Mixed Multilayers of Protein Fibrils with Sodium or Calcium Alginates

A layer-by-layer approach is used for the preparation of multilayer films on the basis of biomacromolecules and their aggregates, protein fibrils. In this work, the fibrils were prepared from β-lactoglobulin and oat globulin, while sodium and calcium alginates were used as oppositely charged polyelectrolytes. Mixed layers of fibrils with alginate salts were formed at the air/liquid interface by the sequential replacement of solutions in the sublayer. The use of alginate salts resulted in a high stiffness of the mixed layers, allowing their transfer to a solid substrate without disturbing their uniformity. Each mixed layer had a thickness between 50 and 80 nm on a solid substrate. This gave the possibility to modulate the properties of the mixed film by changing its thickness and composition with the aim of providing optimal mechanical properties of the composite film.