Combining wood fibers and spider silk for new materials

Posted Sep 22, 2019 by Tim Sandle
A combination of wood fibers and spider silk could create a new type of material that can rival plastic in terms of versatility but without the negative impact upon the environment, new research shows.
British garden spider  spinning a web across a lawn.
British garden spider, spinning a web across a lawn.
Trials on the new material, conducted at Aalto University, show how the material can outperform most synthetic and natural materials, in terms of strength and stiffness, plus an increased toughness.
The properties of an 'ideal material' are both strength and extensibility. However, having both of these properties present at the same time has provided a great challenge to materials scientists. This is because increasing strength tends to result in a loss of extensibility and vice versa. However, drawing inspiration from nature, Finnish researchers appear to have succeeded in overcoming this challenge.
The achievement is with a new bio-based material, formed by gluing together wood cellulose fibers and the silk protein which makes up spider web threads. The silk was not produced by spiders but instead it was made synthetically using genetically modified bacteria. The resultant material is a very firm and resilient. In addition, the new material is also fully biodegradable.
According to lead scientist Professor Markus Linder: "We used birch tree pulp, broke it down to cellulose nanofibrils and aligned them into a stiff scaffold. At the same time, we infiltrated the cellulosic network with a soft and energy dissipating spider silk adhesive matrix."
In terms of future applications, the material could become a replacement for plastic, as well as being used in bio-based composites and for medical applications, such as surgical fibres. Other uses include textiles and in packaging.
A description of the new material and the associated protein engineering is presented in the journal Science Advances, with the research paper headed "Biomimetic composites with enhanced toughening using silk-inspired triblock proteins and aligned nanocellulose reinforcements."