10 Cambridge spinouts forging a future for our planet

skbf2 — Fri, 25 Oct 2024 10:07:50 +0000

10 companies taking Cambridge ideas out of the lab and into the real world to address the climate emergency.

‘Vegan spider silk’ provides sustainable alternative to single-use plastics

sc604 — Thu, 10 Jun 2021 09:00:00 +0000

̽��ֱ��researchers, from the ̽��ֱ�� of Cambridge, created a polymer film by mimicking the properties of spider silk, one of the strongest materials in nature. ̽��ֱ��new material is as strong as many common plastics in use today and could replace plastic in many common household products.

̽��ֱ��material was created using a new approach for assembling plant proteins into materials that mimic silk on a molecular level. ̽��ֱ��energy-efficient method, which uses sustainable ingredients, results in a plastic-like free-standing film, which can be made at industrial scale. Non-fading ‘structural’ colour can be added to the polymer, and it can also be used to make water-resistant coatings.

̽��ֱ��material is home compostable, whereas other types of bioplastics require industrial composting facilities to degrade. In addition, the Cambridge-developed material requires no chemical modifications to its natural building blocks, so that it can safely degrade in most natural environments.

̽��ֱ��new product will be commercialised by Xampla, a ̽��ֱ�� of Cambridge spin-out company developing replacements for single-use plastic and microplastics. ̽��ֱ��company will introduce a range of single-use sachets and capsules later this year, which can replace the plastic used in everyday products like dishwasher tablets and laundry detergent capsules. ̽��ֱ��results are reported in the journal Nature Communications.

For many years, Professor Tuomas Knowles in Cambridge’s Yusuf Hamied Department of Chemistry has been researching the behaviour of proteins. Much of his research has been focused on what happens when proteins misfold or ‘misbehave’, and how this relates to health and human disease, primarily Alzheimer’s disease.

“We normally investigate how functional protein interactions allow us to stay healthy and how irregular interactions are implicated in Alzheimer’s disease,” said Knowles, who led the current research. “It was a surprise to find our research could also address a big problem in sustainability: that of plastic pollution.”

As part of their protein research, Knowles and his group became interested in why materials like spider silk are so strong when they have such weak molecular bonds. “We found that one of the key features that gives spider silk its strength is the hydrogen bonds are arranged regularly in space and at a very high density,” said Knowles.

Co-author Dr Marc Rodriguez Garcia, a postdoctoral researcher in Knowles’ group who is now Head of R&D at Xampla, began looking at how to replicate this regular self-assembly in other proteins. Proteins have a propensity for molecular self-organisation and self-assembly, and plant proteins, in particular, are abundant and can be sourced sustainably as by-products of the food industry.

“Very little is known about the self-assembly of plant proteins, and it’s exciting to know that by filling this knowledge gap we can find alternatives to single-use plastics,” said PhD candidate Ayaka Kamada, the paper’s first author.

̽��ֱ��researchers successfully replicated the structures found on spider silk by using soy protein isolate, a protein with a completely different composition. “Because all proteins are made of polypeptide chains, under the right conditions we can cause plant proteins to self-assemble just like spider silk,” said Knowles, who is also a Fellow of St John's College. “In a spider, the silk protein is dissolved in an aqueous solution, which then assembles into an immensely strong fibre through a spinning process which requires very little energy.”

“Other researchers have been working directly with silk materials as a plastic replacement, but they’re still an animal product,” said Rodriguez Garcia. “In a way, we’ve come up with ‘vegan spider silk’ – we’ve created the same material without the spider.”

Any replacement for plastic requires another polymer – the two in nature that exist in abundance are polysaccharides and polypeptides. Cellulose and nanocellulose are polysaccharides and have been used for a range of applications, but often require some form of cross-linking to form strong materials. Proteins self-assemble and can form strong materials like silk without any chemical modifications, but they are much harder to work with.

̽��ֱ��researchers used soy protein isolate (SPI) as their test plant protein, since it is readily available as a by-product of soybean oil production. Plant proteins such as SPI are poorly soluble in water, making it hard to control their self-assembly into ordered structures.

̽��ֱ��new technique uses an environmentally friendly mixture of acetic acid and water, combined with ultrasonication and high temperatures, to improve the solubility of the SPI. This method produces protein structures with enhanced inter-molecular interactions guided by the hydrogen bond formation. In a second step, the solvent is removed, which results in a water-insoluble film.

̽��ֱ��material has a performance equivalent to high-performance engineering plastics such as low-density polyethylene. Its strength lies in the regular arrangement of the polypeptide chains, meaning there is no need for chemical cross-linking, which is frequently used to improve the performance and resistance of biopolymer films. ̽��ֱ��most commonly used cross-linking agents are non-sustainable and can even be toxic, whereas no toxic elements are required for the Cambridge-developed technique.

“This is the culmination of something we’ve been working on for over ten years, which is understanding how nature generates materials from proteins,” said Knowles. “We didn’t set out to solve a sustainability challenge -- we were motivated by curiosity as to how to create strong materials from weak interactions.”

“ ̽��ֱ��key breakthrough here is being able to control self-assembly, so we can now create high-performance materials,” said Rodriguez Garcia. “It’s exciting to be part of this journey. There is a huge, huge issue of plastic pollution in the world, and we are in the fortunate position to be able to do something about it.”

Xampla's technology has been patented by Cambridge Enterprise, the ̽��ֱ��'s commercialisation arm. Cambridge Enterprise and Amadeus Capital Partners co-led a £2 million seed funding round for Xampla, joined by Sky Ocean Ventures and the ̽��ֱ�� of Cambridge Enterprise Fund VI, which is managed by Parkwalk.

Reference:
A. Kamada et al. ‘Self-assembly of plant proteins into high-performance multifunctional nanostructured films.’ Nature Communications (2021). DOI: 10.1038/s41467-021-23813-6

Researchers have created a plant-based, sustainable, scalable material that could replace single-use plastics in many consumer products.

It was a surprise to find our research could also address a big problem in sustainability: that of plastic pollution

Tuomas Knowles

Xampla

Packaging incorporating Xampla's plant-based plastic

̽��ֱ��text in this work is licensed under a Creative Commons Attribution 4.0 International License. Images, including our videos, are Copyright © ̽��ֱ�� of Cambridge and licensors/contributors as identified. All rights reserved. We make our image and video content available in a number of ways – as here, on our main website under its Terms and conditions, and on a range of channels including social media that permit your use and sharing of our content under their respective Terms.

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̽��ֱ�� of Cambridge - Marc Rodriguez Garcia

10 Cambridge spinouts forging a future for our planet

‘Vegan spider silk’ provides sustainable alternative to single-use plastics