on the chip, once we use it for an exposure, that is a completely destructive process because we use all of the cells and the fluids that make up that particular organ in our endpoint analysis. And it's that endpoint analysis where we look for things, biomarkers or surface tension changes, or if there were genes or proteins that were perturbed, was there a pathway that was initiated? One of our major pathways that we look for is inflammation, and inflammation sometimes can turn into irritation or sensitization. I'm starting to get into some alphabet soup here. But just as a brief thing, irritation is something that we individuals, our organs and our tissues can get over. After just one exposure, we can recover from it. Maybe we have some sort of manifestation of a skin condition or outbreak like acne, but that goes away. If it was a sensitization reaction, that's more of a chronic condition, and that's what we really are most sensitive to. We're looking at these advanced materials, whether we breathe them in, we ingest them, or they're applied to our skin dermally, looking to see if there's a sensitization reaction occurring that would then keep us allergic to that material and cause some real serious adverse outcomes if we were to continue to be exposed to them later on.
Derek Smith:What might exposure to these materials over time look like?
Christie Sayes:Absolutely. We can think of some of the war fighters and the airmen, even civilians that are part of the DOD. Whenever they work with these materials, they really put on a construction worker hat. So if just for the Air Force, if we're thinking about the airplane and other flight vehicles, they have to manipulate that particular structure for replacements or reconstruction of a particular aircraft. And as they're working and wearing and tearing that particular material, they're producing an aerosol. Without the proper PPE or personal protective equipment, they may be unintentionally exposed to some of the advanced materials, the additives that are part of those sheetings and wires and plastics and any other material that is part of the aircraft. Without the PPE, they're exposed to it. A lot of my recommendations, whenever I talk about the findings that we have in the laboratory always goes back to engineering controls or use of personal protective equipment. We remember COVID where we had to wear face masks all the time. But I have to say, I'm one of those people that firmly believe because I do the testing that face masks can really protect your lungs. It can protect and keep you from breathing in materials, particles, viruses, anything that you're thinking of that's in our air. It keeps us from breathing them in and getting to our lungs or breathing them in and going directly through the olfactory nerve to our brains. So the face mask is often used, a recommendation that we want people to use when they're working with advanced materials, especially in construction.
Derek Smith:That's great. As we visit with Dr. Christie Sayes, so they can protect themselves or you can adjust, I suppose, with that data, adjust essentially what kind of materials they want to use down the line. Is that fair to say as well?
Christie Sayes:Yeah, Derek, that's a really good way of looking at it. That's where that safety by design concept comes in. So if there were two or three or 10 different additives that we could potentially add to plastic, for instance, and we would still get that same exploited property that we want, let's just say transparency, we would test all 10 of those materials at the same time side by side and look for which one induces the least toxic effect. That would be our recommendation for moving forward for advanced manufacturing and making these materials on the bulk scale.
Derek Smith:Well, Christie, it's been pretty fascinating looking back at the work you've done, and we mentioned not just a lung on a chip, but brain on a chip-
Derek Smith:Or gut on a chip.
Christie Sayes:And skin.
Derek Smith:And skin. So a lot of exciting things ahead. With that, are there any other projects that are on the horizon for you that you're particularly excited about or that we should be watching for more information for?
Christie Sayes:Yeah, I definitely think that we should keep our ears and eyes peeled on what's going on overseas with the military and these things called burn pits that they have to use to get rid of their waste. There is no waste management type system whenever you build a camp overseas in some of these war occupied countries. So what they do is dig a big hole in the ground and put all of their waste, be it food waste or human waste or plastics, wood metals, and they throw all of this material into one bonfire. Then they destroy the material and make it less massive, less volumous by burning it with kerosenes and other ignition type fluids. And those all produce an incredible amount of toxic aerosols. I'm interested in what those potential effects are for not only our brave men and women overseas, but also for the local people in that area. If they're downwind of that material, then they're breathing it in as well. And this is a big problem. As an environmental health scientist, I'm really curious about what are the immediate and long-term damages, and then I want to help find the solutions. We still have to get rid of this massive amount of waste, but how can we do it safely for humans?
Derek Smith:Well, it's exciting to see how your research, as we talk about with the military, with the Department of Defenses and the Air Force, it ties back to us as civilians as well.
Derek Smith:That's neat to see. Well, Dr. Christie Sayes, thanks so much for joining us. Real great to have you on the program today.
Christie Sayes:Thank you, Derek. It's been great.
Derek Smith:Dr. Christie Sayes, associate Professor of Environmental Science at Baylor, our guest today on Baylor Connections. I'm Derek Smith. Reminder, you can hear this in other programs online, baylor.edu/connections, and you can subscribe on iTunes. Thanks for joining us here on Baylor Connection.