A team of engineers at Penn State, University Park, PA, is using squid to create an eco-friendly thermoplastic that can be used in 3D printing. Most plastics are made from fossil fuel sources or from synthetic oils. Thermoplastics can melt, be formed, and then solidify without degrading materials properties. The squid thermoplastic can be fabricated either as a thermoplastic, heated and extruded or molded, or be dissolved in a simple solvent and used in film casting. The researchers say that it can also be used in 3D printers to create complicated geometric structures.
Melik C. Demirel, professor of engineering science and mechanics, who led the research, said that his team examined the protein complex that exists in the squid ring teeth (SRT). The researchers looked at the genetic sequence for the protein complex molecule and tried synthesizing a variety of proteins from the complex. Some were not thermoplastic, but others showed stable thermal response. For example, the smallest known molecular weight SRT protein was a thermoplastic.
To manufacture this small, synthetic SRT molecule, the researchers used recombinant techniques. They inserted SRT protein genes into E. coli, so that the bacteria could produce the plastic molecules as part of their normal activity and the thermoplastic was then removed from the media where the E. coli lived.
The thermoplastic the researchers created is semi-crystalline and can be rigid or soft. It has a very high tensile strength and is a wet adhesive; it will stick to things even if it is wet. It has a variety of tunable properties, which can be adjusted to individual requirements of manufacturing.