The protein of egg white, albumen, can be polymerized to make a synthetic biopolymer that might have a role to play in a sustainable future in health and "green" technologies, according to researchers from the USA and India. Pulickel Ajayan of Rice University and colleagues explain that their novel bio-material has "excellent stiffness and ductility" due to its polymerization with primary amine-based chemical compounds which form strong covalent bonds.
Nature provides inspiration in many ways for materials scientists. Often, efforts are focused on attempting to emulate a biological material with entirely synthetic versions. Conversely, taking a natural material and attempting to modify it for a particular application also proves very useful. One additional perspective in building on millions of years of evolution is that materials derived from living things can open up a more environmentally benign route to chemical production in that limited resources, such as crude oil, are precluded from the ingredients and so a sustainable, close-cycle, approach with zero waste might be adopted.
Of particular interest are porous, stiff, and biocompatible materials derived from nature. There have been many experimental composites investigated that are based on carbon, collagen, and ceramic materials. Today, implantable devices add another dimension to the search for biocompatible materials. Tissue scaffolds, drug release systems, and prosthetics need to be non-toxic, biocompatible, and to last only long enough to do their job before being harmlessly absorbed by the body and the waste products excreted. One of the more well-known and accessible biological materials that might provide a starting point is the protein of egg white - albumen.
The team has now cross-linked egg albumen with primary amine-based molecules, including diethylenetriamine (DETA) to build a novel bio-polymer. Simple physical mixing and sunlight are all that is needed to make the material, which can then be cured in an oven. Standard macroscopic tensile and compression tests show the physical strengths and weaknesses of the material, the team reports. And, in situ local indentation and atomic form microscopy (AFM) modulus mapping confirms the physical characteristics of the new material and the results are corroborated by molecular dynamics (MD) simulations.
Intriguingly, this synthetic "meringue" is not only stiff like a culinary meringue, it is also entirely edible and biocompatible. At the technological level, however, the team has tested its biological cell viability and cell growth successfully. The use of the material has a circuit board based for implantable electronics has also been demonstrated. [Ajayan, P.M. et al., Mater Today Chem (2018) 9, 73-79; DOI: 10.1016/j.mtchem.2018.04.001]
David Bradley blogs at Sciencebase Science Blog and tweets @sciencebase. His popular science book Deceived Wisdom is now available.