Researcher Justin Zoppe wins an ERC Consolidator Grant to develop new chiral metamaterials

Montage of the property of chirality, the subject of Justin Zoppe’s research. It shows the researcher holding a model of glucose, the basic unit of cellulose.

Montage of the property of chirality, the subject of Justin Zoppe’s research. It shows the researcher holding a model of glucose, the basic unit of cellulose.

An expert in cellulose chemistry

Justin Zoppe (Michigan, United States, 1983) has been teaching at the UPC since November 2020. He received a bachelor’s degree in Chemistry (with honours) with a minor in Mathematics from the University of North Carolina Wilmington in 2005. He developed his doctoral thesis on the surface modification of nanocellulose substrates at the Department of Forest Biomaterials of North Carolina State University, from which he obtained his doctoral degree in 2011.

Throughout his career, he has worked as a postdoctoral fellow at the University of Aalto (Finland) and at the Swiss Federal Institute of Technology Lausanne (Switzerland) co-funded by a Marie Skłodowska-Curie Action.

In 2017 he received an Ambizione grant from the Swiss National Science Foundation, which allowed him to lead a research group on polymer chemistry at the Adolphe Merkle Institute of the University of Fribourg (Switzerland) until 2018.

Justin Zoppe is one of the few researchers in the world with combined expertise in cellulose chemistry, polymer grafting and colloidal assembly. With two-million-euro funding over five years, the Consolidator Grant will help him to pursue his research on new helicoid metamaterials templated by cellulose nanocrystals with end-tethered polymers.

The European Research Council has awarded a Consolidator Grant to UPC researcher Justin Zoppe from the Materials Science and Engineering Department to develop new metamaterials for detecting molecular chirality. The researcher will receive funding of two million euros to conduct the study over five years.

Mar 23, 2023

Chirality is a physical property of an object that is non-superposable on its mirror image. For instance, the right hand is a non-superimposable mirror image of the left hand. They have the same molecular formula, but different three-dimensional structures.

Detecting chiral structures with chiral spectroscopy is fundamental in chemistry, biology and the pharmaceutical industry, as it provides important information about protein secondary structures, electronic transitions and small molecule conformation. However, detecting molecular chirality is very difficult, since the resulting spectrometer signal is so weak that the differences in molecular structure are hard to identify.   

To move forward in this field, the European Research Council has awarded a Consolidator Grant to Justin Zoppe, a researcher of the Polyfunctional Polymeric Materials research group (POLY2) and a Serra Húnter lecturer at the Department of Materials Science and Engineering of the Universitat Politècnica de Catalunya - BarcelonaTech (UPC), teaching at the Barcelona East School of Engineering (EEBE) and the Barcelona School of Industrial Engineering (ETSEIB).

Specifically, the researcher will develop new metamaterials—materials engineered to have a property that is not found in nature—with the potential to increase spectroscopic sensitivity to distinguish molecular chirality. These helix metamaterials will be produced using cellulose—a polysaccharide extracted from paper, cotton or other plant fibres—which will be applied a hydrolysis treatment to obtain cellulose nanocrystals, to which synthetic functional polymers will be end-tethered. Such modified nanocrystals will be used as templates for the fabrication of metallic metamaterials.

A paradigm shift in metamaterials
According to Zoppe, “the most interesting thing about these cellulose nanocrystals is that they are self-assembling liquid crystals: when dried, they self-assemble into helicoidal structures.” The novelty of the study lies in modifying the ends of the nanocrystals to attach synthetic functional polymers that will be used as templates for the fabrication of metallic nanohelicoids.

As a result, “a film will be obtained that can be impregnated with metals, such as gold, which will be immobilised at the ends, where the functional polymers are,” explains the researcher, highlighting that “after crystallising the metal and removing the modified cellulose template, the ultimate goal is to achieve a new metallic helical structure, similar to a nanoscale Archimedes screw.” It is a pioneering procedure, so far researchers haven’t been able to produce such complex metallic structures through self-assembly.

The resulting structure will also be chiral and will exhibit extraordinary electromagnetic properties not observed in nature, which will improve chiral molecule detection in several fields of research. When combined in a solution of chiral molecules, they will act as a chiral communication vehicle between chiral light and small chiral molecules, amplifying the overall detection signal in chiral spectroscopy, such as circular dichroism.

These new metamaterials will be applied to a wide range of fields: chiral optics, nanodevices, machines, chiral sensors, biology and the pharmaceutical industry. They can also be applicable to future devices for invisibility cloaking and lenses for super-resolution imaging in natural sciences and in healthcare.

Based solely on self-assembly, the proposed engineering process represents a paradigm shift in metamaterials research and production, since it would simplify chiral metamaterials manufacturing, currently relying on complex and costly vacuum vapor deposition processes.  

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