"Thanks to the Ramón y Cajal Grant, I Can Open New Lines of Research on the Interactions between Light and Matter"

IQS researcher Dr Roger Bresolí Obach received one of the prestigious Ramón y Cajal grants awarded by the Spanish Ministry of Science, Innovation, and Universities – State Research Agency to promote the incorporation of research personnel with outstanding career tracks into national research organizations to gain skills and capabilities that allow them to establish themselves within the Spanish Science, Technology, and Innovation system, especially those who have undertaken research activities abroad.

Dr Bresolí has joined IQS – URL within the AppLightChem research group, where he carries out his cutting-edge research in the areas of photobiology, photochemistry, photonics, and optical materials. We recently talked to him about this important grant he received and his lines of research.

Roger, what does it mean to you and your career to have earned this Ramón y Cajal grant?

First of all, I am very grateful to the State Research Agency (AEI) for having awarded me one of the Ramón y Cajal grants. It is one of the most competitive and significant grants, which are awarded for a period of five years and give us a lot of stability as researchers. In my case, it allows me to advance within IQS – URL as a researcher and be able to carry out my own projects while giving me the opportunity to continue training as a professor and be able to teach certain subjects such as Thermodynamics and Kinetics, within the Bachelor’s Degree in Bioengineering, or Physical Chemistry, within the Bachelor’s Degree in Pharmacy.

As a researcher, what is your line or lines of research?

I am a member of the AppLightChem group at IQS, led by Dr Santi Nonell, who was the director of my doctoral thesis. This group has been working for a long time on lines of research on the use of light in chemical and medical applications, especially in photodynamic therapies (PDT), which is a commitment to the future and very important in the field of healthcare. I joined IQS and this research group again in 2022 thanks to one of the Beatriu de Pinós grants, awarded by AGAUR, which I had to give up when I received the Ramón y Cajal grant in January 2023. I had previously worked with Dr Johan Hofkens’s group at the Katholieke Universiteit of Leuven, where I specialized in advanced optical microscopy techniques.

Now, thanks to this Ramón y Cajal grant, I have been able to start my own projects and open new lines of research at IQS, which I find very interesting, such as the study of Light Matter Interaction. In the project I’m leading, ChemPhot, Chemistry of Photons – From Photobiology to Optical Matter, I am seeking to vindicate the central role of Chemistry as a link between the different fields of matter, from Biology to Physics.

“En el proyecto ChemPhot busco reivindicar el papel central de la Química como nexo de unión entre los diferentes campos de la materia”

What are your specific goals?

In the end, we want to understand the interaction between photons and matter in different areas of knowledge. For example, in photodynamic therapies, where there are molecules capable of absorbing photons to generate highly energetic excited states and transfer this energy to other molecules, such as oxygen, to generate cytotoxic species, such as singlet oxygen, or other reactive oxygen species (ROS). Due to their great oxidative potential, these species are capable of causing oxidative damage and, therefore, the cell death of pathogenic species, such as cancer cells or bacteria.

Another very interesting field is optical microscopy techniques, where we can use photons to visualize chemical and physical phenomena that happen at the nanoscale and be able to have as much information as possible. Because, if we can visualize a phenomenon, this will be the best way to study why it happens and understand the underlying phenomenology. In the end, we’ll make the popular saying true: “a picture is better than a thousand words.” This was the line I began to explore at the Katholieke Universiteit of Leuven with Dr Hofkens’s group.

“Through optical microscopy we can use photons to visualize physical and chemical phenomena at the nanoscale”

But the interest in photons goes even further due to their dual property of being waves or particles, as we already studied in high school. Thanks to this duality, photons have an associated moment and, therefore, when they interact with other particles, they can transmit this moment to them and induce forces, which are known as optical forces, a discovery for which the 2018 Nobel Prize in Physics was awarded to Dr Arthur Ashkin. If we combine these forces, we can generate clusters of nanoparticles with new and very interesting properties and thus enter another field, that of “optical matter” and metamaterials.

With that in mind, are you connecting the interaction of photons and matter?

Yes, because a new field of experience is opening up here that is known as the formation of metamaterials, which are nothing more than assemblies of different particles with a certain order that gives them special properties that they could not have by themselves individually. We can say that these are artificial materials with unusual electromagnetic properties that come from the design of the structure and the interaction between the different neighbouring elements. Despite everything, their chemical composition is still very relevant since it will determine the possible interaction between neighbouring elements.

“Metamaterials are nothing more than assemblies of different particles with a certain order that gives them special properties”

One type of these metamaterials is what is known as “optical matter,” in which different particles are joined by means of so-called optical binding. Just as a chemical bond can be described as the transfer or sharing of electrons, an optical bond can be seen as the sharing of photons between two particles by means of light dispersion processes. This area of knowledge is the heart of the Lightcompas project, a project funded by the State Research Agency within the Quantum Physics Panel, coordinated with other researchers from the Autonomous University of Madrid and the CSIC, of which I am the principal investigator. The objective of this project is to develop these “metamaterials” or optical materials generated on a surface, and to develop conceptual models and computational tools that help us understand all the phenomenology that arises from the interaction between light and matter.

Besides Lightcompas, are you working on any other projects related to metamaterials?

Yes, within this area of knowledge I am also a member of FASTCOMET, a consortium of six European research centres and universities with the aim of developing new data storage systems based on colloidal memory technologies and establishing a proof of concept. The idea is to be able to develop two different types of particles with antagonistic dielectrophoretic properties. Once we get them, we will be able to selectively trap these particles by applying dielectrophoretic forces and storing specific sequences. We expect to achieve information storage densities up to 1,000 times higher than current technologies. This is a pioneering project in Europe.

This November, the FASTCOMET consortium held a follow-up session here at IQS, where we presented the results achieved in this first year of work.

I would also like to add that I recently talked about metamaterials, their properties, and the FASTCOMET project on theIndefugibles podcast led by Dr Xavier Casanovas and Dr Oriol Quintana, professors with the Department of Ethics and Christian Thought at IQS.

What specific applications does your research bring to the table?

We have started talking about PDT, one of the star investigations of the AppLightChem group. PDT is being established as an alternative therapy to traditional ones (antimicrobial treatments or cancer treatment therapies), and is beginning to be used in clinical practice since some photosensitizers have been approved for clinical use both by the FDA and the European Medicines Agency (EMA) as second lines of treatment when chemotherapy fails. Due to its mechanism of action, PDT can improve or overcome certain resistance when the usual treatments fail, as well as the multiresistance of some bacteria, one of the main health problems of the future, or when tumour cells resist dying.

“Metamaterials are a commitment to the future that could improve the quality of life and comfort of citizens”

What can you tell us about metamaterials?

Metamaterials are truly a commitment to the future where we can find applications such as the development of new data storage systems, which can improve the memory capacity of devices with higher memory density and more powerful capacity than what is currently available, or materials with unconventional optoelectronic properties such as refractive index less than 1, super black materials, or materials with high electronic mobilities.

Current knowledge about optical metamaterials is in its infancy, but I am very confident in its potential. I hope that it will unfold like it happened with the development of laser technology in the 60s and that, over the years, these new materials will evolve from a scientific curiosity to being used daily to improve the quality of life and comfort of citizens.