May 31, 2023

Investigating sustainable silk and collagen with bacterial help

Take a morning walk through the garden and you might spy a spider’s web, its gossamer appearance disguising the fibres’ strength, which can outcompete steel of the same weight. Conveniently reproducing this property in similar fibres is desirable, but synthetic and animal-derived alternatives are not sustainable, ethical, or economical. New research led by Sesilja Aranko and funded by the Novo Nordisk Foundation Research Leader Programme aims to change this outlook.

Biomaterials come in all shapes and sizes, with spider silk fibres being just one example of a natural material with desirable properties. Our bones, cartilage, and skin – all of which are formed of another key building block, collagen – also possess beneficial characteristics, whether that’s strength, flexibility, or elasticity. But regardless of their shape and texture, these biomaterials have one thing in common: they are made of proteins, strings of repetitive molecules folded into precise shapes.

Many, if not all of these naturally occurring proteins are altered through a process called post-translational modification. This is where small chemical tweaks are made to the proteins after they have been synthesised by the cell.

“We know these modifications are important, but for many of them we don’t know exactly what their purpose is,” explains Sesilja Aranko. “We do know that they can have an impact on the mechanical properties of biomaterials though.”

From molecules to fibres
Sesilja Aranko’s innovative research spans scales. At the molecular level she will investigate the protein structures and post-translational modifications that make up biomaterials such as silks. In tandem, she will perform experiments to gain a better understanding of the biomaterials’ mechanical properties.

“During my PhD I studied molecular and structural biology at the fundamental level. But after I moved to Aalto University I learnt more about biomaterials and it was really exciting,” she explains. “Combining these two fields has been essential for me.”

To bridge these perspectives, she uses bacteria to economically, ethically and sustainably produce proteins, both with and without the post-translational modifications.

“One big challenge of the project is to produce these proteins in a controlled manner and identify which modifications the proteins have,” says Sesilja Aranko. “Once the bacteria have produced the proteins – silk or collagen for example – we can use our spinning set-up to produce biomaterials, such as fibres.”

Fibres such as those produced by spiders are a first step, but she is keen to investigate naturally produced films and adhesives too.

Her approach means that she can then begin to understand what effects the post-translational modifications have on the biomaterials’ mechanical properties, compared to the same protein that has not been modified.

“These modifications could even give additional functionalities to the material, such as the ability to self-heal,” she continues.

Sesilja Aranko will also try to better understand the natural materials and their assembly at both the molecular and mechanical level.

“It is difficult for humans to make these materials in the same way that nature does,” she explains. “But if we can better understand the unique properties of the natural material at a molecular level, we can innovate to make them in our own way.”

Having such a fundamental understanding of the materials means that one day it might even be possible to improve on nature’s materials without using harmful chemicals or animal-derived products.

Far-reaching impacts
Although far in the future, there are potential real-world applications for post-translationally modified biomaterials produced by bacteria. Silk produced by silkworms is already used as one option to stitch together wounds thanks to its handleability and low risk of an allergic reaction in the patient. But a post-translationally modified version made by bacteria could offer further benefits. Firstly, by avoiding the use of animals in its production, and possibly also by tweaking its molecular structure to incorporate improved mechanical properties.

Alongside high-tech applications, other biomaterials could even replace commonplace items such as food wrapping.

“There’s a lot of potential for biomaterials to help reduce the amount of food waste and in doing so replace current plastic wrappings that are not sustainable,” says Sesilja Aranko.

There is also a big need for environmentally friendly glues, and protein-based adhesives are one of the potential solutions.

“This funding is so important as it allows us to tackle very challenging scientific problems and hopefully address some societal issues too,” she says.

For her professional career the Novo Nordisk Research Leader Programme grant also has a huge impact: “This grant allows me to establish my own group and research profile, both of which wouldn’t be possible without this kind of funding. It will take us a while to tackle all of our questions, but this is something that the Research Leader Programme funding will enable.”

DKK 361 million awarded
The Foundation’s Research Leader Programme funds daring and innovative project ideas that may lead to significant scientific breakthroughs. The five-year grants are awarded to talented researchers at different stages of their careers.

A total of DKK 361 million has been awarded to 37 researchers in the 2023 round. Sesilja Aranko is one of 16 Emerging Investigators to receive an award, granted to promising researchers who want to establish or are in the process of establishing their own research group and research leader profile.

In total, the Foundation has now awarded more than DKK 2 billion to more than 200 researchers through the Programme since it was established in 2018.

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Further information
Christian Mostrup, Head of Press, Novo Nordisk Foundation,, +45 3067 4805