Abstract:
Despite much research, there are very few commercial prolamin bio-plastics. The major
reason, apart from their high cost, is that they have inferior functional properties compared to
synthetic polymer plastics. This is because the prolamins are complex, each consisting of
several classes and sub-classes and the functional properties of their bio-plastics are greatly
affected by water. Prolamin bio-plastics are produced by protein aggregation from a solvent
or by thermoplastic processing. Recent research indicates that protein aggregation occurs by
polypeptide self-assembly into nanostructures. Protein secondary structure in terms of α-
helical and β-sheet structure seems to play a key, but incompletely understood role in
assembly. Also, there is inadequate knowledge as to how these nanostructures further
assemble and organize into the various forms of prolamin bio-plastics such as films, fibres,
microparticles and scaffolds. Some improvements in bio-plastic functionality have been
made by better prolamin solvation, plasticization, physical and chemical cross-linking,
derivatization and blending with other polymers. The most promising area of commercialization is the biomedical field where the relative hydrophilicity, compatibility and
biodegradability of particularly zein and kafirin are advantageous. With regard to biomedical
applications, “supramolecular design” of prolamin bio-plastics through control over interand
intramolecular weak interactions and SS/SH interchange between and within
polypeptides appears to have considerable potential.
