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Cute 'lil' crab sitting on the beach

Crab-shell and seaweed compounds spin into yarns for sustainable materials

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Researchers have found a way to make bio-based fibres from a combination of chitin nanoparticles extracted from residual blue crab shells and alginate, a compound found in seaweed.

Bio-based fibres are made from two renewable marine resources and show promise in advanced applications, in wovens and medical materials, among others. The threads draw strength from the crab chitin component and flexibility from seaweed alginate.

The group of researchers – a team from Aalto University in Finland, the University of São Paulo, Brazil, and the University of British Columbia in Canada – said the new bio-based material is sturdy and has antimicrobial properties.

As part of their research, the team investigated how differences in the concentration of each component, the size of the nanoparticles, and other variables affect the mechanical properties and spinnability of the final thread. And with this information, they were able to produce strong, flexible threads continuously.

Professor Orlando Rojas from the Biobased Colloids and Materials (BiCMat) team at Aalto University said they wanted to make a fibre that combined the properties of chitin – known for its antimicrobial properties – and seaweed alginate, which forms strong gels.

“The designed material took advantage of the strong interaction between the components, which are oppositely charged,” he said. “We found that when a solution of alginate contacts a suspension of chitin nanofibres, the alginate wraps around the chitin nanoparticles, forming fibrils that align in parallel as the thread is drawn upward.”

Alginate dissolves readily in water – while brown algae have alginic acid in its cell walls, which can be converted to sodium alginate. The blue crab shells were ground and purified; then the material was partially deacetylated – the removal of an acetyl group from a chemical compound – using simple procedures.

The research team stated that they see great potential for the material being used for such things as threads for surgical procedures and webs for internal tissue engineering. Other uses include pads and web-like meshes for applications on the skin, for wound healing, skin conditioning and burn treatments.

“It’s a well-known fact that that chitin nanoparticles are antimicrobial and bioactive; for example, they have shown to help hair growth,” Rojas said.

Rojas added that for further development, the research team is looking into scalability after demonstrating that the threads can be formed continuously. “This can be eventually made scalable by using simultaneous microfibre dry-drawing from the respective suspension,” Rojas concluded.

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