Customized Deep Eutectic Solvents for Biocatalysis

Chemical industries are currently facing the challenging transition from the classic manufacture of petroleum-based chemicals to the sustainable synthesis of bio-based products in the spirit of a circular bioeconomy. With their outstanding efficiency, selectivity, and very mild reaction conditions, enzymes play an increasing role in the industry. With these strengths, biocatalysis has found its place among the complementary catalytic methods of today’s green chemistry. Eight researchers from Germany and Austria have joined forces within the framework of DFG Research Unit 5730 to investigate the use of application-specific tailored solvents to boost the sustainability and efficiency of enzymatic processes.

Deep eutectic solvents (DESs) are a very potent class of solvent systems that offer a variety of advantages in (bio)chemical conversions due to their specific properties. DESs are composed of mixtures of individual substances, which, when combined, are characterized by a considerable depression of the melting point, and the resulting liquid form is consequently structurally different from classic molecular systems. These differences in solvent behavior are particularly advantageous in biocatalysis, as they may enable higher enzyme stabilities and activities, among others. The ample design space for generating application-specific DESs, including the selection of individual components and the adjustment of water content (critical for enzyme catalytic performance and viscosity reduction), enables the development of solvents capable of solubilizing high concentrations of substrates and products, stabilizing/activating enzymes, while also facilitating downstream processing tailored to specific applications. DESs can thus make a crucial contribution to widening the scope of biocatalysis as a sustainable technology.

The main hypothesis of DFG Research Unit 5730 “Customized Deep Eutectic Solvents for Biocatalysis – a circular approach from molecular interactions to process parameters – DESMOL2PRO“ is that DES will fundamentally affect two critical aspects of bioprocesses, namely the reactivity and stability of biocatalysts and downstream processing. Developing and intensifying bioprocesses, therefore, requires a different approach than classical processes using aqueous, organic, and multi-phasic systems and, most importantly, requires seamless integration of various disciplines. The DESMOL2PRO explicitly addresses these two aspects by taking a holistic circular approach to understanding and then developing efficient and sustainable processes. The circular strategy will lead to gaining a deep understanding while designing from molecules to processes and vice versa.

All decisions for using application-specific DESs in biocatalysis must be included in an integrated process design, which comprises the theoretical, synthetic, and engineering research areas. This is made possible by a combination of investigation methods in the areas of computational fundamentals on the behavior of DESs and interactions with the protein (Computational Unit), the study of enzymatic catalysis in tailor-made DESs (Biocatalysis Unit), and the development of process control including downstream processing (Engineering Unit). As the chosen research approach requires close interdisciplinary cooperation between experts from modeling, catalysis, technical chemistry, and process engineering, a diverse team of scientists from different locations and with complementary competencies has been assembled for this research project.