Three cutting-edge researchers – Maartje Bastings, Romain Fleury and Guillermo Villanueva – have joined the School of Engineering as tenure track assistant professors (PATTs). Their research interests include DNA-origami nanoparticles, artificial materials for guiding waves and planting spies in cells.
The School of Engineering welcomed three new tenure track assistant professors (PATTs) at the start of this year. Maartje Bastings joined the Institute of Materials, Romain Fleury took up a post in the Institute of Electrical Engineering, and Guillermo Villanueva has moved to the Institute of Mechanical Engineering.
Maartje Bastings, Programmable Biomaterials Laboratory
DNA as material for building customized nanoparticles
Maartje Bastings, who came from a postdoc at Harvard, has developed strategies to use DNA as a material for therapeutic nanoparticle engineering. DNA is typically used as a source of genetic information but is also an extraordinary building material. Scientists can use it to set the size, shape, and structure of nanoparticles with extreme precision.
DNA strands are made from four nucleotides: adenine (A), cytosine (C), guanine (G) and thymine (T). The order in which these nucleotides appear is what defines a DNA sequence. Nucleotides naturally pair together: A with T and G with C. By selecting a desired sequence length and leaving the pairs to form themselves – as if they were ‘folding’ together – scientists create DNA-origami. The challenging part was to make these nanoparticles stable in a cellular environment. "We discovered a way to program and build customized nanoparticles and add ligands in specific places, and to protect the final structure against destructive conditions found in cell medium, cells and tissue. This opens the door to many potential therapeutic applications," Bastings said.
Creating vaccines and artificial organs
Using this breakthrough process, Bastings built a nanocapsule for delivering therapeutic agents to targeted cells. She also successfully provoked an immune response from cells in vitro, just like vaccines do. This multimodal targeting is very difficult with conventional nanoparticles, since the cell surfaces are complex and packed with different sensors. "The advantage of using DNA as building material for nanoparticles is the perfect uniformity and control over complex ligand presentation", Bastings says.
The researcher also plans to use her origami nanoparticles to grow stem cells and generate artificial tissue. "These cells need to feel ‘at home’ in order to grow, otherwise they die. Incorporation of our programmable DNA nanoparticles into a polymer material matrix could send them just the signals they need," she says. Stem cells are currently placed in expensive hydrogels and matrices derived from cancer tissue (carcinoma). "All the right ingredients are in the hydrogels but we don’t really understand what’s going on, which signals are important for proliferation and adhesion. With our nanoparticles, we can create an analytical toolbox, monitor and trace each one, and find out exactly what’s happening. This will help us learn a lot more about how these cells work."
Bachelor, Master and PhD degrees from Eindhoven University of Technology
Internships at Caltech and the University of California, Santa Barbara
Postdoctoral Fellow at the Wyss Institute at Harvard University
Romain Fleury, Laboratory of Wave Engineering
Cross-cutting wave research
Romain Fleury, who now heads EPFL’s Laboratory of Wave Engineering, studies wave phenomena in the broad sense. His focus is on developing unusual concepts relating to any kind of waves and then applying those concepts across a range of disciplines. For Fleury, there are no boundaries between seismic, electronic, optical, and acoustic waves.
Fleury’s research investigates in particular metamaterials (artificial materials) in particular and their ability to guide waves. For instance, topological insulators – a discovery that won the 2016 Nobel Prize in Physics – have super-conducting properties on the surface and insulating properties inside. Electrons move along the surface with almost zero resistance and in a single direction unfazed by obstacles, as if on a one-way road. "We wanted to know if the behavior of electrons – which act as both waves and particles – could also apply to electromagnetic waves, provided we find a way to reproduce their spin. And we found that it is indeed possible," Fleury said.
The potential is enormous. "Electromagnetic waves typically bounce off matter, losing energy. But we are able to guide waves in a single direction and with almost no losses." A telecommunications startup has already licensed the patent that Fleury filed and hopes to use it to double the speed of 4G communications. "Today’s smartphones send data on one frequency and receive it on another. But if the waves are carefully guided, both signals could travel on the same frequency without overlap. That will let telecom companies optimize their bandwidth," Fleury said. Other possible applications include future optical computers, nanophotonics, and guiding light waves or vibrations and concentrating them on a specific point.
Making things disappear
Another interesting application involves using 2D materials to slow down light waves. Slow waves, which interact more strongly with molecules, could be used for such things as carrying out DNA sequencing or detecting specific compounds.
Fleury is also looking at developing a material that could be used to cloak objects and make them undetectable by radars and sonars – or even invisible to the naked eye. "Making a person invisible, like Harry Potter’s cape does, would be extremely difficult. Our technology is intended more for objects like drones and airplanes."
The Laboratory of Wave Engineering is currently seeking PhD students.
Bachelor and Master degrees from the University of Lille, France
Master’s project at EPFL
PhD from the University of Texas at Austin
Postdoctoral research at the École supérieure de physique et de chimie industrielles (ESPCI) Paris
Guillermo Villanueva, Advanced NEMS Laboratory
Developing sheets of highly sensitive sensors
Guillermo Villanueva, previously an SNSF-funded professor at EPFL, is now studying ultra-small resonators for a whole new approach to detection and communication.
The resonators (NEMS or nano electromechanical systems) that Villanueva develops are about one micron long and a few nanometers thick and can be tuned to a given frequency like guitar strings. This makes them effective sensors with highly precise detection capabilities: their shape and resonant frequency changes if, for example, a mass (such as a molecule) comes into contact with one of these nanostrings, if there is moisture in the air or if there is a temperature change. Most of Villanueva’s resonators are made from a piezoelectric material, meaning they send out electric charges when they change shape. The sensors thus provide information on both their electrical and mechanical properties.
Villanueva also plans to use 2D materials like graphene and molybdenum disulfide (MoS2) to make entire sheets of these sensors. These surfaces would be just a few atoms thick and highly sensitive, enabling them to detect even the tiniest mechanical variations caused by molecules.
Planting spies inside cells
Thanks to their small size and other properties, Villanueva’s resonators could be used for more than just detecting gases or other compounds. One idea is to place them inside cells as spies to evaluate the cells’ mechanical properties.
By giving these spies a specific resonance frequency, they could track individual cells. "That’s already done with fluorescent substances, but the effect fades as cellular division takes place. Our resonators would remain inside the original cell," says Villanueva. So where does all this lead? "We could track diseased cells, study how metastases form and learn more about cell dynamics in human bodies."
Bachelor’s and Master’s degrees in physics from the University of Zaragoza
PhD degree in electrical engineering from the Autonomous University of Barcelona
Postdoctoral research at Caltech, the Technical University of Denmark and EPFL