Plastics are essential to modern living, they preserve our food, encase our electronics and are even in our toothpaste! However, most modern plastics are non-biodegradable, harmful to other animals and contribute to landfill. If we are to halt plastic pollution, we need sustainable alternatives, and quick!
But do not fear, protein based materials such as silks and have great potential to take the place of traditional plastics made from polymers. Proteins are fully biodegradable biopolymers with tuneable functionality and therefore many exciting applications.
Take spider silk, the strongest material known to man. Spider silk is so strong because it has the capability to self-assemble into large structures made solely of protein molecules, called ‘macrostructures’. This happens because the protein chains can take advantage of the many hydrogen atoms and aromatic rings they contain to form a very high density of intermolecular bonds (such as hydrogen bonds). Although each intermolecular bond is weak, there are millions of these in each protein chains, meaning that the silk materials formed are extremely strong. Other proteins also share this ability to self-assemble into very strong macrostructures, which have the potential to replace other non-biodegradable polymers.
We can manipulate protein liquids into droplets using microfluidic techniques. Microfluidics confine liquids into tiny channels which then allows for the manipulation of their behaviour. By mixing different liquids which do not dissolve in one another, we can form microscale droplets. These droplets can be used to add functionality to make new materials, or to add functionality to support materials, such as silk or glass.
My research focusses on using these microfluidic techniques to make useful films from fully biodegradable short chain proteins called peptides. For example, I am working on making colourful films from peptide spheres, called colloids, made through these microfluidic techniques. Having precise control of the size and distribution of droplets allows us to tune arrays of particles such that they can produce a spectrum of different colours. These films produce colour based on the interaction of light waves with arrays of particles, rather than using potentially harmful dyes.
However, there are many other exciting things that can be done with protein materials. I will also be looking at making antimicrobial protein films by incorporating biocompatible metallic nanoparticles such as selenium into self-assembled protein films. These films could then be used to reduce the risk of wound infection without being harmful to the patient.
There is a vast amount of work going into protein self-assembly and the creation of new exciting materials from these versatile, naturally sourced biopolymers. However, it is important that research continues if we are to realise the potential of these materials.
NanoDTC PhD Student, c2021