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Doctoral defence of M.Sc. Teemu Välisalmi



Teemu Välisalmi defended his doctoral dissertation on the 1st of March 2024. The title of the thesis is Exploring Silk Protein Assembly Mechanisms for high-performance Materials.


His opponent Professor Yael Politi came from Dresden University of Technology, Germany. Teemu performed his doctoral research under the supervision of Professor Markus Linder, at the Department of Bioproducts and Biosystems of Aalto University.


Materials from silk proteins

Due to the unique structure of silk proteins, they possess various beneficial properties such as high tensile strength, flexibility, and biodegradability. The most promising silk proteins are found in spiders. Although acquiring these proteins directly from nature is challenging, the application of genetic engineering allows to produce large quantities of "recombinant" silk proteins. However, the challenge remains in determining the additional processes needed to manufacture durable silk-based materials from the produced recombinant silk. Previous studies indicate that solutions lie in the complex spinning mechanism of silk-producing animals.The doctoral thesis initially focused on the spinning mechanism of silkworm silk. The protein content in the gland was mapped by measuring the variation of amino acids, correlating with the silk mass's ability to form fibers. This ability was further enhanced by a simple adjustment of acidity. Subsequently, the research addressed the production of fibers from recombinant silk and regenerated silk. The separation of recombinant silk into different phases was identified as a crucial intermediate step for achieving high tensile strength in fibers. Finally, the study moved beyond fibers to discuss a method for producing water resistant, or hydrophobic, silk films. This hydrophobicity developed as the silk protein structures orderly arranged on the surface of the film. The arrangement occurred only under specific conditions, with high relative humidity and the right salt concentration identified as critical parameters. However, the films remained brittle, and further investigation is needed to enhance their durability.


More information and the electronic thesis can be found at: https://aaltodoc.aalto.fi/items/de6bf1d0-8c09-464b-9ea4-66ca7237d744


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