Julián Valero Moreno, iNANO, Aarhus University

Host: Professor Brigitte Stadler

Chemically Enhanced RNAs: bridging biomedical and nanotechnology applications
Replicating the sophisticated functions of proteins using synthetic molecules in complex biological environments, such as living cells, remains one of the grand challenges in chemistry. While man-made molecular systems have shown promise, their performance in cellular and in vivo contexts still pales compared to their natural counterparts.
My research revolves around the design and development of advanced nucleic acids with enhanced chemical stability, structural complexity, and functional diversity. The goal is to create synthetic molecules that can effectively mimic intricate biological functions. To achieve this, we are developing a versatile platform that integrates novel bioconjugation strategies, in vitro selection techniques, and RNA nanotechnology. This approach enables the construction of multivalent, chemically modified RNA molecules with potential applications in biomedicine and nanotechnology.
A key area of interest involves engineering RNA aptamers and other synthetic biomolecules functionalized with diverse ligands for precise protein recognition and targeted cellular regulation. Through this work, we aim to bridge the gap between synthetic and natural biomolecular systems, paving the way for innovative therapeutic and diagnostic tools.

Fabian Mahrt, Chemistry, Aarhus University

Host: Professor Brigitte Stadler

Phase state of atmospheric aerosol particles: Measurements & implications
Aerosol, tiny particles with sizes typically at the nano- to micrometer scale, are ubiquitous in the atmosphere. They play an important role for atmospheric chemistry, and contribute to poor air quality, affecting public health. Aerosols also critically impact climate, directly by scattering radiation and indirectly by acting as nuclei for clouds. Secondary organic aerosols (SOA) constitute the most abundant atmospheric particle type by mass. SOA particles form within the atmosphere from reactions of volatile organic compounds (VOCs), emitted from anthropogenic and biogenic sources, with atmospheric oxidants, including ozone, hydroxyl and nitrate radicals. Depending on their composition, as well as the ambient temperature and relative humidity conditions, the phase state of SOA particles can vary from a liquid, to an amorphous semi-solid, to a glassy phase state. As an example, glassy particles are thought to promote ice cloud formation by providing a solid surface for ice nucleation to take place, thus impacting climate.
While the importance of aerosol phase state in the environment is well recognized, it remains insufficiently understood for SOA particles, largely due to their chemical complexity and variety of combinations of different VOCs and oxidants from which they form.

The research presented here focusses on the phase state of SOA particles emitted by wildfires, that considerably impact air quality and climate and that have surged in frequency and intensity over the past years. By combining microscopy and fluid dynamic simulations, we directly quantify the humidity-dependent phase state of individual SOA particles. Our results show that the phase state of SOA particles is a strong function of relative humidity and for a given VOC, depends on the oxidant. We also present surprising evidence from X-ray diffraction that some SOA can exist in a crystalline solid phase state. Such SOA could represent an unrecognized source of nuclei for ice clouds.
Overall, our results shed new insights into the phase state of organic aerosols and highlight possible implications for cloud formation and climate.