Spider silk is a bioactive material with a wide range of medical uses. Researchers at KTH in Stockholm have synthesized artificial spider silk and combined it with nanocellulose to produce hybrid silk fibers. We interviewed researcher My Hedhammar from KTH.

What process did you use to create the artificial spider silk?

Our artificial spider silk is produced using recombinant DNA technology and a lab bacteria.

What are the advantages of this process compared to the alternatives?

This process is simple, cheap and allows control and scalability.

Does the artificial spider silk have the same properties as natural spider silk?

Our artificial silk contains one miniaturized spider silk protein, which makes it more defined and reproducible than natural spider silk. The initial mechanical properties are essentially the same, with high elasticity and strength. However, the artificial silk is not as extendible as natural silk. Since the artificial silk is made from a defined protein solution, it is possible to process it into a wide variety formats e.g. fibers, films, nets and foam. The recombinant technology also allows functionalization of the artificial silk with bioactive domains such as enzymes, growth factors, affinity modules etc.

Can you tell us something about the properties of the cellulose nano fibrils?

Cellulose nano fibrils can be obtained from trees and are thus renewable and available in large volumes. Moreover, they are biodegradable, virtually non-toxic and offer outstanding mechanical properties.

Which technology was used to combine the spider silk and the cellulose nano fibrils?

We utilized a new method for constructing fibers from nano fibrils, based on flow focusing. Since there are favourable interactions between silk and cellulose, it is possible to include a fraction of silk fusion proteins in the process to obtain composite materials.

What are the main properties of the composite?

The silk-nanocellulose composition gives ultrastrong fibers which have specific bioactivities (from the silk fusions) and are also biodegradable.

Can the properties of the composite be tuned by using a different ratio of silk and cellulose?

By the addition of different silk fusions it is possible to obtain a variety of functional materials with specific bioactivities.

What do you consider to be the possible applications of the composite within healthcare?

For example these composites could be used to develop wound dressings with healing and/or antimicrobial properties, or engineering of load bearing tissue.

Do you also see applications outside healthcare?

Depending on the functionality chosen in the silk fusion, it could be used for e.g. biocatalysts, biosensors or affinity matrices.

Are you licensing the technology for commercial use?

The technology is patented by Spiber Technology AB.

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