From the laboratory to the consumer

SilicaCoat paper: a sustainable coating for products such as paper cups

Whether for packaging, disposal crockery or drinking straws, the current trend is to use paper instead of plastic to produce these products. In contrast to plastic, however, this cellulose material macerates in contact with water. TU researchers headed by Professors Dr. Annette Andrieu-Brunsen and Dr. Markus Biesalski (both from the Department of Chemistry) have been able to prevent precisely this problem using a sustainable coating made of silicon dioxide, the same substance that is also found in quartz sand. “In principle, we are combining two natural minerals to create a water-repellent paper”, says TU chemist Nicole Rath, who coordinates the Pioneer Fund project together with her colleague Dr. Maximilian Nau.

Due to its low thickness of less than 100 nanometres, this innovative coating is flexible and neither visible nor perceptible to touch. It is applied by submerging the paper in an aqueous solution of a substance that is chemically related to silica. Under the influence of acid and heat, a protective coating of silicon dioxide – which has been named SilicaCoat – forms on the paper.

Paper used for disposal cups and similar products has been coated with a thin plastic film up to now. According to Nau, this plastic film has caused problems during the recycling process but there are no such issues with the silicon dioxide coating: “Nothing is left on the paper except for a little sand.”

In their Pioneer Fund project that started in January, the chemists at TU Darmstadt want to test possible future applications and develop demonstrators and prototypes. Disposable crockery, packaging and baking paper, as well as membranes for technical applications, could also be produced using this innovative solution. However, some questions related to the commercial application of the method still need to be clarified such as how to coat different grades of paper. However, Rath and Nau emphasise that the main focus of the Pioneer Fund project is the practical implementation of the research. They want to use the funding to bridge the gap between academic research and commercial application and create the basis for a spin-off company.

APTASENSE: A quick test to identify antibiotics in food

Antibiotics are not only used in factory farming to combat diseases but also to increase meat production – a highly questionable practice that promotes antibiotic resistance. Consumers are not able to ascertain whether they are purchasing products contaminated with antibiotics. Researchers headed by Professor Dr. Beatrix Süß (Department of Biology) and Professor Dr. Heinz Koeppl (Department of Electrical Engineering and Information Technology) are developing a quick test to identify antibiotics in food in their Pioneer Fund project that started in June. The method is suitable for use with drinking water, milk and many other types of food, including meat juices, explains Project Coordinator Dr. Christiane Hübner: “The liquid sample simply needs to be mixed with a reagent solution. If antibiotics are present in the sample, the colour changes from red to blue.” This colour change can be photographed using a smartphone and the image is then evaluated by an app developed by Koeppl and his team.

The screening reagent consists of short RNA fragments, so-called aptamers, that are bound to gold nanoparticles. The aqueous solution containing these aptamer-gold nanoparticles is red. If antibiotics are present in the food, the aptamers detach from the gold particles and the now free gold particles appear blue. Süß and her team had already selected potentially suitable aptamers using a screening process. Koeppl and his team optimised their molecular structure using machine learning methods. The chemical synthesis was then completed in Süß's laboratory.

The researchers want to use the funding from the Pioneer Fund to clarify, amongst other things, how sensitive the antibiotics test is and whether it will be impaired by proteins or other components of the food. “Our aim is to develop a reliable and easy-to-use test for end consumers”, emphasises Hübner. There is a great deal of interest in this type of test because previous testing methods were time consuming and not suitable for use at home.