The novel biocatalyst material is made up of two different proteins that self-assemble to form a hydrogel. Image: Graphics: Theo Peschke, KIT.
The novel biocatalyst material is made up of two different proteins that self-assemble to form a hydrogel. Image: Graphics: Theo Peschke, KIT.

Industry consumes large quantities of crude oil as raw material for the production of drugs, cosmetics, plastics and food, and the conventional catalytic processes that transform the oil into these substances consume a lot of energy and create waste. Biological processes with enzymes would be far more sustainable, as they can catalyze various chemical reactions without the need for auxiliary materials or solvents.

But enzymes are expensive and, hence, have so far been economically unattractive. Now, though, researchers at Karlsruhe Institute of Technology (KIT) in Germany have developed a new biomaterial that considerably facilitates the use of enzymes for industrial production. The researchers report their work in a paper in Angewandte Chemie.

Synthetic catalysts that speed up reactions are of critical importance to the chemical industry, being employed in about 90% of all chemical processes. Scientists at KIT have now developed an environmentally friendly catalytic biomaterial that could help to reduce energy consumption.

"In the long term, such biocatalytic materials are to be used in automatic production of value-added basic compounds without complex synthesis and cleaning steps and with a minimum amount of waste arising," says Christof Niemeyer of KIT's Institute for Biological Interfaces.

For this purpose, the scientists modified two enzymes so that they naturally self-assembled to form a stable biocatalyst. Similar to a two-component adhesive, the enzymes form a gel-type material, which is applied onto a plastic chip with groove-shaped depressions. As it dries, this enzyme material turns into a hydrogel.

The scientists then cover the plastic chip in a plastic foil and pump the raw materials through the grooves for the biocatalyst hydrogel to convert into the final products. No solvents or high temperatures and pressures are needed, which makes the process highly sustainable and environmentally compatible.

Due to the comparatively large reaction volumes, conversion rates in such miniaturized flow reactors or small reaction vessels are very high. Their use in biocatalytic processes, however, is still in its infancy, as carrier materials have always been required to fix the enzymes in the reactor. These carriers need reactor space that is then no longer available for the biocatalyst.

The new biomaterial, by contrast, adheres to the carrier, and so the reactor can be filled with a maximum amount of biocatalyst. Moreover, the biomaterial can be recycled, is biodegradable, highly stable, and reaches extremely high yields in reactions.

Compared to synthetic catalysts, biocatalysts are particularly advantageous when so-called enantiomers are produced by a process. These are compounds with molecular structures that are mirror images of each other. As a rule, only one of the compounds is usually wanted, as the other one generally doesn’t produce the desired effect or may even be toxic. Biocatalysts can produce specific enantiomers, whereas chemical processes often require expensive auxiliary materials for this purpose or for separating the two enantiomers.

This work was carried out under the framework of the Helmholtz Program ‘BioInterfaces in Technology and Medicine’ (BIFTM). "Our research and development work was possible only with the equipment and infrastructure of this program," says Niemeyer. Under this program, scientists at KIT cooperate across disciplines to study and use biological systems for applications in the industrial and medical bioengineering sectors. High interdisciplinarity requires broad methodological expertise covering materials production and characterization, as well as data-based simulation methods.

This story is adapted from material from KIT, with editorial changes made by Materials Today. The views expressed in this article do not necessarily represent those of Elsevier. Link to original source.