Antimicrobial fibre made from crab shells and seaweed

Researchers from Aalto University, the University of São Paulo and the University of British Columbia have created a new kind of fibre from a combination of chitin nanoparticles — extracted from residual blue crab shells — and alginate, a compound found in seaweed. The new bio-based material is sturdy and has antimicrobial properties, according to a study published in ACS Sustainable Chemistry & Engineering.

Professor Orlando Rojas, from the Biobased Colloids and Materials (BiCMat) team at Aalto University, said the researchers 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,” Prof Rojas 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. Brown algae has 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 using simple procedures.

The team studied how differences in the concentration of each component, the size of the nanoparticles and other variables affect the mechanical properties and spinability of the final thread. With this information, they were able to produce strong, flexible threads continuously.

The research team sees great potential for the material to be 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,” Prof Rojas noted. He said that for further development, the team is looking into scalability after demonstrating that the threads can be formed continuously.

“This can be eventually made scalable by using simultaneous microfiber dry-drawing from the respective suspensions,” he said.

Image caption: When the chitin (pink) and the alginate (light blue) are brought into contact, the alginate begins to wrap around the chitin particles and forms filaments that are aligned when pulled up. Image credit: Rafael Grande.

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