Scientists find way to spin artificial silk out of cow whey protein

Scientists have discovered a new way of spinning out artificial silk from the whey proteins of the cow. This finding may lead to a new generation of novel biosensors or self-dissolving wound dressings.

Silk is one such material that has many remarkable characteristics and it remains highly in demand in many areas across the world.
Though lightweight, silk is stronger than some metals and can be extremely elastic. Farmed silkworms currently harvest silk, which is quite costly.

“Across the globe, many research teams are working on methods to artificially produce silk,” said Stephan Roth from DESY.

“Such artificial materials can also be modified to have new, tailor-made characteristics and can serve for applications like novel biosensors or self-dissolving wound dressings, for example,” said Roth, an adjunct professor at Royal Institute of Technology (KTH) in Sweden.

However, in the case of silk, imitating the nature proved hard. The focus of the researchers was self-assembling materials.

“Some proteins assemble themselves into nanofibrils under the right conditions. A carrier fluid with these protein nanofibrils is then pumped through a small canal,” said Fredrik Lundell from KTH.

“Additional water enters perpendicular from the sides and squeezes the fibrils together until they stick together and form a fibre,” said Lundell.

The latter process is called hydrodynamic focussing and the team has used it before for producing artificial wood fibres from cellulose fibrils.
“In fact, the process has several similarities with the way spiders produce their silk threads,” said Christofer Lendel, also from KTH.

In the new study, a protein from cow’s whey formed the nanofibrils under the influence of heat and acid.

The fibrils shape and characteristics strongly depend on the protein concentration in the solution. At less than four per cent, long, straight and thick fibrils form.

They can be up to 2,000 nanometres long and four to seven nanometres thick.

However, at an only slightly higher protein concentration of six per cent or more in the initial solution, the fibrils remain much shorter and thinner with an average length of just 40 nanometres and a thickness of two to three nanometres.

Also, they are curved looking like tiny worms and 15 to 25 times softer than the long, straight fibrils.

In the lab, however, the short and curved fibrils formed much better fibres than the long and straight fibrils. Researchers obtained artificial silk fibres that were roughly five millimetres long and of medium quality.

“We used the whey protein to understand the underlying principle in detail. The whole process can now be optimised to obtain fibres with better or new, tailor-made properties,” said Lendel.

This way, the results of the study could help to develop materials with novel features, for example artificial tissue for medical applications. The study was published in the journal PNAS.

(With inputs from PTI)