Updated: Oct 10, 2020
Did you know some of the smallest molecules to ever exist are, theoretically, also some of our strongest? That is what it means to be a nanoscale particle. Nanoscale particles go by many names and acronyms that can get quite confusing, but you are already familiar with one tiny particle that has a great impact on our daily lives. Titanium dioxide (TiO2) nanoparticles are routinely used in makeup, creams, and sunscreens to block harmful UV rays without leaving a white paste on your skin! To be on the order of ‘nanoscale,’ a particle should be between 1 and 100 nanometers in at least one dimension. Due to the small scale, these particles have a very high surface area per unit volume, increased mechanical strength and a myriad of other fancy optical properties. These properties cannot be predicted by studying bulk material. Bulk refers to materials that are “macro” in size, just the bigger version. These nanomaterials share the chemical structure of their bulk counterparts. Macro particles are larger and present with well-known behaviors and properties. We can see and study the particle structure using optical microscopes.
Nanomaterials can exist in nature, or be made a variety of ways. One of the more fascinating ways is enabled by the ability to take a bottom-up approach. This is when researchers start with the tiniest atoms and molecules and allow them to organize themselves into larger shapes that behave in unique ways, making them very strong and even allowing them to fluoresce. This method of organizatizion, enabled by intermolecular forces, is called self-assembly. These tiny atoms or molecules are referred to as building blocks. These fascinating developments gave way to the evolution of a new scientific field called nanoscience.
Experimentation with nano-enabled behavior has been around for much longer than our modern society recognizes. Famously, medieval artisans experimented with nanoparticles to create colored paints for use during the renaissance era what we still revere today. These medieval scientists discovered that mixing gold or silver nanoparticles into stained glass paints gave way to vibrant red and yellow colors. These color expressions are size dependent! The size and shape of the nanoparticle determines the way the particles interact with light.
The photo here shows how the diameter of a gold nanoparticle changes the way light reacts with it, and it also changes its color.
Now, to be honest, my interest in nanoscience specifically was sparked simply because I like pretty things. I was fascinated by tiny perfectly ordered structures. I was fascinated with studying how researchers could control this behavior using a variety of techniques. These techniques can be simple or complex, depending upon the chemical structure, intermolecular forces, and nature of the tiny building blocks. Did I mention this ability to make nanostructures exists naturally? Yes, nature has developed a myriad of unique nanostructured patterns that scientists envy. Some examples include the DNA double helix, the nanostructured hydrophobic patterns on a cicada wing and nanostructured patterns that allows a gecko to have its super sticky toes.
Scanning electron microscope (SEM) image of a cicada wing. Scientists and engineers work to replicate this structure which exists naturally using self-assembly.
Xie, Guoyong & Zhang, Guoming & Lin, Feng & Zhang, Jin & Liu, Zhongfan & Mu, Shichen. (2008). The fabrication of subwavelength anti-reflective nanostructures using a bio-template. Nanotechnology. 19. 095605. 10.1088/0957-4484/19/9/095605.
Bottom up: The use of chemical or physical forces that operate on the nanoscale to assemble basic units into larger structures.
Building blocks: nanoparticles, collections of atoms, or very small molecules.
Chemical structure: The arrangement of chemical bonds between atoms in a molecule. For nanoparticles, these bonds do not change, they are just chipped down to their very smallest pieces.
Intermolecular forces: Forces helping interactions between molecules including forces of attraction and repulsion. At the nanoscale, these forces depend upon the neighboring particles which are extremely tiny atoms or ions. Scientists and engineers can study these interactions using powerful imaging techniques.
Nanoparticle: A particle that is between 1-100 nm in any one dimension.
Self-assembly: The fancy name for bottom up approaches used to produce small clusters of atoms.
Now that I have shared why nanoscience is interesting to me, let me step back a bit and be more personal.
When I started college many moons ago, I declared my major as physics. Physics is a very complex subject to understand, so for someone like me who was not known to be good in math, I faced some adversity. To start, I had never taken calculus and everyone knew I wanted to study music. However, from my perspective, physics was the basis of all things. Knowing a little about the behavior of matter, the fundamentals of mathematics, and the way molecules interact with each other was imperative for understanding the world. If I wanted to go anywhere at all and enjoy doing it, I had to start broadly and I felt like I had to start within a subject I had never been allowed to access before.
My passion for physics was rekindled as a college freshman, but I had always loved science and engineering. Let me tell you about an even younger version of me. As a young outspoken, hyperactive Black girl, I was never encouraged to study math. I will never forget my advanced 6th-grade math teacher at a predominantly white school refusing to help me. I had been placed into gifted programs in elementary school, and I was supported by my Black 5th-grade teacher. I was confident and ready when it was time for middle school. As I transitioned to middle school, my parents fought to keep me on the academically gifted track, but middle school is a different arena. Many disparities between Black and white children emerge during this time, as they did for me. I quickly fell behind in all of my advanced classes. Especially the math class. I developed severe symptoms of anxiety, and I did not “get it,” so I was told math was not for me. The class moved on to something new every day and I cried over my homework, which I never understood. My teacher stared coldly at me as I asked questions hopefully, but it was ingrained in my young 11-year-old mind that if I could not keep up, I did not belong. I learned that asking questions in class meant I would be mocked. And mocked I was throughout high school, college and even in graduate school. I was mocked by my peers, tutors, teachers, and eventually professors.
I switched schools after sixth grade, but the damage was done. I felt broken inside and I was losing my ability to speak up for myself without being mocked by teachers or getting into trouble for talking out of turn. When I was 13, I was old enough to understand what was happening around me and I realized I was facing discrimination. That also meant I was old enough to be criminalized for my actions. Being in a new school surrounded by a much more diverse peer group was healthy for me, but the microaggressions remained, most of my teachers were still white, and the cross between racism and sexism erected a barrier I fought to overcome for the duration of my educational career.
By the time I got to high school, teachers looked at my record and grades and told my parents that I would be ok with taking regular math. My parents, wanting me to have every opportunity I could imagine still inquired about how these classes would impact my future when it was time to apply for college and choose a major. My teachers, as polite as they seemed, said I would never need an advanced math class or a fancy calculator, and math beyond Algebra 2 would not benefit me for what I would want to do. (How could they know?) They implied I made these choices, but when I asked about physics in tenth grade, I was told I would have needed to be a tenth grader in pre-calculus to enroll in the physics class in the coming year (eleventh grade). I was taking geometry in tenth grade, so I never had the chance. By then it was “too late” for me. I was too afraid of math to challenge them, I knew I wouldn't do well, so I pivoted and plunged into other subjects that were available to me. I chose subjects that did not require the math classes I wasn’t allowed to take, including english, music, and the arts.
Even though I continued to fight for myself, as we do, my light-hearted, talkative personality and outspoken attitude meant I was nobody’s favorite. Basically, nobody was willing to fight to have me in advanced math classes where I'd stand out. Until I got to college I had been in "regular" math classes. The most advanced class I took in high school was algebra 2. Let me be clear for my young Black girls: There is nothing wrong with taking regular math classes and there is nothing wrong with not understanding any subject the way it is taught, but this is especially true for math. It is an abstract subject, and American schools put Black children at a disadvantage from the very beginning. I needed to be in average classes, I needed the extra help and more. I needed tutors and I needed to count with my hands. I needed to solve equations the long way, writing out each and every step. I needed more time to solve problems, and I did not get problems right the first time… Or the second time.
The problem with the delineation between “gifted” and “average” students in grade school is that one group gains access to resources while the other group is left out. For me, it meant I was constantly told I was not good enough and would never be able to enjoy and understand math. This means we aren't even given the chance to try. Without our input as students, we have “leaked out” of the S.T.E.M. pathway completely. By the time we are applying for college, it has been decided. Due to our transcripts, we have been locked out of an entire world of opportunities in S.T.E.M. Moreover, lawmakers and academics continue to speak on our behalf, opining how "We just did not want to be scientists, mathematicians, or engineers" and accept it as the status quo.
As my ambitions broadened, I developed an immense appreciation for my younger self and her ability to not be deterred by society’s desire to label me and put me in a box. My job now is to be a nanoscientist, whatever that means, yes, but more importantly, I have a duty to remind and encourage young Black and brown children that this world doesn’t get to tell us who we are or who we should grow up to be.
Due to the special nature of nanoparticles that we discussed earlier, I work to study how we can put nanoparticles into a variety of macroscale systems so they can be stronger and lighter. I spend a lot of time in the lab at my university, the Joint School of Nanoscience and Nanoengineering (JSNN) in Greensboro, North Carolina, and before the pandemic, I spent time learning about fabricating aerogels with the experts at NASA Glenn. I also spend time volunteering and live-tweeting rocket launches with the space science community for my social media followers and my mentees. Everyone loves rocket science!
A lucky chance: I met astronaut Winston Scott at Kennedy Space Center during the commercial resupply launch at the CRS-19 NASA Social in December 2019. Representation matters!
Haley Harrison is a nanoscientist and doctoral candidate at the Joint School of Nanoscience and Nanoengineering (JSNN) in Greensboro, North Carolina. She holds a BS degree in Physics and an MS degree in Earth Science. Her research interests include boron nitride nanomaterials, aerogels, and other lightweight materials used as thermal protection in launch vehicles.