Life in Plastic: It’s Fantastic

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Sustainable and efficient thermoplastic production may be possible thanks to…squid?

It may be that squid are more than just catching and eating.

Melik Demirel’s laboratory in Pennsylvania State University identified proteins that may aid in sustainable, efficient production of thermoplastic, a (typical) polymer material that is malleable (shapeable) under various temperatures. Thermoplastic can also be used as ink for 3D printing, a goal that the Demirel lab would like to achieve.

Image via Sue Hickton.

Squid teeth are located within the animal’s suction cup, and are used to hook underwater prey. Image via Sue Hickton.

Demirel et al. (2014) extracted these proteins of interest from the suction cups—or squid ring teeth (SRT)—of a common European squid species, Logilo vulgaris. The traits of these proteins were identified using a series of experiments and DNA sequencing technologies (known as next generation sequencing).

Using differential scanning calorimetry, the glass transition temperature of the SRT proteins were determined to be 32oC. The glass transition temperature represents a (mid) range of temperatures whereby the material (in this case, SRT) converts from a hard, rigid structure to a ‘rubbery’ one. The lab also found that the proteins exhibit variable mechanical properties during wet or dry conditions.

These properties allow the SRT proteins to produce ring teeth that are thermoplastic. The SRT can be shaped into various 3D geometries (i.e. curved ribbons, colloids) and may also be molded into nanotubes or fibres using different processing techniques (i.e. fibre extrustion) and reactions with various chemicals (i.e. poly-ethylene-oxide).

Additionally, the Demirel lab attempted to identify the genes that constitute the SRT, in hopes of identifying (and isolating) specific genes that play a major role for SRT (and thermoplastic) production. The aspect of this experiment is important, so in the future we can recombinantly express SRT proteins. By recombinantly expressing SRT proteins, we can ultimately synthesize thermoplastics in a sustainable manner without having to directly extract the proteins from squid, which may be costly and raise ethical concerns of some sorts.

Demirel states:

Direct extraction or recombinant expression of protein based thermoplastics opens up new avenues for materials fabrication and synthesis, which will eventually be competitive with the high-end synthetic oil based plastics…

Furthermore, Demirel et al. (2014) are hopeful that thermoplastic/SRT production via recombinant expression of SRT proteins will serve uses related to drug delivery systems, biomaterial coatings, and membrane filtration.

 Renee C. has received her B.Sc. in Honours Life Sciences at McMaster University. She loves educating others about different topics in science, and has developed a passion for scientific outreach. When she’s not writing articles for Hemtecks, she’s either volunteering or checking her social media accounts every 20 minutes. Along with Tiffany (Tianhemtecks), she also facilitates the blog’s Facebook page. 


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