The subtle allure of materials science and engineering

You know what’s funny?

If you were to have asked me during my senior year of high school what Materials Science and Engineering (MSE) was, I wouldn’t have the slightest clue how to answer. Now, less than five years later, I’m sitting here writing this as a first-year MSE PhD student, and were I to be asked that question now, I could go on for hours about how it is one of the coolest, most interdisciplinary fields anyone could get themselves into.

MSE is often an overlooked discipline due to it not being a “major” (read: Mechanical, Chemical, Electrical) engineering discipline. What most people don’t realize, however, is that practically everything you do and take advantage of on a day-to-day basis, you have a materials engineer to thank for. That iPhone of yours you stare at for over an hour a day? It’s a materials masterpiece.

Consider how many times you’ve accidentally dropped your phone (whether it be on the ground or on your face while you’re laying in bed) without the screen cracking. You have the engineers at Corning to thank for that. Corning’s Gorilla Glass is no ordinary day-to-day window glass; it’s a special aluminosilicate glass that has undergone a process called ion exchange. Basically, what happens is you dip a sodium-containing glass into a hot bath of potassium ions, where a literal exchange happens between the sodium and the potassium atoms. Since potassium is ever so slightly larger than sodium, the glass is put under compression. If anyone wants to break this glass, they must first overcome the genius behind its reinforcement. You can read more about how gorilla glass is made [here].

gorillaglass

A sample of corning’s Gorilla Glass put under a three-point bending test.

The materials genius behind the iPhone isn’t limited to just its screen. The production of the hardware that makes your phone so fast was also a materials problem—getting those two billion transistors to fit on a chip inside your iPhone took literal decades of work.

Problems like these are what brought me to take on MSE as my undergraduate major, but the interdisciplinary nature of the field is what convinced me to stay.

My “Intro to MSE” professor (and my eventual undergraduate research advisor), Dr. Laura Fabris, would often tell us about her research. She worked on the production of gold nanoparticles (?!) that could be used for disease/biological marker detection. Her research fascinated me, and was what originally got me interested in the region where materials and biology overlap. The more that I read about what was being done, the more I longed to be a part of it. These desires have brought me to the Johns Hopkins University for my graduate studies, and ultimately the Institute for NanoBioTechnology so that I could gain further insight and training on what is being done at the forefront of my field.

goldnanorods

Transmission Electron Micrograph of Gold Nanorods in solution.

Now that I’m here at Hopkins, I’ve found myself working on the synthesis and self-assembly of polymeric nanoparticles used for biomedical applications. Did you know that most drugs on the market that are used for treatment of diseases such as cancer are hydrophobic? Now, consider the fact that your body is about 60% water… This makes delivering drugs to certain areas of your body a huge problem, and has posed a challenge for hundreds of scientists and engineers. Using the polymeric nanoparticles my lab synthesizes, we can store these drugs in a safe “vehicle” so that they may safely arrive wherever they are needed. Cool, huh?

With that, I’d like to leave you with the video from Corning that truly was the tipping point to my choosing MSE. Although it no longer lines up with the direction I’m taking myself, it shows how the future lies in the hands of engineers who believe in the power of materials, and I hope I have inspired you to consider the impact materials make in both our everyday lives and the (not-so-distant) future.

Lazaro Pacheco is a first year PhD student in the Materials Science and Engineering department at the Johns Hopkins University. He is a member of the Herrera Lab, and he is currently working on measuring the polydispersity of polymer chains that are ‘grafted from’ a central polymeric backbone.

Media inquires about INBT should be directed to Mary Spiro at mspiro@jhu.edu.

REU Profile: Microfluidics internship teaches patience, perseverance

Alex Chavez is a rising sophomore at University of Central Florida where he is studying Mechanical Engineering and Biomedical Sciences and minoring in Bio-Engineering and Mathematics. He spent the summer in the Materials Science and Engineering laboratories of Kalina Hristova and Peter C. Searson as part of the Johns Hopkins Institute for NanoBioTechnology Research Experience for Undergraduates program (INBT REU). His mentor was Alex Komin, a PhD candidate in the Searson group.

Alex wanted to write about his experience at Johns Hopkins in the INBT REU program in a blog post as follows:

This summer at the INBT REU has been a challenging and rewarding experience that has allowed me to investigate interesting topics at the interface of microfluidics, biological cells, and drug delivery. My research is focused on fabricating microfluidic devices, which allow to easily introduce the fluorescent molecules of interest to the cells and wash them out while doing live-cell fluorescence imaging.

Alex Chavez

Alex Chavez

While the main purpose of the device is to measure the rates at which fluorescent molecules can enter and exit cells, the applications of this microfluidic device may extend to the measurements of inhibition and cell viability without taking the cells out of the microscope. One of my research goals was to optimize the microfluidic device, such as the tube connection and battling with the bubbles that could ultimately stop the flow of the fluid in the microfluidic vessel. I have enjoyed learning how to fabricate microfluidic devices, work in the cleanroom, culture cells, seed cells, and to work with a confocal microscope.

This experience has given me the chance to learn from an expert in cell culture and learn more about the JHU community. Being mentored by an expert that can guide me and give me hints on what to do next, as well as to let me explore my own potential, has given me an incredible insight into the life of a graduate student. It has taught me the patience, diligence, and passion, to name a few skills, which a researcher should possess to perform their best in the laboratory. It has also showed me that sometimes experiments planned for a specific day may be delayed due to troubleshooting the device. It has also made me realize that if you keep on working and putting 100 percent of yourself, one day when you least expect it, you might be able to attain publishable results. This experience has ultimately taught me to keep on working and fighting for the love and advancement of science and drug delivery.

My experience at INBT has guided me and confirmed my thirst to pursue an advanced degree in biomedical engineering. My peers in the INBT REU program have inspired me to push myself to the limits and continue to work hard in order to know as much as them. I have visited Baltimore’s Inner Harbor and have had dinners with my peers. I’m blessed and truly privileged to have had this experience, including talking with my Puerto Rican roommate, Jean Rodriguez, about future goals and aspirations.

My mentor, Alexander Komin, has taught me invaluable skills that I will cherish and continue to further develop in the future. Thank you very much INBT for allowing me to further my research experience.

All press inquiries about this program or about INBT in general should be directed to Mary Spiro, INBT’s science writer and media relations director at mspiroATjhu.edu.

 

REU student profile: Ian Reucroft

Sitting at what looks like a pottery wheeled turned on its side, Ian Reucroft is using a method called electrospinning to create a nano-scale polymer fiber embedded with a drug that encourages nerve growth. The strand is barely visible to the eye, but the resulting fibers resemble spider web.

Ian Reucroft, a rising junior in Biomedical Engineering at Rutgers University, is working in the medical school campus laboratory of Hai-Quan Mao, professor of materials sciences and engineering at Johns Hopkins University. He is part of Johns Hopkins Institute for NanoBioTechnology’s summer REU, or research experience for undergraduates program.

Ian Reucroft in the Mao lab. Photo by Mary Spiro.

Ian Reucroft in the Mao lab. Photo by Mary Spiro.

“We are developing a material to help regrow nerves, either in central or peripheral nervous systems,” said Ian. One method of doing that he explained is to make nanofibers and incorporating a drug into those fibers, drugs that promote neuronic growth or cell survival or various other beneficial qualities. The Mao lab is looking into a relatively new and not well-studied drug called Sunitinib that promotes neuronal survival.

“We make a solution of the component to make the fiber, which is this case is polylactic acid (PLA), and the drug, which I have to dissolve into the solution,” Ian said. Although the drug seems to remain stable in solution, one of the challenges Ian has faced has been improving the distribution of the drug along the fiber.

This is Ian’s first experience with electrospinning but not his first time conducting research. He plans to pursue a PhD in biomedical engineering and remain in academia.

For all press inquiries regarding INBT, its faculty and programs, contact Mary Spiro, mspiro@jhu.edu or 410-516-4802.

Hopkins’ Herrera-Alonso earns NSF CAREER award

Margarita Herrera-Alonso

Margarita Herrera-Alonso, assistant professor in the Department of Materials Science and Engineering, has received the National Science Foundation CAREER Award. Herrera’s CAREER funding will support her goal of better understanding the structure and property relationships of new polymers inspired by nature.

Her research will enable these building blocks to be used in the context of other bio-inspired materials applications, such as drug carrier design. The CAREER Award recognizes the highest levels of excellence and promise in early-career scholars and teachers.

Herrera joined the Johns Hopkins University faculty in early 2010. She is an affiliated faculty member of Johns Hopkins Institute for NanoBioTechnology. She earned her PhD in polymer science and engineering from the University of Massachusetts at Amherst. Find out more about the projects the Herrera Group is working on at this website.

 

Nanowires Deliver Biochemical Payloads to One Cell Among Many

Imagine being able to drop a toothpick on the head of one particular person standing among 100,000 people in a sports stadium. It sounds impossible, yet this degree of precision at the cellular level has been demonstrated by researchers affiliated with The Johns Hopkins University Institute for NanoBioTechnology. Their study was published online in June in Nature Nanotechnology.

Arrow points to nanowire placed on cell surface. (Image: Levchenko/Chien labs)

The team used precise electrical fields as “tweezers” to guide and place gold nanowires, each about one-two hundredth the size of a cell, on predetermined spots, each on a single cell. Molecules coating the surfaces of the nanowires then triggered a biochemical cascade of actions only in the cell where the wire touched, without affecting other cells nearby. The researchers say this technique could lead to better ways of studying individual cells or even cell parts, and eventually could produce novel methods of delivering medication.

Indeed, the techniques not relying on this new nanowire-based technology either are not very precise, leading to stimulation of multiple cells, or require complex biochemical alterations of the cells. With the new technique the researchers can, for instance, target cells that have cancer properties (higher cell division rate or abnormal morphology), while sparing their healthy neighbors.

“One of the biggest challenges in cell biology is the ability to manipulate the cell environment in as precise a way as possible,” said principal investigator Andre Levchenko, an associate professor of biomedical engineering in Johns Hopkins’ Whiting School of Engineering. In previous studies, Levchenko has used lab-on-a-chip or microfluidic devices to manipulate cell behavior. But, he said, lab-on-a-chip methods are not as precise as researchers would like them to be. “In microfluidic chips, if you alter the cell environment, it affects all the cells at the same time,” he said.

Such is not the case with the gold nanowires, which are metallic cylinders a few hundred nanometers or smaller in diameter. Just as the unsuspecting sports spectator would feel only a light touch from a toothpick being dropped on the head, the cell reacts only to the molecules released from the nanowire in one very precise place where the wire touches the cell’s surface.

With contributions from Chia-Ling Chien, a professor of physics and astronomy in the Krieger School of Arts and Sciences, and Robert Cammarata, a professor of materials science and engineering in the Whiting School, the team developed nanowires coated with a molecule called tumor necrosis factor-alpha (TNF?), a substance released by pathogen-gobbling macrophages, commonly called white blood cells. Under certain cellular conditions, the presence of TNF? triggers cells to switch on genes that help fight infection, but TNF? also is capable of blocking tumor growth and halting viral replication.

Exposure to too much TNF?, however, causes an organism to go into a potentially lethal state called septic shock, Levchenko said. Fortunately, TNF? stays put once it is released from the wire to the cell surface, and because the effect of TNF? is localized, the tiny bit delivered by the wire is enough to trigger the desired cellular response. Much the same thing happens when TNF? is excreted by a white blood cell.

Additionally, the coating of TNF? gives the nanowire a negative charge, making the wire easier to maneuver via the two perpendicular electrical fields of the “tweezer” device, a technique developed by Donglei Fan as part of her Johns Hopkins doctoral research in materials science and engineering. “The electric tweezers were initially developed to assemble, transport and rotate nanowires in solution,” Cammarata said. “Donglei then showed how to use the tweezers to produce patterned nanowire arrays as well as construct nanomotors and nano-oscillators. This new work with Dr. Levchenko’s group demonstrates just how extremely versatile a technique it is.”

To test the system, the team cultured cervical cancer cells in a dish. Then, using electrical fields perpendicular to one another, they were able to zap the nanowires into a pre-set spot and plop them down in a precise location. “In this way, we can predetermine the path that the wires will travel and deliver a molecular payload to a single cell among many, and even to a specific part of the cell,” Levchenko said.

During the course of this study, the team also established that the desired effect generated by the nanowire-delivered TNF? was similar to that experienced by a cell in a living organism.

The team members envision many possibilities for this method of subcellular molecule delivery. “For example, there are many other ways to trigger the release of the molecule from the wires: photo release, chemical release, temperature release. Furthermore, one could attach many molecules to the nanowires at the same time,” Levchenko said. He added that the nanowires can be made much smaller, but said that for this study the wires were made large enough to see with optical microscopy.

Ultimately, Levchenko sees the nanowires becoming a useful tool for basic research. “With these wires, we are trying to mimic the way that cells talk to each other,” he said. “They could be a wonderful tool that could be used in fundamental or applied research.” Drug delivery applications could be much further off. However, Levchenko said, “If the wires retain their negative charge, electrical fields could be used to manipulate and maneuver their position in the living tissue.”

The lead authors for this Nature Nanotechnology article were Fan, a former postdoctoral fellow in the departments of materials science and engineering and in physics and astronomy; and Zhizhong Yin, a former postdoctoral fellow in the Department of Biomedical Engineering. The co-authors included Raymond Cheong, a doctoral student in the Department of Biomedical Engineering; and Frank Q. Zhu, a former doctoral student in the Department of Physics and Astronomy.

Regarding the faculty members’ participation, Chien led the group that developed the electric tweezers technique and collaborated with Levchenko on its biological applications.

The research was funded by the National Science Foundation and the National Institutes of Health.

Johns Hopkins Institute for NanoBioTechnology