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Living large studying the small
As told by Chad A. Mirkin

I was born in Phoenix, Arizona, USA in 1963, the youngest of four brothers. My father had a unique career path that spanned roles as a lawyer to an administrator in the Peace Corps and in multiple institutes of higher education to, ultimately, an administrative federal judge in the US Department of Interior. My mother, who played a significant role in shaping my identity, was a physical therapist. During my formative years, my family relocated frequently due to my father’s work, spending extended periods of time in Asia, especially South Korea and Malaysia.While in South Korea, my parents adopted my little sister.

My brothers (L-R) Adam, Andy, and Peter, my sister Miya, and me in the early 1970s

These experiences exposed me to diverse cultures and broadened my worldview profoundly. Throughout my childhood, my parents, and especially my father, encouraged a pursuit of knowledge for its intrinsic value rather than for material gain, fostering a passion-driven approach to life. They granted my siblings and me the freedom to explore our interests while underscoring the importance of hard work and education as prerequisites for success. To this day, my father’s extraordinary intellect remains a source of inspiration, and the invaluable lessons imparted upon me by my parents have guided my personal and professional endeavors.

High school graduation photo, 1982.

In many ways, I embody the traits often associated with the youngest child – I am a risk-taker and free-spirit. I never wanted to follow in my father’s or mother’s footsteps, nor did I want to play second fiddle to any of my brothers, who ended up as a surgeon, a geologist, and a physicist. I wanted to do something different – by default, that left chemistry. Later in my childhood, my family settled in rural Meyersdale, Pennsylvania – coal country, and I was provided ample opportunities for exploration and adventure. In high school, I spent more time playing sports, especially basketball, than I did thinking about science. Science wasn’t particularly emphasized or heavily resourced, but my high school did give away a science award, and my senior year, I won it. I am certain my class valedictorian deserved it, but they couldn’t give every award to him. Regardless, this recognition gave me confidence in my scientific abilities, drawing me deeper into the realm of technology and innovation, where I ultimately found my passion.

Discovering my passions and building lifelong connections
I attended Dickinson College in Carlisle, Pennsylvania, an ideal environment for my undergraduate studies. The liberal arts approach allowed me to explore many subjects, hone my writing skills, and establish life-long connections. It was there that I met Beth, who has now been my wife for over 30 years; she also was pursuing a degree in the sciences. After graduating with a BS in Chemistry in 1986, I pursued my PhD in Chemistry at Pennsylvania State University. Under the mentorship of Professor Greg Geoffroy, I worked in the field of organometallic chemistry, a discipline that involves the study of inorganic complexes with metal-carbon bonds. Completing my doctoral studies in a little less than three years, this period solidified my aspirations for an academic career and fostered lasting professional relationships.

One such connection was with SonBinh Nguyen, who has been a long-time colleague of mine at Northwestern University (NU); I mentored him while he was an undergraduate student at Penn State. In 1989, I embarked on a two-year stint as a National Science Foundation (NSF) Postdoctoral Fellow at MIT under the guidance of Professor Mark Wrighton. Regarded as a pioneer in inorganic photochemistry, Mark’s work in surface chemistry and soft microelectronics and microelectrochemical systems set the stage for the modern era of nanotechnology. My research involved the development of miniaturized electrochemical sensors for CO, and my postdoctoral projects gave me a strong foundation in surface science and electrochemistry. I must admit, at the start of my journey at MIT, I was intimidated by my peers, most of whom had “perfect academic pedigrees”. I wasn’t certain I could compete; but, as a friend of mine put it, “Everyone here puts their pants on one leg at a time; no one jumps off the dresser!” I quickly realized I was in my element.

Left: A chemistry class at Dickinson, 1986. Right: SonBinh Nguyen and me at our Schlenk line in the Davey laboratory at Penn State, 1988.

Much of my professional success can be attributed to Greg and Mark – they played instrumental roles in shaping my trajectory as a scientist. From them, I learned the intricacies of scientific inquiry and the art of communicating science well. They taught me how to identify a problem, break it down, and design the right experiments based upon a sound hypothesis in order to solve it. Mark has an incredible skill where he can take whatever data you have and immediately determine what is important and what isn’t. Greg and Mark, who both went on to become presidents of universities, are exemplary communicators. They emphasized the importance of tailoring scientific presentations to the audience, focusing on what the work means to them and its potential impact on their lives and fields.

Taking my career in a Northwestern direction
In 1991, at age 27, I launched my independent career at NU. I was thrilled to be in the company of top chemists like Mark Ratner, George Schatz, Bob Letsinger, Brian Hoffman, Fred Basolo, and Jim Ibers and in a department that had produced lauded chemists like Harry Gray and Ralph Pearson.As a young Assistant Professor, I was hungry to break new ground and chart new paths forward. At the same time, Beth and I were happy to be settling in the Midwest, and we started to raise a young family. I was busy at home and even busier in my career. My oldest child, Ben, got his first taste of nanoscience as an infant, playing on the floor of my office as I put the finishing touches on grant proposals and manuscripts. Interestingly, despite such opportunities to learn by osmosis, none of my children, Ben or my daughters, Sarah and Rachel, opted for science as a career. I like to believe such things skip a generation, so I expect my grandchildren to favor life in the lab!

New chemistry at the nanoscale
In 1996, a pivotal moment in my career unfolded during a colloidal crystallization seminar. Researchers were exploring methods for synthesizing colloidal crystals by relying on electrostatic attraction or small molecule interactions among particles. I envisioned a novel chemistry paradigm where nanoparticle “atom” interactions could be precisely controlled via high-information-content molecular “bonds.” However, the angstrom-sized small molecules being discussed and nanoscale particles are different in scale, and cross-reactivity is inevitable with such basic chemical interactions.

(L-R) Bobby Mucic, postdoctoral researcher Robert Elghanian, graduate student James Storhoff, Bob Letsinger, and me in the lab during my early days at NU.

"New and great things become possible when we meet people who share common goals and interests."

Contemplating this challenge, I proposed a new idea: harnessing short snippets of synthetic DNA (oligonucleotides), the blueprint of life, as a bonding agent and construction material. Its customizable length and sequence, and its ability to engage in highly specific interactions based on Watson-Crick base pairing presented an elegant solution to the issues of scale and cross-reactivity. Note that solid-phase oligonucleotide synthesis permits the rapid, tailorable production of diverse chemical forms of DNA in a single afternoon using automated instruments called gene machines. DNA was ideal as a source code and programmable adhesive for colloidal crystal engineering. This conceptual framework facilitated genuine parallels between particles and atoms and between molecular linkers and electron bonds—a notion that could redefine how we, as chemists, construct large swaths of matter.

The importance of collisions and connections
Chemistry, and life, is about collisions and connections. In chemistry, if atoms collide under the correct set of circumstances, new molecules and matter can form. It’s the same in life: new and great things become possible when we meet people who share common goals and interests. I wanted to know more about DNA, and fortunately, Bob Letsinger was a colleague of mine at NU. Bob pioneered the development of the chemical reactions that underpin current day gene machine instruments; thanks in large part to Bob and his former student, Marv Caruthers (now a Professor at University of Colorado), a researcher can now enter a desired DNA sequence, for example, into an instrument and obtain the strand a few hours later. I asked my new-at-the-time graduate student, Bobby Mucic, to reach out to him to learn how to make strands of DNA that could be chemically immobilized on gold nanoparticles. This ability, I thought, would allow us to make an almost endless number of programmable “atom” equivalents, or PAEs – in this case, different batches of gold nanoparticles with different sequences of DNA strands chemically affixed to their surfaces. If we designed the sequences to be complementary to one another, could sequence-encoded recognition be used to guide the formation of preconceived colloidal crystal structures?

Photo from 1996 of
DNA-modified gold
nanoparticles before (L) and
after (R) hybridization.
Taken from Chem. Rev. 105,
1547–1562 (2005).

In our initial experiment, when we mixed two batches of DNA-functionalized gold particles with a linker comprised of DNA that was partially complementary to each of the strands on the particle surfaces, we observed a striking red-to-blue color change. We later learned that the color of these materials is associated with the plasmonic properties of the gold particles, which change when they are brought in close proximity as DNA “bonds” are formed between them. When we raised the temperature of the DNA-linked particle aggregates above the melting temperature of the DNA duplexes, the solution turned red again, indicating that the gold nanoparticles were once again dispersed.In essence, we were visualizing the assembly and disassembly of the DNA double helices in the sample. We immediately recognized that this new class of sequence-encoded materials could be used to create new biological detection platforms and, as it eventually turned out, shots-on-goal for new nucleic acid medicines.

"SNAs have revolutionized aspects of materials chemistry and underpin many fundamental methods and processes in the burgeoning field of nanomedicine."

DNA-functionalized gold nanoparticles are one class of what is now termed spherical nucleic acids (SNAs); and SNAs are one class of PAEs, of which there are many types, including some that are not spherical but anisotropic in shape. SNAs can be made in many forms depending upon the chemical and physical properties of the nanoparticle core (composition, size, and shape) and nucleic acid strand (length, backbone type, and sequence). SNAs have revolutionized aspects of materials chemistry and underpin many fundamental methods and processes in the burgeoning field of nanomedicine. Indeed, SNAs are the prototypical PAEs and reshaping how we think about and teach concepts in traditional chemistry, especially in the context of nanotechnology.

New techniques, new territories
I’m generally an enthusiastic person but I get bored easily. I thrive on venturing into uncharted research territories. While many scientists are reluctant to venture far from their core training, I embrace it. Although my background is in synthetic organometallic chemistry, scientific principles transcend disciplines. Some of the most exciting discoveries happen when scientists and engineers cross boundaries between fields. Prior to arriving at NU, I had never worked with DNA; today, you’d be hard-pressed to find a time in my lab when our DNA synthesizers aren’t running.

In the late 1990s, DPN was used to write a portion of Richard Feynman’s speech "There's Plenty of Room at the Bottom: An Invitation to Enter a New Field of Physics," where he predicted the rise of the field of nanotechnology in text a one-molecule high.

In the late 1990s, shortly after launching my independent career, I utilized, for the first time, an instrument that would turn out to change the direction of my research: an atomic force microscope (AFM). Researchers use AFMs to scan a tiny, cantilevered tip across a surface to gather topological information about it. However, if used in air, water accumulates at the point-of-contact between the tip and the surface; this droplet hinders accurate measurements. In somewhat of a serendipitous discovery, we were the first to image the water droplet, the result of what people referred to as the capillary effect. Many considered the capillary effect a problem, but as a chemist, I viewed it as an opportunity – it’s about perspective after all. In 1999, I posed a question to my postdoctoral associates, Richard Piner and Seunghun Hong: what if the water droplet could be leveraged as a tiny reactor? What if, by preloading the tip with molecules, we could rely upon the solvent to facilitate their movement to and reaction with the underlying surface? These questions marked the inception and invention of dip-pen nanolithography (DPN), arguably the first form of nanoscale additive manufacturing. Initially, we used DPN exclusively as a molecular printing technique for patterning well-defined, nanoscale chemical and biological features that were one-molecule thick. It caught on and, shortly afterward, it became a mainstay of communities of researchers around the world who were interested in studying the consequences of miniaturization, or in other words, what happens when you shrink down ordinary materials (or collections of molecules), making them smaller and smaller. DPN has been instrumental in investigating molecular electronics, in controlling cell morphology, in influencing crucial cellular processes like motility and differentiation, and much more.

Decades later, the descendants of the original lithographic tools used for DPN are some of the most versatile and parallel chemical synthesis tools on the planet. What once involved just one or a few tips has evolved into systems with millions of tips. In 2016, we used such systems to prepare and introduce the concept of megalibraries – arrays of millions to billions of positionally encoded nanomaterials systematically varying in size and composition. In terms of feature size these libraries are nano-, but in terms of feature number and information content they are mega-; they dwarf the analogous arrays used to fuel the genomics revolution. A single library can contain over five billion unique materials.

(L, center) Optical microscope images of a 2.25-cm2 megalibrary of nanoreactors, showing patterns defined by individual pen tips and (R) electron microscopy image of AuPdCu nanoparticles after annealing the megalibrary, which contains 2.25 million distinct materials. Taken from MRS Bulletin 48, 1172–1183 (2023).

As such, when analyzed properly in high-throughput and especially when coupled with AI, megalibraries are being used to identify new materials important to the global clean energy transition, ones that catalyze important chemical processes, ones that enable new type of optical displays, and ones that improve the performance of battery technologies. These tools have transformed the way we study and understand the materials genome. Megalibraries are a great example of what can happen when you think big when studying the small: the concept of scale and what happens fundamentally as you transition between length scales is fascinating. Again, it’s all about perspective.

The house that nano built
Upon joining the faculty at Northwestern University (NU), I found myself at the cusp of the burgeoning era of nanoscience, an area that intrigued me as a young scientist. In 1998, Professor Mark Ratner and I persuaded then-NU President Henry Bienen to make a bet on nanoscience, effectively transforming NU into Nano U. This initiative led to the establishment of the International Institute for Nanotechnology (IIN), with Henry appointing me as its founding Director, a position I hold today. In 2003, the Center for Nanofabrication and Molecular Self-Assembly, now named Ryan Hall, opened its doors. It was the first federally funded facility of its kind and became a hub for global nanotechnology research on NU’s Evanston campus.

(L-R) David Kabiller (chair of the IIN’s Executive Council), my wife Beth, Pat and Shirley Ryan, and me. I owe a great deal to the generous donors, who are staunch supporters of nanotechnology and NU.

Riding the wave
The timing couldn’t have been better. In 2000, Clinton announced the establishment of the National Nanotechnology Initiative, the NNI, and the early advances by my group and the growing number of NU faculty emersed in nanoscience and technology research became the foundation for our receipt of a $50-million NSF Nanoscale Science and Engineering Center (NSEC). We were awarded the grant in 2001, and it ran until 2012. This center helped solidify NU’s reputation as a leader in nanoscience, but also, importantly, in collaboration and team science. Its support for educational programs also helped the IIN to initiate what would become a long history of funding students and postdoctoral fellows in nanoscience. Over the years, the IIN has run fellowship programs that have collectively trained close to 1,000 individuals from all over the world, a large fraction of whom have gone on to faculty positions at top institutions. Pat and Shirley Ryan and the Weinberg Family have been instrumental in this effort, through their establishment of fellowship programs for extraordinary, promising graduate students and postdoctoral fellows, respectively, in nanoscience. David Kabiller and the late Rosemary Schnell have also extended the IIN’s reach by providing resources for idea exchange, collaboration, research, and professional recognition. I am grateful to these individuals and honored to call them friends.

From bench to market and clinic
As we continued to develop crucial infrastructure, my work inside the lab was full steam ahead. Our invention of and initial observations with SNAs left us with more questions than answers, the absolute best situation for any scientist. Throughout the late 1990s and early 2000s, we began to explore and exploit the vast chemical landscape made possible with nanoparticle-oligonucleotide conjugates, creating new classes of SNAs and exploring their unique structure-function relationships. The discovery of enhanced, cooperative SNA binding properties marked the first signs of their translational significance in biomedicine.

An early Verigene system that was commercialized by Nanosphere, the first company I co-founded. The Verigene relies on gold nanoparticle-based SNA probes to detect DNA signatures of disease.

We developed a suite of extracellular diagnostic schemes for the detection of oligonucleotides, proteins, and other molecules, initially relying on visual or colorimetric readout. Before long, we developed more complex ones based upon signal amplification and surface enhanced Raman spectroscopy (SERS) and electrochemistry. Some of these detection systems displayed sensitivities and selectivities that rivaled or even surpassed the state-of-the-art at the time, ELISA- and PCR-based techniques. One of these extracellular diagnostic technologies based upon SNAs and silver amplification (the scanometric method), was commercialized by Nanosphere, the first company I co-founded in 2000.They commercialized the Verigene System, and today, this system can be found in many of the world’s top hospitals. Nanosphere was acquired by Luminex in 2016, which was subsequently acquired by DiaSorin in 2021.

In the mid-2000s, we envisioned the potential of SNAs for monitoring and then regulating what goes on inside living cells. However, it was well-established that negatively charged linear oligonucleotides do not effectively enter cells, which are also negatively charged, without the use of positively charged transfection agents (like-charge moieties repel one another, oppositely charged ones are attracted to one another). Such transfection agents are often toxic, which presents a major hurdle to the implementation of nucleic acid therapies. Yet through an experimental leap-of-faith, a Friday-afternoon exploration of the “impossible,” we made the surprising observation that SNAs, though negatively charged, naturally enter cells without the need for transfection agents. We proved later that this observation was due to the unique three-dimensional structure of the SNA. We later tracked the mode of entry of SNAs and determined that it was based upon scavenger receptor- and caveolin-mediated endocytosis – the SNAs interact preferentially with biomolecules on the surface of a cell membrane and are then internalized into the cells via vesicles, called endosomes.

A still image from an animation that shows SNAs being engulfed by a cell membrane. We found thatSNAs enter cells via targeting scavenger receptors and caveolin-mediated endocytosis. Credit: The Seagull Company.

Subsequent work went into measuring and identifying conditions for augmenting their release from endosomes into the cytoplasm. From there and into the late 2000s, we capitalized upon this finding to create SNA-based probes that could be utilized for intracellular mRNA detection at the level of single live cells – the NanoFlare platform, and SNA-based agents that could be used in gene regulation and later immunotherapy. These SNA-based intracellular diagnostic and therapeutic technologies have been the focus of multiple other companies that were co-founded by me, including AuraSense (2009), AuraSense Therapeutics (2011), Exicure (2012), Holden Pharma (2022), and most recently, Flashpoint Therapeutics (2023).

Our implementation of SNAs inside cells spurred the study of the internalization of all sorts of nanomaterials by research groups worldwide. The IIN collaborated with the Robert H. Lurie Comprehensive Cancer Center (LCC) to bring a National Cancer Institute (NCI)-funded Center of Cancer Nanotechnology Excellence (CCNE) to NU in 2005. We ultimately received all three phases of funding, bolstering a center that ran until 2021. Among other accomplishments, the CCNE took SNA drugs all the way from the bench to clinical trials for glioblastoma multiforme, an aggressive form of brain cancer, at NU’s Feinberg School of Medicine. Such success led to major philanthropic support from Ron and JoAnne Willens, Ed Bachrach, and others to support cancer nanooncology research at NU.

Going to Washington, DC…
In 2008, I received the $500,000 Lemelson-MIT Prize, followed closely by an even rarer achievement: becoming the 10th individual to be elected to all three US national academies – the National Academy of Engineering, the National Academy of Sciences, and the National Academy of Medicine – as well as the American Academy of Arts and Sciences. I take nothing for granted, and our success only made me want to work harder. I found myself, again, busy at home, but even busier at work. I had teenagers by then, and life was moving fast. My family and I are very close, and I enjoy spending time with them and our dogs, especially when traveling together and at our home in North Carolina. We recharge at the beach.

Members of President Barack Obama’s PCAST in 2017.

Simultaneously, in 2008, I received the rare opportunity to serve my country at the highest level. President Barack Obama appointed me as a Member of the President’s Council of Advisors on Science and Technology (PCAST), a role I held for eight years until 2016 through both of his terms. It was initially quite daunting – how could I use this position to positively impact science, not just in my own lab, but nationally and globally? I had to learn how to operate on a different level, but it wasn’t long before I began to see paths forward and, with the many other talented and savvy individuals on PCAST, we began to move toward positive change in many areas, including education, advanced manufacturing, and vaccine development.

The cover of the first issue of Small, highlighting our work in nanoelectronics. Dr. Peter Gölitz and I co-founded Small over a dinner at Dylan’s Steakhouse in New York City.

As a global ambassador and advocate for science, this position gave me immense access. I established important connections with researchers, government officials, and administrators in many areas of the world that were then beginning to heavily invest in science and technology. These connections led to global center development in nanomedicine and researcher exchange between NU and institutions in Europe, the Middle East, and Asia. I was even invited by Craig Mundie, another PCAST member who became a close friend, to speak at the Asia-Pacific Economic Cooperation summit in 2011, a gathering of world leaders from 21 countries, including President Obama and Secretary of State Hillary Clinton.

…and breaking down barriers
I don’t believe in barriers of any kind when it comes to science. I want the best and brightest researchers from all over the world working together with the best possible resources and facilities to solve the most pressing problems. Building and cultivating diverse teams are essential. My role on PCAST enabled a route for me to do that globally. I also established a foothold in scientific publishing as another way to drive the global conversation in nanoscience. I co-founded the journal Small with Dr. Peter Gölitz and Wiley in 2005, I served as an Associate Editor of Journal of the American Chemical Society for eight years, and I am currently serving my sixth year as an Editorial Board Member of Proceedings of the National Academy of Sciences.

Tiny structures, broad impact
SNAs are hugely impactful because they have implications across diverse fields. I mentioned their impact in medicine, biology, and the life sciences, but they are also very important structures in materials science. Starting in earnest in the late 2000s, my group, often times in close collaboration with colleagues like George Schatz, Byeongdu Lee, SonBinh Nguyen, Monica Olvera de la Cruz, Sharon Glotzer, and Vinayak Dravid, made important advances in colloidal science (the study of solutions of dispersed particles) that led to the rapid expansion of the burgeoning field of colloidal crystal engineering with DNA. In a 2011 paper in Science, we delineated a first set of design rules for preparing colloidal crystals using DNA programmable assembly. Since then, we’ve discovered new design rules and continued to refine existing ones. These rules are a roadmap for the preparation of tailorable, single-crystalline materials that are impacting catalysis and optics, making things like negative refractive index materials (materials postulated as the basis for invisibility cloaks) fact, not fiction. We are also writing a textbook that teaches these design rules. These concepts involving materials-by-design are so foundational that they can be taught in general chemistry courses. The design rules are akin to Pauling’s rules for preparing inorganic crystals, which provide the roadmap for understanding what crystal structures are expected given different ionic starting materials, but even more powerful in their predictive capabilities.

"These concepts involving materials-by-design are so foundational that they can be taught in general chemistry courses."

Something new, all over again
In the mid- to late-2010s, my group delved into another new area of nanomedicine – immunology and immunotherapy. At the time, researchers were becoming increasingly interested in figuring out how to use a patient’s own immune system to fight devastating diseases such as cancer. We had already discovered that the ability of SNAs to enter over 60 different cell types was based on their interactions with protein receptors imbedded within cell walls. Since we knew SNAs entered through endosomes and that toll-like receptors, or TLRs, proteins that control immunity, reside in the walls of endosomes, we postulated that we could design new classes of immunostimulatory SNAs that could interact with TLRs and that could serve as adjuvants in immunotherapy. We did just that, and later, we showed that SNAs prepared using nucleic acid adjuvants and peptide antigens could be formulated as highly potent vaccines. We found that the way that each of these components was displayed within the SNA structure markedly influenced its potency.

We established a new field of structural immunotherapy, which we coined “rational vaccinology”, where, by changing the orientation and arrangement of adjuvants and antigens comprising the SNA structure, therapeutic potency could be systematically increased. Rational vaccinology holds immense promise in pharma; we have developed SNA vaccines for many forms of cancer, and at the height of the COVID-19 crisis, my lab pivoted to develop an SNA-based vaccine for COVID-19. In certain cases, SNA immunotherapies have been shown to be curative in patients (for example, those with Merkel cell carcinoma, a deadly form of skin cancer). Recently, we also introduced the concept of CRISPR SNAs, structures that broaden the applicability of gene editing by significantly expanding cellular and tissue access.

Left: Electron microscopy image of nanoparticle crystals. Taken from Nano Lett. 18, 6022-6029 (2018. Right: Our lab has developed the technology behind printers for the fabrication of materials, from the very large to the very small - Azul3D’s LAKE 3D printer and TERA-print’s M-series, respectively.

Leading the tech transfer charge
The flood of scientific discovery led to inventions across the fields of medicine, biology, clean energy, and advanced manufacturing. Soon, the IIN became a tech transfer hub and an incubator for ideas and intellectual property for start-up companies. Some of our discoveries have transcended the field of nanotechnology to areas in which we originally had very little interest. My 400th issued patent is a prime example. It describes high-area rapid printing (HARP), a 3D printing technology that is being commercialized by Azul3D. The printers being produced by Azul are changing the way aspects of manufacturing are being done and are some of the fastest and largest in the field. It’s ironic that, when we invented HARP, we were trying to make the world’s smallest 3D printers.

"It’s ironic that, when we invented HARP, we were trying to make the world’s smallest 3D printers."

We were exploring the use of fluorocarbon oils to keep polymerized resin from sticking to the tiny tips used in the nanolithographic printers that I described above. We quickly realized that such a strategy would also work with macroscale 3D printing by keeping resin from sticking to the part being printed, allowing rapid continuous printing. Moreover, if the oil was flowed over the interface and circulated through a cooler and filter, we could actively eliminate the heat generated through the exothermic polymerization reactions – the biggest issue limiting large area 3D printing. In my lab, we now could span over 18 orders of magnitude in volumetric printing capabilities – from the nanoscale to the macroscale. We had brought our exploration of scale full circle – going from big to small to big again.

Educating the next generation of scientists
Along with the development of core scientific principles and translated products that people now use globally, my students are my most important and lasting professional legacy. Over 340 graduate students and postdoctoral fellows and hundreds of undergraduates have been trained in my lab. Over 140 of these people are now university professors around the globe, charting their own scientific paths, and many are leaders in industry. Although we have been prolific, I am most proud of a few of our papers that have marked inflection points in scientific thinking and translational efforts. I also enjoy teaching, especially general chemistry, which I have taught throughout most of my Northwestern career. I love it – each time I teach the class, I learn something new, and I love the excitement and lack of cynicism that the freshmen bring to class. I’ve always integrated modern chemical research and nanotechnology concepts into my classes, and my message is clear, if you choose a path in science, it will be intellectually challenging but one of the most rewarding things you ever do – you won’t regret it!

Our research group in late 2023.Credit: Matthew Gilson Photography.

You are only as good as those who surround you
I was fortunate to encounter early in my career true champions of my work, including many colleagues (some of whom I’ve mentioned), professors like Gerald Roper at Dickinson College, who encouraged and challenged me in new ways, and program officers like Dr. Hugh De Long, who I first met by chance on the San Antonio River Walk during an Electrochemical Society Meeting.At a time where reviewers were less than kind and I had very little research support, he believed in the potential of what we were doing. He gave me my first AFOSR grant, and we established a 30-year relationship that continues today. He helped me forge connections throughout the DoD and government that generated enormous investment in my research program and, sometimes, less-than-mainstream ideas. I would not be where I am today without their support and collaboration.

Not everyone was a fan though – indeed, I have learned you must be resilient, tough-skinned, and capable of taking criticism to succeed. Many years ago, I received a less-than-complementary review that questioned the contributions we had made and suggested that the federal government should not invest another dollar in our research. I posted that review on my office door as a personal motivator and also so every student could see that success doesn’t come without doubters. Life, especially as an academic, can be a bruising business. If you don’t believe strongly in your own work, you will never convince others to believe in it. I teach this lesson to my biological as well as academic kids.

"I have learned you must be resilient, tough-skinned, and capable of taking criticism to succeed."

I celebrated my 60th birthday last year, and I'm embracing this phase of life with excitement. I am ecstatic that all of my children settled in the Chicago area after completing college. My eldest daughter recently tied the knot and is thriving as an elementary school teacher. My son and I co-founded a company called TERA-print; he leads business development, while my other daughter contributes her skills to law enforcement. Every day, I'm invigorated by the dynamism of my colleagues, collaborators, trainees, and staff. They inspire me, often pushing me to achieve more than I imagined. I am fortunate to feel like I haven’t worked a day in my life – it feels more like play.I can’t wait to see where nanoscience leads me until one day, as Harry Gray, my academic grandfather, would say, I am rolled out of my office “feet first but fully funded.”

Acknowledgement: I acknowledge Dr. Sarah Hurst Petrosko, Research Professor and IIN Associate Director, for assistance in editing this piece.

My family and me at my daughter Sarah’s wedding in December 2023.