Plasticizing Effects of Polyamines in Protein-Based Films

Area of Science:

• Materials Science
• Biochemistry

Background:

• Protein-based films offer sustainable alternatives to synthetic plastics.
• Controlling film properties like handleability and flexibility is crucial for applications.

Purpose of the Study:

• To investigate the effect of polyamines (spermidine, spermine) and glycerol on the properties of bitter vetch protein films.
• To understand the role of polyamines in modifying protein nanoparticle size and zeta potential.

Main Methods:

• Zeta potential and nanoparticle size measurements of film-forming solutions.
• Analysis of native and heat-denatured bitter vetch proteins.
• Varying pH, polyamine concentrations, and glycerol presence.

Main Results:

• Polyamines decreased negative zeta potential and increased nanoparticle size due to ionic interactions and aggregation.
• Handleable films from native proteins required glycerol (≥33 mM) or spermidine (≥4 mM).
• Spermidine (2 mM) enabled handleable films from heat-denatured proteins, acting as an ionic plasticizer, unlike spermine.

Conclusions:

• Spermidine is effective as an ionic plasticizer for bitter vetch protein films, particularly for heat-denatured proteins.
• Both polyamines can act as glycerol-like plasticizers at higher concentrations.
• Aliphatic polycations present a promising avenue for developing novel protein-based films.