One of the great challenges of materials engineering has been to create a product that is strong and extensible at the same time.
Until now, increasing the rigidity of a material meant reducing its extensibility, and vice versa.
However, researchers in Finland have solved the problem by drawing inspiration from nature and biological ingredients to create a truly revolutionary product.
t is a unique combination of materials that exceeds firmness, resistance and extensibility to current synthetic and natural products and that, in addition, is biodegradable.
Wood and cobweb
Technicians and engineers from the Aalto University and the VTT Technical Research Center in Finland, adhered wood cellulose fibers to the cobweb silk protein.
Cobweb silk is one of the most flexible and resistant natural products.
The result is a very firm, elastic and resistant material that could well replace plastic in multiple uses.
Its future applications include biologically based compounds, medical products, surgical fibers, the textile industry, packaging and wrapping.
According to Professor Markus Linder, from Aalto University, nature offers excellent raw materials that are readily available for the development of new materials, such as rigid cellulose and the resistant and flexible silk that were used in the research.
The advantage of both materials is that, contrary to plastic, they are biodegradable and do not harm the environment or constitute a potential health risk such as microplastics.
"Our researchers only need to be able to reproduce these natural properties," said Professor Linder, who also led the research.
materials and methods
One of the natural products they used came from birch, an abundant tree in the forests of northern Europe, which they combined with synthetically cloned silk protein.
The birch (abedul) is an abundant tree in northern Europe.
Wood pulp and silk are biopolymers that demonstrate great potential as future sustainable materials.
They also have properties that complement each other and are suitable for combining in composite materials where cellulose forms the stiffening element and silk the resistant matrix.
"We use birch pulp, disintegrated to obtain nano fibrils and we align them in the form of a firm scaffold. At the same time, we infiltrate that structure with an adhesive web of cobweb silk that is soft and dissipates energy," explained Pezhman Mohammadi, scientist VTT researcher.
Silk is a natural product that is secreted by animals like silkworms and that is also found in cobwebs.
The secret of the web's resistance
However, the silk used by researchers at the University of Aalto was not actually taken from the secretions of these invertebrates but produced by scientists combining bacteria and synthetic DNA.
"As we know the structure of DNA, we can copy it and use it to make silk protein molecules that are chemically similar to those found in the threads of a web," Linder said. "The DNA contains all this information."
The researchers measured the resistance of various combinations of the material.
The researchers added that their work illustrates the new and versatile possibilities of protein engineering.
"In the future, we could manufacture similar compounds with slightly different basic materials and achieve a collection of products with different characteristics for other applications," Pezhman Mohammadi said.
"Currently, we are working on the production of new composite materials such as implants, impact resistant objects and other products," the scientist concluded.
The research project is part of a work developed by the Center for Excellence in Molecular Engineering of Biosynthetic Hybrid Materials (Hyber). (I)